Merge pull request #1 from HellButcher/main

cstettler · web-flow · commit 564b7f90d584 · 2026-01-09T18:54:33.000+01:00
diff --git a/README.md b/README.md
@@ -12,6 +12,7 @@ A dialect for Thymeleaf that enables reusable UI components with named slots and
 - Define reusable UI components
 - Support for default and named slots
 - Support for component parameters
+- Supports default values for component parameters
 - Simple integration with Thymeleaf into Spring
 
 ## Installation
@@ -57,9 +58,10 @@ When directly instantiating the template engine, set the component dialect using
 
 ```html
 <!-- src/main/resources/templates/components/card.html -->
-<th:block xmlns:th="http://www.thymeleaf.org" th:fragment="card(title)">
+<th:block xmlns:th="http://www.thymeleaf.org" th:fragment="card(title)" pl:subtitle="${null}">
   <div class="card">
     <div class="card-header" th:text="${title}">Card Title</div>
+    <div th:if="${subtitle}" class="card-subtitle" th:text="${subtitle}">Card Subtitle</div>
     <div class="card-body">
       <pl:slot>
         <!-- default slot -->
@@ -86,9 +88,13 @@ Do the same accordingly for the other components.
     <b>This will replace the footer slot content</b>
   </div>
 </pl:card>
+
+<pl:card pl:title="My Card" pl:subtitle="My Subtitle">
+  <div>This will replace the default slot content</div>
+</pl:card>
 ```
 
 ## License
 
 Thymeleaf Component Dialect is Open Source software released under the
-[Apache 2.0 license](http://www.apache.org/licenses/LICENSE-2.0.html).
+[Apache 2.0 license](http://www.apache.org/licenses/LICENSE-2.0.html).
diff --git a/src/main/java/ch/cstettler/thymeleaf/ComponentDialect.java b/src/main/java/ch/cstettler/thymeleaf/ComponentDialect.java
@@ -22,20 +22,23 @@
 
 public class ComponentDialect extends AbstractProcessorDialect {
 
-  private static final String DIALECT_PREFIX = "pl";
+  private static final String DEFAULT_DIALECT_PREFIX = "pl";
 
   private final Set<IProcessor> processors;
 
   public ComponentDialect() {
-    super("Thymeleaf UI Component Dialect", DIALECT_PREFIX, 0);
+    this(DEFAULT_DIALECT_PREFIX);
+  }
+
+  public ComponentDialect(String prefix) {
+    super("Thymeleaf UI Component Dialect", prefix, 0);
 
     this.processors = new HashSet<>();
-    this.processors.add(new RemoveSlotAttributeProcessor(DIALECT_PREFIX, "slot"));
+    this.processors.add(new RemoveSlotAttributeProcessor(prefix, "slot"));
   }
 
   public ComponentDialect addComponent(String elementName, String templatePath) {
-    processors.add(new ComponentModelProcessor(DIALECT_PREFIX, elementName, templatePath));
-
+    processors.add(new ComponentModelProcessor(getPrefix (), elementName, templatePath));
     return this;
   }
 
diff --git a/src/main/java/ch/cstettler/thymeleaf/ComponentModelProcessor.java b/src/main/java/ch/cstettler/thymeleaf/ComponentModelProcessor.java
@@ -23,9 +23,14 @@
 import static org.thymeleaf.templatemode.TemplateMode.HTML;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
 import org.thymeleaf.context.ITemplateContext;
 import org.thymeleaf.engine.TemplateManager;
 import org.thymeleaf.engine.TemplateModel;
@@ -36,6 +41,7 @@
 import org.thymeleaf.model.IModelFactory;
 import org.thymeleaf.model.IOpenElementTag;
 import org.thymeleaf.model.IProcessableElementTag;
+import org.thymeleaf.model.IStandaloneElementTag;
 import org.thymeleaf.model.ITemplateEvent;
 import org.thymeleaf.processor.element.AbstractElementModelProcessor;
 import org.thymeleaf.processor.element.IElementModelStructureHandler;
@@ -55,7 +61,7 @@ public ComponentModelProcessor(String dialectPrefix, String elementName, String
 
     this.dialectPrefix = dialectPrefix;
     this.elementName = elementName;
-    this.templatePath = templatePath;
+    this.templatePath = templatePath != null ? templatePath : dialectPrefix + "/" + elementName + "/" + elementName;
   }
 
   @Override
@@ -77,9 +83,15 @@ protected void doProcess(ITemplateContext context, IModel model, IElementModelSt
     componentAttributes.forEach(structureHandler::setLocalVariable);
 
