Difference between revisions of "Modding Tutorials/PatchOperations"

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{{DISPLAYTITLE:PatchOperations}}
 
{{BackToTutorials}}
 
{{BackToTutorials}}
−
{{stub}}
 
  
−
RimWorld Alpha 17 added a new modding feature: '''XML PatchOperations'''. Using these allows mods to edit specific elements of XML defs, rather than simply overwriting the old def with a new one, which was the required approach until A17. This greatly reduces mod conflicts, because mods that make separate changes to the same def won't necessarily overwrite one another's changes. Mods using PatchOperations can avoid requiring special compatibility mods, and can even add special features conditional on other mods being loaded.
+
PatchOperations are a feature that allows you to modify the content of XML Defs. Prior to RimWorld alpha 17, modders could only modify Defs by creating new ones that overwrote the original; this often resulted in compatibility issues as if more than one mod tried to overwrite the same Def, only the last mod in the load order would succeed as prior ones would themselves be overwritten.
  
−
Here's a simple example of replacing the texture path for deep water:
+
<div class="TableOfContentsContainer">
 +
<div class="TableOfContentsContainer-toc">
 +
__TOC__
 +
</div>
 +
<div class="TableOfContentsContainer-content">
 +
= Basics =
 +
 
 +
PatchOperations are written as XML nodes that go into your mod's <tt>Patches</tt> folder:
 +
 
 +
<source>
 +
MyModFolder
 +
├ About
 +
├ Defs
 +
└ Patches
 +
  └ MyPatchFile.xml
 +
</source>
 +
 
 +
Just as with XML Defs, folder and file names do not matter and you can freely name and organize your patch files in whatever manner you wish. Individual patches themselves are a standard XML file with <tt><Patch></tt> as the root tag:
 +
 
 +
<source lang="xml">
 +
<?xml version="1.0" encoding="utf-8"?>
 +
<Patch>
 +
 
 +
  <!-- PatchOperations go here -->
 +
 
 +
</Patch>
 +
</source>
 +
 
 +
== XPath ==
 +
Most PatchOperations must be targeted at one or more XML nodes inside the master XML document. This is done via [https://developer.mozilla.org/en-US/docs/Web/XPath XML Path Language] or XPath.
 +
 
 +
Note that an XPath is targeting the structure of the XML document after it's been parsed by RimWorld's parser, thus it has nothing to do with the actual file or folder paths. For example, if you wanted to add a stat value to the vanilla Wall building, you might use an XPath like so:
 +
 
 +
<code>Defs/ThingDef[defName="Wall"]/statBases</code>
 +
 
 +
* The first segment of any XPath targeting an XML Def will be <code>Defs/</code> as all XML Defs use the <code><Defs></code> root tag.
 +
* The square brackets denote a predicate, or conditional match. In this case, we are looking for <code>ThingDef</code>s that have a child tag <code>defName</code> equal to "Wall".
 +
 
 +
=== Targeting Attributes ===
 +
 
 +
You can target Defs that do not have a <code>defName</code> (such as abstract bases) by targeting their identifying attributes. For example, if you wanted to add another Stuff category to the abstract base Def for all shelves, you might use the following xpath:
 +
 
 +
<code>Defs/ThingDef[@Name="ShelfBase"]/stuffCategories</code>
 +
 
 +
You can use the same technique to target all Defs that inherit from a common base. For example, you could use the following xpath to target all <code>ThingDef</code>s that inherit from <code>ApparelBase</code>:
 +
 
 +
<code>Defs/ThingDef[@ParentName="ApparelBase"]</code>
 +
 
 +
=== Additional XPath Resources ===
 +
 
 +
* [https://developer.mozilla.org/en-US/docs/Web/XPath Mozilla Developer Network]
 +
* [https://www.w3schools.com/xml/xml_xpath.asp W3Schools XPath Tutorial]
 +
* [https://stackoverflow.com/questions/tagged/xpath StackOverflow XPath Tag]
 +
* Ludeon Forum Thread: {{LudeonThread|32785}}
 +
</div>
 +
</div>
 +
 
 +
= PatchOperation Types =
 +
 
 +
<div class="TwoColumnCollapsibleLayout">
 +
<div class="TwoColumnCollapsibleLayout-section">
 +
<div class="TwoColumnCollapsibleLayout-subtitle">Basic XML node operations:</div>
 +
<div class="TwoColumnCollapsibleLayout-text">
 +
* '''[[#PatchOperationAdd|PatchOperationAdd]]''' adds a provided child node to the selected node
 +
* '''[[#PatchOperationInsert|PatchOperationInsert]]''' inserts a provided sibling node above the selected node
 +
* '''[[#PatchOperationRemove|PatchOperationRemove]]''' deletes the selected node
 +
* '''[[#PatchOperationReplace|PatchOperationReplace]]''' replaces the selected node with the provided node
 +
</div>
 +
</div>
 +
<div class="TwoColumnCollapsibleLayout-section">
 +
<div class="TwoColumnCollapsibleLayout-subtitle">XML attribute operations:</div>
 +
<div class="TwoColumnCollapsibleLayout-text">
 +
* '''[[#PatchOperationAttributeAdd|PatchOperationAttributeAdd]]''' adds a provided attribute to the selected node if and only if the attribute name is not already present
 +
* '''[[#PatchOperationAttributeSet|PatchOperationAttributeSet]]''' sets a provided attribute for the selected node, overwriting the attribute value if the attribute name is already present
 +
* '''[[#PatchOperationAttributeRemove|PatchOperationAttributeRemove]]''' removes an attribute for the selected node
 +
</div>
 +
</div>
 +
<div class="TwoColumnCollapsibleLayout-section">
 +
<div class="TwoColumnCollapsibleLayout-subtitle">Special operations:</div>
 +
<div class="TwoColumnCollapsibleLayout-text">
 +
* '''[[#PatchOperationSequence|PatchOperationSequence]]''' contains a set of other PatchOperations, and aborts upon any operation failing
 +
* '''[[#PatchOperationAddModExtension|PatchOperationAddModExtension]]''' adds a ModExtension.
 +
* '''[[#PatchOperationSetName|PatchOperationSetName]]''' changes the name of a node.
 +
</div>
 +
</div>
 +
<div class="TwoColumnCollapsibleLayout-section">
 +
<div class="TwoColumnCollapsibleLayout-subtitle">Conditional operations:</div>
 +
<div class="TwoColumnCollapsibleLayout-text">
 +
* '''[[#PatchOperationFindMod|PatchOperationFindMod]]''' tests for the presence of another mod, and can do different operations depending on the result.
 +
* '''[[#PatchOperationConditional|PatchOperationConditional]]''' tests nodes, and can do different operations depending on the result.
 +
* '''[[#PatchOperationTest|PatchOperationTest]]''' tests nodes, which is useful inside a PatchOperationSequence
 +
</div>
 +
</div>
 +
</div>
 +
 