     IModel fragmentModel = loadFragmentModel(context);
+    IProcessableElementTag fragmentRootElementTag = firstOpenElementTagWithAttribute(fragmentModel, "th:fragment");
+    if (fragmentRootElementTag != null) {
+      Map<String, Object> defaultAttributes = resolveComponentAttributes (fragmentRootElementTag, context, expressionParser);
+      componentAttributes.keySet ().forEach (defaultAttributes::remove);
+      defaultAttributes.forEach (structureHandler::setLocalVariable);
+    }
     Map<String, List<ITemplateEvent>> slotContents = extractSlotContents(model);
     Map<String, ITemplateEvent> slots = extractSlots(fragmentModel);
-    IModel mergedModel = prepareModel(context, fragmentModel, additionalAttributes, slots, slotContents);
+    IModel mergedModel = prepareModel(context, fragmentModel, fragmentRootElementTag, additionalAttributes, slots, slotContents);
 
     model.reset();
     model.addModel(mergedModel);
@@ -90,7 +102,7 @@ private boolean isValidComponentTag(IProcessableElementTag componentElementTag)
   }
 
   private IModel loadFragmentModel(ITemplateContext context) {
-    return parseFragmentTemplateModel(context, templatePath != null ? templatePath : "pl/" + elementName + "/" + elementName);
+    return parseFragmentTemplateModel(context, templatePath);
   }
 
   private Map<String, List<ITemplateEvent>> extractSlotContents(IModel model) {
@@ -133,43 +145,96 @@ private Map<String, ITemplateEvent> extractSlots(IModel fragmentModel) {
   private IModel prepareModel(
     ITemplateContext context,
     IModel fragmentModel,
+    IProcessableElementTag fragmentRootElementTag,
     Map<String, Object> additionalAttributes,
     Map<String, ITemplateEvent> slots,
     Map<String, List<ITemplateEvent>> slotContents
   ) {
     IModelFactory modelFactory = context.getModelFactory();
     IModel newModel = modelFactory.createModel();
 
-    newModel.add(blockOpenElement(modelFactory, additionalAttributes));
+    List<ITemplateEvent> fragmentElementTags = subTreeBelow(fragmentModel, fragmentRootElementTag);
+    boolean hasPassedDownAttributes = replaceAdditionalAttributes(fragmentElementTags, modelFactory, additionalAttributes);
+    if (!hasPassedDownAttributes) {
+      newModel.add(blockOpenElement(modelFactory, additionalAttributes));
+    }
+
+    fillSlots(fragmentModel, fragmentElementTags, slots, slotContents);
 
-    List<ITemplateEvent> mergedElementTags = fillSlots(fragmentModel, slots, slotContents);
-    mergedElementTags.forEach(newModel::add);
+    fragmentElementTags.forEach(newModel::add);
 
-    newModel.add(blockCloseElement(modelFactory));
+    if (!hasPassedDownAttributes) {
+      newModel.add (blockCloseElement (modelFactory));
+    }
 
     return newModel;
   }
 
-  private List<ITemplateEvent> fillSlots(
-    IModel fragmentModel, Map<String, ITemplateEvent> slots,
+  private static Map<String,String> convertObjectMapToStringMap(Map<String, Object> objectMap) {
+    Map<String, String> stringMap = new HashMap<>(objectMap.size ());
+    objectMap.forEach((key, value) -> stringMap.put(key, value != null ? value.toString() : null));
+    return stringMap;
+  }
+
+  private boolean replaceAdditionalAttributes(List<ITemplateEvent> fragmentElementTags, IModelFactory modelFactory, Map<String, Object> additionalAttributes) {
+    boolean replaced = false;
+    Set<String> removeAttributes = Collections.singleton (dialectPrefix + ":pass-additional-attributes");
+    for (int i = 0; i < fragmentElementTags.size(); i++) {
+      ITemplateEvent templateEvent = fragmentElementTags.get(i);
+      if (templateEvent instanceof IProcessableElementTag elementTag
+          && elementTag.hasAttribute (dialectPrefix, "pass-additional-attributes")) {
+        fragmentElementTags.set(i, copyTagWithModifiedAttributes (elementTag, modelFactory, additionalAttributes, removeAttributes));
+        replaced = true;
+      }
+    }
+    return replaced;
+  }
+
+  private IProcessableElementTag copyTagWithModifiedAttributes (IProcessableElementTag elementTag, IModelFactory modelFactory, Map<String, Object> additionalAttributes, Set<String> removeAttributes) {
+    Map<String,String> newAttributes = additionalAttributes == null ? new HashMap<> () : convertObjectMapToStringMap(additionalAttributes);
+    newAttributes.putAll (elementTag.getAttributeMap ());
+    if (removeAttributes != null) {
+      removeAttributes.forEach (newAttributes::remove);
+    }
+
+    if (elementTag instanceof IOpenElementTag) {
+      return modelFactory.createOpenElementTag (
+          elementTag.getElementCompleteName (),
+          newAttributes,
+          DOUBLE,
+          false
+      );
+    } else if (elementTag instanceof IStandaloneElementTag standaloneElementTag) {
+      return modelFactory.createStandaloneElementTag (
+          elementTag.getElementCompleteName (),
+          newAttributes,
+          DOUBLE,
+          false,
+          standaloneElementTag.isMinimized ()
+      );
+    }
+    throw new IllegalArgumentException ("Unsupported tag class");
+  }
+
+  private void fillSlots(
+    IModel fragmentModel,
+    List<ITemplateEvent> fragmentElementTags,
+    Map<String, ITemplateEvent> slots,
     Map<String, List<ITemplateEvent>> slotContents
   ) {
-    List<ITemplateEvent> fragmentElementTags = subTreeBelow(fragmentModel, firstOpenElementTagWithAttribute(fragmentModel, "th:fragment"));
     slots.forEach((slotName, slotElementTag) -> {
       List<ITemplateEvent> slotContent = slotContents.get(slotName);
 