 +
==PatchOperationAdd==
 +
Inserts the specified <code>value</code>s as a child node of the XML nodes targeted by the operation's <code>xpath</code>. By default, the new nodes will be inserted after any existing child nodes (<code>Append</code>). You can use <code><order>Prepend</order></code> in the patch operation to insert them before existing child nodes instead.
 +
 
 +
Note: PatchOperationAdd will not overwrite any existing tags. If one of your <code>value</code>s overlaps with an existing node and you are not targeting a list node, then it will cause an error on game load.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>SampleDef</defName>
 +
  <aaa>Some text</aaa>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAdd">
 +
  <xpath>Defs/ExampleDef[defName="SampleDef"]</xpath>
 +
  <value>
 +
    <bbb>New text</bbb>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>SampleDef</defName>
 +
  <aaa>Some text</aaa>
 +
  <bbb>New text</bbb>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>SampleDef</defName>
 +
  <exampleList>
 +
    <li>Bar</li>
 +
  </exampleList>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAdd">
 +
  <xpath>Defs/ExampleDef[defName="SampleDef"]/exampleList</xpath>
 +
  <order>Prepend</order>
 +
  <value>
 +
    <li>Foo</li>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>SampleDef</defName>
 +
  <exampleList>
 +
    <li>Foo</li>
 +
    <li>Bar</li>
 +
  </exampleList>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationInsert==
 +
Inserts the specified <code>value</code>s as a sibling above the selected node(s). You can specify <code><order>Append</order></code> to insert it after the targeted node(s) instead (default is <code>Prepend</code>).
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Rainbow</defName>
 +
  <colors>
 +
    <li>Red</li>
 +
    <li>Yellow</li>
 +
    <li>Green</li>
 +
    <li>Blue</li>
 +
    <li>Violet</li>
 +
  </colors>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationInsert">
 +
  <xpath>Defs/ExampleDef[defName="Rainbow"]/colors/li[text()="Yellow"]</xpath>
 +
  <value>
 +
    <li>Orange</li>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Rainbow</defName>
 +
  <colors>
 +
    <li>Red</li>
 +
    <li>Orange</li>
 +
    <li>Yellow</li>
 +
    <li>Green</li>
 +
    <li>Blue</li>
 +
    <li>Violet</li>
 +
  </colors>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Fish</defName>
 +
  <lines>
 +
    <li>one fish</li>
 +
    <li>two fish</li>
 +
  </lines>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationInsert">
 +
  <xpath>Defs/ExampleDef[defName="Fish"]/lines/li[text()="two fish"]</xpath>
 +
  <order>Append</order>
 +
  <value>
 +
    <li>red fish</li>
 +
    <li>blue fish</li>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Fish</defName>
 +
  <lines>
 +
    <li>one fish</li>
 +
    <li>two fish</li>
 +
    <li>red fish</li>
 +
    <li>blue fish</li>
 +
  </lines>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationRemove==
 +
Removes the targeted node.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationRemove">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]/bar</xpath>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationReplace==
 +
Replaces the selected node(s) with your <code>value</code>s.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationReplace">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]/baz</xpath>
 +
  <value>
 +
    <baz>Drei</baz>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Drei</baz>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationAttributeAdd==
 +
Adds the specified attribute to the targeted node(s), but only if that attribute is not yet present.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAttributeAdd">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
 +
  <attribute>Name</attribute>
 +
  <value>SampleBase</value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleBase">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationAttributeSet==
 +
Adds the specified attribute to the targeted node(s), or overwrites the existing value if the specified attribute already exists.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleSource">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAttributeSet">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
 +
  <attribute>Name</attribute>
 +
  <value>SampleBase</value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleBase">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationAttributeRemove==
 +
Removes the specified attribute from the targeted node(s).
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleBase">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAttributeRemove">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
 +
  <attribute>Name</attribute>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef>
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationAddModExtension==
 +
{{Main|Modding Tutorials/DefModExtension}}
 +
Adds the specified [[Modding Tutorials/DefModExtension|DefModExtension]] to the targeted <code>Def</code>. Automatically creates a <code><modExtensions></code> node if one doesn't already exist.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleBase">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
</ExampleDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationAddModExtension">
 +
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
 +
  <value>
 +
    <li Class="MyNamespace.MyModExtension">
 +
      <key>Value</key>
 +
    </li>
 +
  </value>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ExampleDef Name="SampleBase">
 +
  <defName>Sample</defName>
 +
  <foo>Uno</foo>
 +
  <bar>Dos</bar>
 +
  <baz>Tres</baz>
 +
  <modExtensions>
 +
    <li Class="MyNamespace.MyModExtension">
 +
      <key>Value</key>
 +
    </li>
 +
  </modExtensions>
 +
</ExampleDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationSetName==
 +
Changes the name of a node. Most useful for changing the names of the nodes in "dictionary"-style nodes without changing their contents, such as for stat blocks or recipe products.
 +
 
 +
<div class="TutorialTableWrapper">
 +
{| class="TutorialCodeTable"
 +
! Before !! Patch operation || After
 +
|-
 +
| <source lang="xml">
 +
<ThingDef>
 +
  <defName>ExampleThing</defName>
 +
  <!-- many nodes omitted -->
 +
  <statBases>
 +
    <Insulation_Cold>10</Insulation_Cold>
 +
  </statBases>
 +
</ThingDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationSetName">
 +
  <xpath>Defs/ThingDef[defName="ExampleThing"]/statBases/Insulation_Cold</xpath>
 +
  <name>Insulation_Heat</name>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<ThingDef>
 +
  <defName>ExampleRecipe</defName>
 +
  <!-- many nodes omitted -->
 +
  <statBases>
 +
    <Insulation_Heat>10</Insulation_Heat>
 +
  </statBases>
 +
</ThingDef>
 +
</source>
 +
|-
 +
| <source lang="xml">
 +
<RecipeDef>
 +
  <defName>ExampleRecipe</defName>
 +
  <!-- many nodes omitted -->
 +
  <products>
 +
    <WoodLog>30</WoodLog>
 +
  </products>
 +
</RecipeDef>
 +
</source>
 +
| class="TutorialCodeTable-highlighted" |<source lang="xml">
 +
<Operation Class="PatchOperationSetName">
 +
  <xpath>Defs/RecipeDef[defName="ExampleRecipe"]/products/WoodLog</xpath>
 +
  <name>Steel</name>
 +
</Operation>
 +
</source>
 +
| <source lang="xml">
 +
<RecipeDef>
 +
  <defName>ExampleRecipe</defName>
 +
  <!-- many nodes omitted -->
 +
  <products>
 +
    <Steel>30</Steel>
 +
  </products>
 +
</RecipeDef>
 +
</source>
 +
|-
 +
|}
 +
</div>
 +
 
 +
==PatchOperationSequence==
 +
Contains one or more additional PatchOperations, which are executed in order. If any of them fail, then the Sequence stops and will not run any additional PatchOperations.
 +
 
 +
'''WARNING''': PatchOperations within an XML file will run in order even without a PatchOperationSequence and using a PatchOperationSequence can obfuscate or hide errors, making it difficult to debug if your child PatchOperations have errors. Do not use PatchOperationSequence unless you are sequencing multiple PatchOperations with a single PatchOperationConditional or PatchOperationFindMod or you are using MayRequire on child PatchOperations, and even then it's strongly recommended you write your PatchOperations as independent <code>Operation</code>s first to ensure they are working as intended.
  
 
<source lang="xml">
 
<source lang="xml">
−
   <Operation Class="PatchOperationReplace">
+
<Operation Class="PatchOperationSequence">
−
<xpath>*/TerrainDef[defName="WaterDeep"]/texturePath</xpath>
+
  <operations>
−
<value><texturePath>Your/Texture/Path/Here</texturePath></value>
+
    <li Class="PatchOperationAdd">
 +
      <xpath>Defs/ExampleDef[defName="Sample"]/statBases</xpath>
 +
      <value>
 +
        <Mass>10</Mass>
 +
      </value>
 +
    </li>
 +
    <li Class="PatchOperationSetName">
 +
      <xpath>Defs/ExampleDef[defName="Sample"]/statBases/Flammability</xpath>
 +
      <name>ToxicEnvironmentResistance</name>
 +
    </li>
 +
    <!-- etc -->
 +
  </operations>
 +
</Operation>
 +
</source>
 +
 
 +
As mentioned, you can use [[Modding_Tutorials/MayRequire|MayRequire]] on child operations of a PatchOperationSequence, but you should test them individually before adding them to said Sequence:
 +
 
 +
<source lang="xml">
 +
<Operation Class="PatchOperationSequence">
 +
  <operations>
 +
    <li Class="PatchOperationAdd" MayRequire="Ludeon.Rimworld.Biotech"> <!-- Only runs if Biotech is active -->
 +
      <xpath>Defs/ThingDef[defName="MechGestator"]/recipes</xpath>
 +
      <value>
 +
        <li>MyCustomMech</li>
 +
      </value>
 +
    </li>
 +
    <li Class="PatchOperationAdd" MayRequire="MyProject.OtherModPackageId"><!-- Only runs if the specific mod is active -->
 +
      <xpath>Defs/ThingDef[defName="OtherModWorkbench"]/recipes</xpath>
 +
      <value>
 +
        <li>MyCustomResource</li>
 +
      </value>
 +
    </li>
 +
  </operations>
 +
</Operation>
 +
</source>
 +
 
 +
==PatchOperationFindMod==
 +
 
 +
Checks whether any of the specified mods or DLCs are loaded and allows you to run an additional PatchOperation for <code>match</code> or <code>nomatch</code> results.
 +
 
 +
'''WARNING''': Unlike all other mod-compatibility features in RimWorld, PatchOperationFindMod uses the mod ''name'' and not its <code>packageId</code>.
 +
 
 +
'''NOTE''': For expansions, PatchOperationFindMod uses the <code>label</code> value defined in the <code>ExpansionDef</code> for the DLC.  At present, this means they are identified by just their single word names: Royalty, Ideology, Biotech, Anomaly.
 +
 
 +
'''NOTE''': PatchOperationFindMod should only be used if you are implementing ''optional'' compatibility for the target mod, i.e. if your mod can work with or without the mod in question. If you are creating a compatibility mod specifically for a target mod that would be meaningless without that mod present, then it's better to simply specify that mod in your About.xml as a dependency and forgo the use of PatchOperationFindMod and avoid the potential issues introduced by using PatchOperationSequence.
 +
 
 +
The following example adds a mod extension to the targeted Defs if RimQuest is loaded ([https://github.com/Mehni/MoreFactionInteraction/blob/ab3ab2a22ee529ee4e38a471fe150fd48fd07ce9/Patches/MoreFactionInteraction.xml#L64 See original]):
 +
<source lang="xml">
 +
<Operation Class="PatchOperationFindMod">
 +
  <mods>
 +
    <li>RimQuest</li>
 +
  </mods>
 +
  <match Class="PatchOperationAddModExtension">
 +
    <xpath>Defs/IncidentDef[defName="MFI_DiplomaticMarriage" or defName="MFI_HuntersLodge" or defName="MFI_Quest_PeaceTalks"]</xpath>
 +
    <value>
 +
      <li Class = "RimQuest.RimQuest_ModExtension">
 +
        <canBeARimQuest>false</canBeARimQuest>
 +
      </li>
 +
    </value>
 +
   </match>
 +
</Operation>
 +
</source>
 +
 
 +
The following example replaces the tabWindowClass of the Factions button when Relations Tab is '''not''' loaded:
 +
<source lang ="xml">
 +
<Operation Class="PatchOperationFindMod">
 +
  <mods>
 +
    <li>Relations Tab</li>
 +
  </mods>
 +
  <nomatch Class="PatchOperationReplace">
 +
    <xpath>/Defs/MainButtonDef[defName="Factions"]/tabWindowClass</xpath>
 +
    <value>
 +
      <tabWindowClass>MyNameSpace.MyTabWindowClass</tabWindowClass>
 +
    </value>
 +
  </nomatch>
 +
</Operation>
 +
</source>
 +
 
 +
==PatchOperationConditional==
 +
 
 +
Tests for the existence/validity of the specified node(s) and allows you to run optional <code>match</code> or <code>nomatch</code> PatchOperations in response.
 +
 
 +
The following example adds a <code><comps></code> node to the Caravan Def if it does not exist already, then adds a custom comp to said list:
 +
<source lang ="xml">
 +
<?xml version="1.0" encoding="utf-8" ?>
 +
<Patch>
 +
 
 +
  <!-- add comps field to Caravan WorldObjectDef if it doesn't exist -->
 +
  <Operation Class="PatchOperationConditional">
 +
    <xpath>Defs/WorldObjectDef[defName="Caravan"]/comps</xpath>
 +
    <nomatch Class="PatchOperationAdd">
 +
      <xpath>Defs/WorldObjectDef[defName="Caravan"]</xpath>
 +
      <value>
 +
        <comps />
 +
      </value>
 +
    </nomatch>
 +
  </Operation>
 +
 
 +
  <!-- add pyromaniac caravan handler comp to Caravan WorldObjectDef -->
 +
  <Operation Class="PatchOperationAdd">
 +
    <xpath>Defs/WorldObjectDef[defName="Caravan"]/comps</xpath>
 +
    <value>
 +
      <li Class="BetterPyromania.WorldObjectCompProperties_Pyromania">
 +
        <fuelCount>20</fuelCount>
 +
        <cooldown>30000</cooldown>
 +
        <needThreshold>0.5</needThreshold>
 +
      </li>
 +
    </value>
 