       if (slotContent == null || slotContent.isEmpty()) {
-        if (slotElementTag instanceof IOpenElementTag) {
-          slotContent = fallbackSlotContent(fragmentModel, (IOpenElementTag) slotElementTag);
+        if (slotElementTag instanceof IOpenElementTag openElementTag) {
+          slotContent = fallbackSlotContent(fragmentModel, openElementTag);
         } else {
           slotContent = emptyList();
         }
       }
 
       fillSlot(fragmentElementTags, subTreeFrom(fragmentModel, slotElementTag), slotContent);
     });
-
-    return fragmentElementTags;
   }
 
   private void fillSlot(List<ITemplateEvent> templateEvents, List<ITemplateEvent> slotSubTree, List<ITemplateEvent> slotContent) {
@@ -183,8 +248,7 @@ private static List<ITemplateEvent> fallbackSlotContent(IModel fragmentModel, IO
   }
 
   private static IOpenElementTag blockOpenElement(IModelFactory modelFactory, Map<String, Object> attributes) {
-    Map<String, String> attributesMap = new HashMap<>();
-    attributes.forEach((key, value) -> attributesMap.put(key, value != null ? value.toString() : null));
+    Map<String, String> attributesMap = convertObjectMapToStringMap (attributes);
 
     return modelFactory.createOpenElementTag("th:block", attributesMap, DOUBLE, false);
   }
@@ -194,8 +258,8 @@ private static ICloseElementTag blockCloseElement(IModelFactory modelFactory) {
   }
 
   private boolean isSlot(ITemplateEvent templateEvent) {
-    if (templateEvent instanceof IProcessableElementTag) {
-      return ((IProcessableElementTag) templateEvent).getElementCompleteName().equals(dialectPrefix + ":slot");
+    if (templateEvent instanceof IProcessableElementTag elementTag) {
+      return elementTag.getElementCompleteName().equals(dialectPrefix + ":slot");
     }
 
     return false;
@@ -212,16 +276,16 @@ private String slotNameOf(IProcessableElementTag elementTag) {
   }
 
   private static IProcessableElementTag firstOpenOrStandaloneElementTag(IModel model) {
-    return templateEventsIn(model).stream()
-      .filter((elementTag) -> elementTag instanceof IProcessableElementTag)
+    return templateEventsIn(model)
+      .filter(elementTag -> elementTag instanceof IProcessableElementTag)
       .map(templateEvent -> (IProcessableElementTag)templateEvent)
       .findFirst()
       .orElse(null);
   }
 
   private static IProcessableElementTag firstOpenElementTagWithAttribute(IModel model, String attributeName) {
-    return templateEventsIn(model).stream()
-      .filter((elementTag) -> elementTag instanceof IOpenElementTag)
+    return templateEventsIn(model)
+      .filter(elementTag -> elementTag instanceof IOpenElementTag)
       .map(templateEvent -> (IProcessableElementTag)templateEvent)
       .filter(elementTag -> elementTag.hasAttribute(attributeName))
       .findFirst()
@@ -263,10 +327,14 @@ private Map<String, Object> resolveAdditionalAttributes(IProcessableElementTag e
 
   private static Object tryResolveAttributeValue(IAttribute attribute, ITemplateContext context,
     IStandardExpressionParser expressionParser) {
+    String value = attribute.getValue();
+    if (value == null) {
+      return null;
+    }
     try {
-      return expressionParser.parseExpression(context, attribute.getValue()).execute(context);
+      return expressionParser.parseExpression(context, value).execute(context);
     } catch (TemplateProcessingException e) {
-      return attribute.getValue();
+      return value;
     }
   }
 