   </Operation>
 
   </Operation>
 +
 +
</Patch>
 
</source>
 
</source>
  
−
== Overview of available PatchOperations ==
+
==PatchOperationTest==
−
There are 11 available PatchOperation types:
 
  
−
* Four do basic operations on XML nodes:
+
{{:Modding_Tutorials/Obsolete}}
−
** '''[[#PatchOperationAdd|PatchOperationAdd]]''' adds a provided child node to the selected node
 
−
** '''[[#PatchOperationInsert|PatchOperationInsert]]''' adds a provided sibling node to the selected node
 
−
** '''[[#PatchOperationRemove|PatchOperationRemove]]''' deletes the selected node
 
−
** '''[[#PatchOperationReplace|PatchOperationReplace]]''' replaces the selected node with the provided node
 
−
* Three do basic operations on XML attributes:
 
−
** '''[[#PatchOperationAttributeAdd|PatchOperationAttributeAdd]]''' adds a provided attribute to the selected node if and only if the attribute name is not already present
 
−
** '''[[#PatchOperationAttributeSet|PatchOperationAttributeSet]]''' sets a provided attribute for the selected node, overwriting the attribute value if the attribute name is already present
 
−
** '''[[#PatchOperationAttributeRemove|PatchOperationAttributeSet]]''' removes an attribute for the selected node
 
−
* Four allow for more complex operations:
 
−
** '''[[#PatchOperationAddModExtension|PatchOperationAddModExtension]]''' adds a ModExtension.
 
−
** '''[[#PatchOperationSetName|PatchOperationSetName]]''' changes the name of a node. It is generally useless.
 
−
** '''[[#PatchOperationSequence|PatchOperationSequence]]''' contains a set of other PatchOperations, and aborts upon any operation failing
 
−
** '''[[#PatchOperationTest|PatchOperationTest]]''' tests nodes, which is useful inside a PatchOperationSequence
 
  
−
==XPath syntax==
+
Tests for the existence/validity of an xpath. Useful as a way to intentionally stop a PatchOperationSequence.
−
Each PatchOperation must specify an XML node to modify. It uses XPaths to specify them. An XPath is a "path" for the patch to follow when trying to find XML nodes matching the description. It will follow each part of the path from left to right.
 
  
−
Most XPaths should start with <code>*/</code>. The <code>*</code> matches any element, so it'll match the root (the top level) of the XML tree. The following slash selects  Using <code>//</code> is technically also valid, but because that construct selects ''all'' the elements in the XML tree, it's an expensive operation that makes a mod needlessly slow to load.
+
'''NOTE: Conditionally applying patches in this way is considered obsolete.''' Using PatchOperationConditional is a much better idea as the use of <success>Always</success> here will also suppress legitimate errors, making Sequences difficult to debug.
  
−
Once the root is selected, the XPath lets the system walk down specific branches of the tree. If we use the example from the lead, we get a specific path:
+
The following example patch is from Apparello, by Shinzy.  
 +
<source lang ="xml">
 +
<Operation Class="PatchOperationSequence">
 +
  <!-- Must use <success>Always</success> because of the PatchOperationTest -->
 +
  <success>Always</success>
 +
  <!-- check for worn graphics and if none found, add one -->
 +
  <operations>
 +
    <li Class="PatchOperationTest">
 +
      <xpath>Defs/ThingDef[defName = "Apparel_Pants"]/apparel/wornGraphicPath</xpath>
 +
      <success>Invert</success>
 +
    </li>
 +
    <li Class="PatchOperationAdd">
 +
      <xpath>Defs/ThingDef[defName = "Apparel_Pants"]/apparel</xpath>
 +
      <value>
 +
        <wornGraphicPath>Accessorello/Pants/Pants</wornGraphicPath>
 +
      </value>
 +
    </li>
 +
  </operations>
 +
</Operation>
 +
</source>
  
−
<code>*/TerrainDef[defName="WaterDeep"]/texturePath</code>
+
= Miscellaneous =
 +
 
 +
== Custom PatchOperations ==
 +
Custom PatchOperation types can be created in C# by subclassing <code>Verse.PatchOperation</code>, which is useful for performing a patch based on ModSettings values or other custom behavior.
 +
 
 +
A tutorial for this process does not exist yet, but you can check out the following references of custom PatchOperations:
 +
* [https://github.com/15adhami/XmlExtensions XML Extensions] - An entire framework mod containing many useful custom PatchOperations.
 +
* [https://github.com/CombatExtended-Continued/CombatExtended/blob/Development/Source/CombatExtended/CombatExtended/PatchOperationMakeGunCECompatible.cs PatchOperationMakeGunCECompatible] - Used by Combat Extended to automatically apply multiple changes to a single firearm for compatibility.
 +
* [https://gist.github.com/Lanilor/e326e33e268e78f68a2f5cd3cdbbe8c0 PatchOperationAddOrReplace] - An example of a custom variant of PatchOperationAdd that replaces an existing value.</br>
 +
 
 +
== "Success" Option ==
 +
 
 +
{{:Modding_Tutorials/Obsolete}}
 +
 
 +
The ''<code><success>...</success></code>'' node determines how errors are handled, usually in a PatchOperationSequence. '''Note that use of this tag should be considered obsolete'''; its use was common before PatchOperationConditional was implemented, but it should no longer be required and can cause confusion as it can suppress legitimate errors from showing up.
 +
 
 +
Options available are:
 +
* Always - This patch operation always succeeds, i.e. it suppresses all errors that might have occurred. This used to be used in PatchOperationSequence along with PatchOperationTest in order to conditionally run patches, but is now obsolete.
 +
* Normal - Errors are handled normally
 +
* Invert - Errors are considered a success and success is considered a failure. This used to be used in PatchOperationSequences to test the negative of a PatchOperationTest; you should now use <code><nomatch></code> on PatchOperationConditional.
 +
* Never - This patch operation always fails. Generally only used in testing to see if a Sequence is working correctly, should never be used in published mods.
 +
 
 +
=== Extenuating circumstances for "Success" ===
 +
There are, in very specific circumstances, a valid reason to use a <code><success>Always</success></code> statement.
 +
 
 +
For instance, consider the following opening lines for a Patch: <pre>
 +
<Operation Class="PatchOperationConditional">
 +
<xpath>/Defs/JoyKindDef[defName="Sierra_Drinking_Milkshake"]</xpath>
 +
<match Class="PatchOperationReplace">
 +
<success">Always</success>
 +
<xpath>/Defs/ThingDef[defName = "Laban" or defName = "AmbrosiaLaban" or defName = "ChocolateLaban" or defName = "StrawberryLaban" or defName = "MedicinalLaban"]/ingestible/joyKind</xpath>
 +
<value>
 +
<joyKind>Sierra_Drinking_Milkshake</joyKind>
 +
</value>
 +
</match>
 +
</Operation>
 +
</pre>
 +
 
 +
This Patch detects if a specific Mod's Joy Kind Def exists and, if it does, changes the Recreation Type received by consuming a Thing Def from another Mod; the Patch exists in neither Mod's folder, coming from a third-party Mod that is completely separate.
 +
 
 +
"Sierra Drinking Milkshake" (<code>"Sierra_Drinking_Milkshake"</code>) is added by the [https://steamcommunity.com/sharedfiles/filedetails/?id=2595980371 Milkshake Digital Deluxe Mod], and Laban (<code>"Laban"</code>) is added by the [https://steamcommunity.com/sharedfiles/filedetails/?id=2595938070 Laban Mod].
 +
 
 +
Now, imagine that neither the author of the Laban Mod or the Milkshake Mod created this Patch. Instead, a fan of both Mods included this in a compilation of Patches that alters dozens of Mods.
 +
 
 +
This Patch is in a third-party Mod that is neither of the constituent Mods that it patches. If a player had the Milkshake Mod loaded loaded, but ''did not'' have the Laban Mod, this Patch would attempt to to change the Joy Kind Def of consuming Laban to something that does not exist, and would cause the Laban Thing Def to cause errors when consumed, ''and'' cause the Patch to fail.
 +
 
 +
Therefore, because a large third-party Patch has to patch two Mods that it is not integrated with directly, and uploading a single Patch as a single Mod versus a compilation is inefficient, then it must be concluded that using "<code><success>Always</success></code>" '''''is acceptable in this extenuating circumstance'''''.
 +
 
 +
Outside of situations like this, using the "Success" statement is still not recommended.
 +
 
 +
== Tips and Tricks ==
 +
* Patching is run after all XML Defs are loaded into memory and in mod list order. If you are encountering compatibility issues with another mod's PatchOperations, you can use <code>loadBefore</code> and <code>loadAfter</code> in your <code>About.xml</code> to help players resolve these issues.
 +
* Patching is done before Def inheritance takes place. This means that you cannot target tags that are inherited from a parent, but also that if you alter a parent, all of its children will inherit the patched value.
 +
* You can override a value inherited from a parent Def without changing that value for all Defs by using <code>Inherit="False"</code>:
 +
<source lang = "xml">
 +
<Operation Class="PatchOperationAdd">
 +
  <xpath>/Defs/ThingDef[defName = "Apparel_KidPants"]</xpath>
 +
  <value>
 +
    <thingCategories Inherit="False">
 +
      <li>NewValue</li>
 +
    </thingCategories>
 +
  </value>
 +
</Operation>
 +
</source>
 +
* You can use <code>or</code> in predicates to target multiple nodes: <code>Defs/ThingDef[defName="Cassowary" or defName = "Emu" or defName = "Ostrich" or defName = "Turkey"]</code> This is generally better than using multiple PatchOperations so long as you are making the same changes to each target.
 +
* You can use <code>/text()</code> to target the text contents of a tag instead of the whole tag for operations like PatchOperationReplace. This is especially useful if you do not want to accidentally remove attributes.
  
−
# The root node is selected
+
== Common Issues / Troubleshooting ==
−
# All child nodes of the root node called "TerrainDef" are selected
 
−
# We narrow down from "all TerrainDefs" to only those with the child "defName" node whose value is "WaterDeep", which should give us exactly one node because defNames must be unique
 
−
# We select the child node "texturePath" from this node
 
  
−
==Overview of individual PatchOperations==
+
* XPath and XML nodes in general is case-sensitive and must be exact. Copying values such as <code>defName</code> fields is strongly recommended to avoid errors.
−
(to do)
+
* Malformed XML such as unclosed or mismatched tags can cause the XML parser to crash completely, which can result in a blank screen on startup or a "Recovered from a fatal error" screen and the removal of all active mods. If this occurs, run all of your XML through an XML validator to ensure that it is structurally correct. Checking your Player.log file can help in diagnosing the exact cause as well.
−
===PatchOperationAdd===
+
* It's very easy to confuse Insert vs Add; Insert will "add" the <code>value</code> as a ''sibling'' of the target node(s), while Add will "insert" the <code>value</code> as a ''child'' of the target node(s).
−
===PatchOperationInsert===
+
* Remember that XPath targets the XML data structure, not the file path.
−
===PatchOperationRemove===
+
* Nodes in XML other than <code>li</code> list items must be unique at each level. If you Add or Insert a duplicate node, that will generate a red error on load and cause that Def to fail to load.
−
===PatchOperationReplace===
+
* If you're still stumped, feel free to join the [https://discord.gg/RimWorld RimWorld Discord server] and ask questions in the <code>#mod-development</code> channel.
−
===PatchOperationAttributeAdd===
 
−
===PatchOperationAttributeSet===
 
−
===PatchOperationAttributeRemove===
 
−
===PatchOperationAddModExtension===
 
−
===PatchOperationSetName===
 
−
===PatchOperationSequence===
 
−
===PatchOperationTest===
 
  
−
== Resources ==
+
== References and Links ==
  
−
The best tutorial on PatchOperations created by Zhentar: [https://gist.github.com/Zhentar/4a1b71cea45b9337f70b30a21d868782 Introduction to PatchOperation]
+
{{:Modding_Tutorials/Obsolete}}
  
−
You can also learn about XPaths here: [https://www.w3schools.com/xml/xpath_intro.asp XPath tutorial]
+
The original tutorial on PatchOperations created by Zhentar: [https://gist.github.com/Zhentar/4a1b71cea45b9337f70b30a21d868782 Introduction to PatchOperation]
  
−
There is also an [https://github.com/roxxploxx/RimWorldModGuide/wiki/SHORTTUTORIAL:-DefPatches Overview of PatchOperations] on the [https://github.com/roxxploxx/RimWorldModGuide/wiki RimWorldModGuide].
+
[[Category:Modding]]
 +
[[Category:Modding tutorials]]

Latest revision as of 01:01, 14 July 2024

< Modding Tutorials

PatchOperations are a feature that allows you to modify the content of XML Defs. Prior to RimWorld alpha 17, modders could only modify Defs by creating new ones that overwrote the original; this often resulted in compatibility issues as if more than one mod tried to overwrite the same Def, only the last mod in the load order would succeed as prior ones would themselves be overwritten.

Basics[edit]

PatchOperations are written as XML nodes that go into your mod's Patches folder: 

MyModFolder
├ About
├ Defs
└ Patches
  └ MyPatchFile.xml

Just as with XML Defs, folder and file names do not matter and you can freely name and organize your patch files in whatever manner you wish. Individual patches themselves are a standard XML file with <Patch> as the root tag: 

<?xml version="1.0" encoding="utf-8"?>
<Patch>

  <!-- PatchOperations go here -->

</Patch>

XPath[edit]

Most PatchOperations must be targeted at one or more XML nodes inside the master XML document. This is done via XML Path Language or XPath.

Note that an XPath is targeting the structure of the XML document after it's been parsed by RimWorld's parser, thus it has nothing to do with the actual file or folder paths. For example, if you wanted to add a stat value to the vanilla Wall building, you might use an XPath like so:

Defs/ThingDef[defName="Wall"]/statBases

  • The first segment of any XPath targeting an XML Def will be Defs/ as all XML Defs use the <Defs> root tag.
  • The square brackets denote a predicate, or conditional match. In this case, we are looking for ThingDefs that have a child tag defName equal to "Wall".

Targeting Attributes[edit]

You can target Defs that do not have a defName (such as abstract bases) by targeting their identifying attributes. For example, if you wanted to add another Stuff category to the abstract base Def for all shelves, you might use the following xpath:

Defs/ThingDef[@Name="ShelfBase"]/stuffCategories

You can use the same technique to target all Defs that inherit from a common base. For example, you could use the following xpath to target all ThingDefs that inherit from ApparelBase:

Defs/ThingDef[@ParentName="ApparelBase"]

Additional XPath Resources[edit]

PatchOperation Types[edit]

Basic XML node operations:
XML attribute operations:
Special operations:
Conditional operations:

PatchOperationAdd[edit]

Inserts the specified values as a child node of the XML nodes targeted by the operation's xpath. By default, the new nodes will be inserted after any existing child nodes (Append). You can use <order>Prepend</order> in the patch operation to insert them before existing child nodes instead.

Note: PatchOperationAdd will not overwrite any existing tags. If one of your values overlaps with an existing node and you are not targeting a list node, then it will cause an error on game load.

Before Patch operation After 
<ExampleDef>
  <defName>SampleDef</defName>
  <aaa>Some text</aaa>
</ExampleDef>
 
<Operation Class="PatchOperationAdd">
  <xpath>Defs/ExampleDef[defName="SampleDef"]</xpath>
  <value>
    <bbb>New text</bbb>
  </value>
</Operation>
 
<ExampleDef>
  <defName>SampleDef</defName>
  <aaa>Some text</aaa>
  <bbb>New text</bbb>
</ExampleDef>
<ExampleDef>
  <defName>SampleDef</defName>
  <exampleList>
    <li>Bar</li>
  </exampleList>
</ExampleDef>
 
<Operation Class="PatchOperationAdd">
  <xpath>Defs/ExampleDef[defName="SampleDef"]/exampleList</xpath>
  <order>Prepend</order>
  <value>
    <li>Foo</li>
  </value>
</Operation>
 
<ExampleDef>
  <defName>SampleDef</defName>
  <exampleList>
    <li>Foo</li>
    <li>Bar</li>
  </exampleList>
</ExampleDef>

PatchOperationInsert[edit]

Inserts the specified values as a sibling above the selected node(s). You can specify <order>Append</order> to insert it after the targeted node(s) instead (default is Prepend).

Before Patch operation After 
<ExampleDef>
  <defName>Rainbow</defName>
  <colors>
    <li>Red</li>
    <li>Yellow</li>
    <li>Green</li>
    <li>Blue</li>
    <li>Violet</li>
  </colors>
</ExampleDef>
 
<Operation Class="PatchOperationInsert">
  <xpath>Defs/ExampleDef[defName="Rainbow"]/colors/li[text()="Yellow"]</xpath>
  <value>
    <li>Orange</li>
  </value>
</Operation>
 
<ExampleDef>
  <defName>Rainbow</defName>
  <colors>
    <li>Red</li>
    <li>Orange</li>
    <li>Yellow</li>
    <li>Green</li>
    <li>Blue</li>
    <li>Violet</li>
  </colors>
</ExampleDef>
<ExampleDef>
  <defName>Fish</defName>
  <lines>
    <li>one fish</li>
    <li>two fish</li>
  </lines>
</ExampleDef>
 
<Operation Class="PatchOperationInsert">
  <xpath>Defs/ExampleDef[defName="Fish"]/lines/li[text()="two fish"]</xpath>
  <order>Append</order>
  <value>
    <li>red fish</li>
    <li>blue fish</li>
  </value>
</Operation>
 
<ExampleDef>
  <defName>Fish</defName>
  <lines>
    <li>one fish</li>
    <li>two fish</li>
    <li>red fish</li>
    <li>blue fish</li>
  </lines>
</ExampleDef>

PatchOperationRemove[edit]

Removes the targeted node.

Before Patch operation After 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationRemove">
  <xpath>Defs/ExampleDef[defName="Sample"]/bar</xpath>
</Operation>
 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <baz>Tres</baz>
</ExampleDef>

PatchOperationReplace[edit]

Replaces the selected node(s) with your values.

Before Patch operation After 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationReplace">
  <xpath>Defs/ExampleDef[defName="Sample"]/baz</xpath>
  <value>
    <baz>Drei</baz>
  </value>
</Operation>
 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Drei</baz>
</ExampleDef>

PatchOperationAttributeAdd[edit]

Adds the specified attribute to the targeted node(s), but only if that attribute is not yet present.

Before Patch operation After 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationAttributeAdd">
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
  <attribute>Name</attribute>
  <value>SampleBase</value>
</Operation>
 
<ExampleDef Name="SampleBase">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>

PatchOperationAttributeSet[edit]

Adds the specified attribute to the targeted node(s), or overwrites the existing value if the specified attribute already exists.

Before Patch operation After 
<ExampleDef Name="SampleSource">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationAttributeSet">
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
  <attribute>Name</attribute>
  <value>SampleBase</value>
</Operation>
 
<ExampleDef Name="SampleBase">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>

PatchOperationAttributeRemove[edit]

Removes the specified attribute from the targeted node(s).

Before Patch operation After 
<ExampleDef Name="SampleBase">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationAttributeRemove">
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
  <attribute>Name</attribute>
</Operation>
 
<ExampleDef>
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>

PatchOperationAddModExtension[edit]

Main article: Modding Tutorials/DefModExtension

Adds the specified DefModExtension to the targeted Def. Automatically creates a <modExtensions> node if one doesn't already exist.

Before Patch operation After 
<ExampleDef Name="SampleBase">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
</ExampleDef>
 
<Operation Class="PatchOperationAddModExtension">
  <xpath>Defs/ExampleDef[defName="Sample"]</xpath>
  <value>
    <li Class="MyNamespace.MyModExtension">
      <key>Value</key>
    </li>
  </value>
</Operation>
 
<ExampleDef Name="SampleBase">
  <defName>Sample</defName>
  <foo>Uno</foo>
  <bar>Dos</bar>
  <baz>Tres</baz>
  <modExtensions>
    <li Class="MyNamespace.MyModExtension">
      <key>Value</key>
    </li>
  </modExtensions>
</ExampleDef>

PatchOperationSetName[edit]

Changes the name of a node. Most useful for changing the names of the nodes in "dictionary"-style nodes without changing their contents, such as for stat blocks or recipe products.

Before Patch operation After 
<ThingDef>
  <defName>ExampleThing</defName>
  <!-- many nodes omitted -->
  <statBases>
    <Insulation_Cold>10</Insulation_Cold>
  </statBases>
</ThingDef>
 
<Operation Class="PatchOperationSetName">
  <xpath>Defs/ThingDef[defName="ExampleThing"]/statBases/Insulation_Cold</xpath>
  <name>Insulation_Heat</name>
</Operation>
 
<ThingDef>
  <defName>ExampleRecipe</defName>
  <!-- many nodes omitted -->
  <statBases>
    <Insulation_Heat>10</Insulation_Heat>
  </statBases>
</ThingDef>
<RecipeDef>
  <defName>ExampleRecipe</defName>
  <!-- many nodes omitted -->
  <products>
    <WoodLog>30</WoodLog>
  </products>
</RecipeDef>
 
<Operation Class="PatchOperationSetName">
  <xpath>Defs/RecipeDef[defName="ExampleRecipe"]/products/WoodLog</xpath>
  <name>Steel</name>
</Operation>
 
<RecipeDef>
  <defName>ExampleRecipe</defName>
  <!-- many nodes omitted -->
  <products>
    <Steel>30</Steel>
  </products>
</RecipeDef>

PatchOperationSequence[edit]

Contains one or more additional PatchOperations, which are executed in order. If any of them fail, then the Sequence stops and will not run any additional PatchOperations.

WARNING: PatchOperations within an XML file will run in order even without a PatchOperationSequence and using a PatchOperationSequence can obfuscate or hide errors, making it difficult to debug if your child PatchOperations have errors. Do not use PatchOperationSequence unless you are sequencing multiple PatchOperations with a single PatchOperationConditional or PatchOperationFindMod or you are using MayRequire on child PatchOperations, and even then it's strongly recommended you write your PatchOperations as independent Operations first to ensure they are working as intended. 

<Operation Class="PatchOperationSequence">
  <operations>
    <li Class="PatchOperationAdd">
      <xpath>Defs/ExampleDef[defName="Sample"]/statBases</xpath>
      <value>
        <Mass>10</Mass>
      </value>
    </li>
    <li Class="PatchOperationSetName">
      <xpath>Defs/ExampleDef[defName="Sample"]/statBases/Flammability</xpath>
      <name>ToxicEnvironmentResistance</name>
    </li>
    <!-- etc -->
  </operations>
</Operation>

As mentioned, you can use MayRequire on child operations of a PatchOperationSequence, but you should test them individually before adding them to said Sequence: 

<Operation Class="PatchOperationSequence">
  <operations>
    <li Class="PatchOperationAdd" MayRequire="Ludeon.Rimworld.Biotech"> <!-- Only runs if Biotech is active -->
      <xpath>Defs/ThingDef[defName="MechGestator"]/recipes</xpath>
      <value>
        <li>MyCustomMech</li>
      </value>
    </li>
    <li Class="PatchOperationAdd" MayRequire="MyProject.OtherModPackageId"><!-- Only runs if the specific mod is active -->
      <xpath>Defs/ThingDef[defName="OtherModWorkbench"]/recipes</xpath>
      <value>
        <li>MyCustomResource</li>
      </value>
    </li>
  </operations>
</Operation>

PatchOperationFindMod[edit]

Checks whether any of the specified mods or DLCs are loaded and allows you to run an additional PatchOperation for match or nomatch results.

WARNING: Unlike all other mod-compatibility features in RimWorld, PatchOperationFindMod uses the mod name and not its packageId.

NOTE: For expansions, PatchOperationFindMod uses the label value defined in the ExpansionDef for the DLC. At present, this means they are identified by just their single word names: Royalty, Ideology, Biotech, Anomaly.

NOTE: PatchOperationFindMod should only be used if you are implementing optional compatibility for the target mod, i.e. if your mod can work with or without the mod in question. If you are creating a compatibility mod specifically for a target mod that would be meaningless without that mod present, then it's better to simply specify that mod in your About.xml as a dependency and forgo the use of PatchOperationFindMod and avoid the potential issues introduced by using PatchOperationSequence.

The following example adds a mod extension to the targeted Defs if RimQuest is loaded (See original): 

<Operation Class="PatchOperationFindMod">
  <mods>
    <li>RimQuest</li>
  </mods>
  <match Class="PatchOperationAddModExtension">
    <xpath>Defs/IncidentDef[defName="MFI_DiplomaticMarriage" or defName="MFI_HuntersLodge" or defName="MFI_Quest_PeaceTalks"]</xpath>
    <value>
      <li Class = "RimQuest.RimQuest_ModExtension">
        <canBeARimQuest>false</canBeARimQuest>
      </li>
    </value>
  </match>
</Operation>

The following example replaces the tabWindowClass of the Factions button when Relations Tab is not loaded: 

<Operation Class="PatchOperationFindMod">
  <mods>
    <li>Relations Tab</li>
  </mods>
  <nomatch Class="PatchOperationReplace">
    <xpath>/Defs/MainButtonDef[defName="Factions"]/tabWindowClass</xpath>
    <value>
      <tabWindowClass>MyNameSpace.MyTabWindowClass</tabWindowClass>
    </value>
  </nomatch>
</Operation>

PatchOperationConditional[edit]

Tests for the existence/validity of the specified node(s) and allows you to run optional match or nomatch PatchOperations in response.

The following example adds a <comps> node to the Caravan Def if it does not exist already, then adds a custom comp to said list: 

<?xml version="1.0" encoding="utf-8" ?>
<Patch>

  <!-- add comps field to Caravan WorldObjectDef if it doesn't exist -->
  <Operation Class="PatchOperationConditional">
    <xpath>Defs/WorldObjectDef[defName="Caravan"]/comps</xpath>
    <nomatch Class="PatchOperationAdd">
      <xpath>Defs/WorldObjectDef[defName="Caravan"]</xpath>
      <value>
        <comps />
      </value>
    </nomatch>
  </Operation>

  <!-- add pyromaniac caravan handler comp to Caravan WorldObjectDef -->
  <Operation Class="PatchOperationAdd">
    <xpath>Defs/WorldObjectDef[defName="Caravan"]/comps</xpath>
    <value>
      <li Class="BetterPyromania.WorldObjectCompProperties_Pyromania">
        <fuelCount>20</fuelCount>
        <cooldown>30000</cooldown>
        <needThreshold>0.5</needThreshold>
      </li>
    </value>
  </Operation>

</Patch>

PatchOperationTest[edit]

!
Obsolete
The following content was written for a previous version of RimWorld or is otherwise no longer fully relevant today. Please be mindful of any potential inaccuracies.

Tests for the existence/validity of an xpath. Useful as a way to intentionally stop a PatchOperationSequence.

NOTE: Conditionally applying patches in this way is considered obsolete. Using PatchOperationConditional is a much better idea as the use of <success>Always</success> here will also suppress legitimate errors, making Sequences difficult to debug.

The following example patch is from Apparello, by Shinzy. 

<Operation Class="PatchOperationSequence">
  <!-- Must use <success>Always</success> because of the PatchOperationTest -->
  <success>Always</success>
  <!-- check for worn graphics and if none found, add one -->
  <operations>
    <li Class="PatchOperationTest">
      <xpath>Defs/ThingDef[defName = "Apparel_Pants"]/apparel/wornGraphicPath</xpath>
      <success>Invert</success>
    </li>
    <li Class="PatchOperationAdd">
      <xpath>Defs/ThingDef[defName = "Apparel_Pants"]/apparel</xpath>
      <value>
        <wornGraphicPath>Accessorello/Pants/Pants</wornGraphicPath>
      </value>
    </li>
  </operations>
</Operation>

Miscellaneous[edit]

Custom PatchOperations[edit]

Custom PatchOperation types can be created in C# by subclassing Verse.PatchOperation, which is useful for performing a patch based on ModSettings values or other custom behavior.

A tutorial for this process does not exist yet, but you can check out the following references of custom PatchOperations:

"Success" Option[edit]

!
Obsolete
The following content was written for a previous version of RimWorld or is otherwise no longer fully relevant today. Please be mindful of any potential inaccuracies.

The <success>...</success> node determines how errors are handled, usually in a PatchOperationSequence. Note that use of this tag should be considered obsolete; its use was common before PatchOperationConditional was implemented, but it should no longer be required and can cause confusion as it can suppress legitimate errors from showing up.

Options available are:

  • Always - This patch operation always succeeds, i.e. it suppresses all errors that might have occurred. This used to be used in PatchOperationSequence along with PatchOperationTest in order to conditionally run patches, but is now obsolete.
  • Normal - Errors are handled normally
  • Invert - Errors are considered a success and success is considered a failure. This used to be used in PatchOperationSequences to test the negative of a PatchOperationTest; you should now use <nomatch> on PatchOperationConditional.
  • Never - This patch operation always fails. Generally only used in testing to see if a Sequence is working correctly, should never be used in published mods.

Extenuating circumstances for "Success"[edit]

There are, in very specific circumstances, a valid reason to use a <success>Always</success> statement.

For instance, consider the following opening lines for a Patch: 

	<Operation Class="PatchOperationConditional">
		<xpath>/Defs/JoyKindDef[defName="Sierra_Drinking_Milkshake"]</xpath>
		<match Class="PatchOperationReplace">
			<success">Always</success>
			<xpath>/Defs/ThingDef[defName = "Laban" or defName = "AmbrosiaLaban" or defName = "ChocolateLaban" or defName = "StrawberryLaban" or defName = "MedicinalLaban"]/ingestible/joyKind</xpath>
			<value>
				<joyKind>Sierra_Drinking_Milkshake</joyKind>
			</value>
		</match>
	</Operation>

This Patch detects if a specific Mod's Joy Kind Def exists and, if it does, changes the Recreation Type received by consuming a Thing Def from another Mod; the Patch exists in neither Mod's folder, coming from a third-party Mod that is completely separate.

"Sierra Drinking Milkshake" ("Sierra_Drinking_Milkshake") is added by the Milkshake Digital Deluxe Mod, and Laban ("Laban") is added by the Laban Mod.

Now, imagine that neither the author of the Laban Mod or the Milkshake Mod created this Patch. Instead, a fan of both Mods included this in a compilation of Patches that alters dozens of Mods.

This Patch is in a third-party Mod that is neither of the constituent Mods that it patches. If a player had the Milkshake Mod loaded loaded, but did not have the Laban Mod, this Patch would attempt to to change the Joy Kind Def of consuming Laban to something that does not exist, and would cause the Laban Thing Def to cause errors when consumed, and cause the Patch to fail.

Therefore, because a large third-party Patch has to patch two Mods that it is not integrated with directly, and uploading a single Patch as a single Mod versus a compilation is inefficient, then it must be concluded that using "<success>Always</success>" is acceptable in this extenuating circumstance.

Outside of situations like this, using the "Success" statement is still not recommended.

Tips and Tricks[edit]

  • Patching is run after all XML Defs are loaded into memory and in mod list order. If you are encountering compatibility issues with another mod's PatchOperations, you can use loadBefore and loadAfter in your About.xml to help players resolve these issues.
  • Patching is done before Def inheritance takes place. This means that you cannot target tags that are inherited from a parent, but also that if you alter a parent, all of its children will inherit the patched value.
  • You can override a value inherited from a parent Def without changing that value for all Defs by using Inherit="False":
<Operation Class="PatchOperationAdd">
  <xpath>/Defs/ThingDef[defName = "Apparel_KidPants"]</xpath>
  <value>
    <thingCategories Inherit="False">
      <li>NewValue</li>
    </thingCategories>
  </value>
</Operation>
  • You can use or in predicates to target multiple nodes: Defs/ThingDef[defName="Cassowary" or defName = "Emu" or defName = "Ostrich" or defName = "Turkey"] This is generally better than using multiple PatchOperations so long as you are making the same changes to each target.
  • You can use /text() to target the text contents of a tag instead of the whole tag for operations like PatchOperationReplace. This is especially useful if you do not want to accidentally remove attributes.

Common Issues / Troubleshooting[edit]

  • XPath and XML nodes in general is case-sensitive and must be exact. Copying values such as defName fields is strongly recommended to avoid errors.
  • Malformed XML such as unclosed or mismatched tags can cause the XML parser to crash completely, which can result in a blank screen on startup or a "Recovered from a fatal error" screen and the removal of all active mods. If this occurs, run all of your XML through an XML validator to ensure that it is structurally correct. Checking your Player.log file can help in diagnosing the exact cause as well.
  • It's very easy to confuse Insert vs Add; Insert will "add" the value as a sibling of the target node(s), while Add will "insert" the value as a child of the target node(s).
  • Remember that XPath targets the XML data structure, not the file path.
  • Nodes in XML other than li list items must be unique at each level. If you Add or Insert a duplicate node, that will generate a red error on load and cause that Def to fail to load.
  • If you're still stumped, feel free to join the RimWorld Discord server and ask questions in the #mod-development channel.

References and Links[edit]

!
Obsolete
The following content was written for a previous version of RimWorld or is otherwise no longer fully relevant today. Please be mindful of any potential inaccuracies.

The original tutorial on PatchOperations created by Zhentar: Introduction to PatchOperation

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