@@ -319,13 +387,7 @@ static List<ITemplateEvent> subTreeFrom(IModel model, ITemplateEvent startTempla
     return subTree;
   }
 
-  private static List<ITemplateEvent> templateEventsIn(IModel model) {
-    List<ITemplateEvent> templateEvents = new ArrayList<>();
-
-    for (int i = 0; i < model.size(); i++) {
-      templateEvents.add(model.get(i));
-    }
-
-    return templateEvents;
+  private static Stream<ITemplateEvent> templateEventsIn(IModel model) {
+    return IntStream.range(0, model.size()).mapToObj (model::get);
   }
 }
diff --git a/src/test/java/ch/cstettler/thymeleaf/ComponentModelProcessorTest.java b/src/test/java/ch/cstettler/thymeleaf/ComponentModelProcessorTest.java
@@ -80,6 +80,14 @@ void simple_additionalDynamicAttribute_rendersAttribute() {
     assertMarkupEquals("<i key='value'>simple</i>", html);
   }
 
+  @Test
+  void withPassAdditionalAttributes_additionalDynamicAttribute_rendersAttribute() {
+    String html = render("<pl:with-pass-additional-attributes th:attr='key=value' />");
+
+    assertMarkupEquals("<i key=\"value\">has-additional-attributes</i>" +
+                       "<b key=\"value\">also-has-additional-attributes</b>", html);
+  }
+
   @Test
   void simple_ifConditionTrue_renders() {
     String html = render("<pl:simple th:if='true' />");
@@ -119,6 +127,57 @@ void withParameter_parameterNotDefined_renders() {
     assertMarkupEquals("<i></i>", html);
   }
 
+  @Test
+  void withVariable_variableDefinedAsParameter_rendersVariable() {
+    String html = render("<pl:with-variable pl:variable='|with-variable-defined:${variable}|' />");
+
+    assertMarkupEquals("<i>with-variable-defined:null</i>", html);
+  }
+
+  @Test
+  void withVariable_variableDefinedAsByWith_rendersVariable() {
+    String html = render("<pl:with-variable th:with='variable=|with-variable-defined:${variable}|' />");
+
+    assertMarkupEquals("<i>with-variable-defined:null</i>", html);
+  }
+
+  @Test
+  void withVariable_variableNotDefined_renders() {
+    String html = render("<pl:with-variable />");
+
+    assertMarkupEquals("<i></i>", html);
+  }
+
+
+  @Test
+  void withDefaultValue_variableDefinedAsParameter_rendersProvidedVariable() {
+    String html = render("<pl:with-default-value pl:variable='|with-variable-defined:${variable}|' />");
+
+    assertMarkupEquals("<i>with-variable-defined:null</i>", html);
+  }
+
+
+  @Test
+  void withDefaultValue_variableDefinedAsByWithOnParentTag_defaultValue() {
+    String html = render("<th:block th:with='variable=|with-variable-defined:${variable}|'><pl:with-default-value /></th:block>");
+
+    assertMarkupEquals("<i>default-value</i>", html);
+  }
+
+  @Test
+  void withDefaultValue_variableDefinedAsByWithOnSameTag_rendersProvidedVariableWithDefaultValuePredefined() {
+    String html = render("<pl:with-default-value th:with='variable=|with-variable-defined:${variable}|' />");
+
+    assertMarkupEquals("<i>with-variable-defined:default-value</i>", html);
+  }
+
+  @Test
+  void withDefaultValue_variableNotDefined_rendersDefaultValue() {
+    String html = render("<pl:with-default-value />");
+
+    assertMarkupEquals("<i>default-value</i>", html);
+  }
+
   @Test
   void withDefaultSlot_slotContentDefined_rendersSlotContent() {
     String html = render(""
@@ -398,6 +457,9 @@ private static String render(String template) {
     ComponentDialect componentDialect = new ComponentDialect()
         .addComponent("simple", "components/simple.html")
         .addComponent("with-parameter", "components/with-parameter.html")
+        .addComponent("with-variable", "components/with-variable.html")
+        .addComponent("with-pass-additional-attributes", "components/with-pass-additional-attributes.html")
+        .addComponent("with-default-value", "components/with-default-value.html")
         .addComponent("with-default-and-named-slots", "components/with-default-and-named-slots.html")
         .addComponent("with-default-slot", "components/with-default-slot.html")
         .addComponent("with-named-slots", "components/with-named-slots.html")
@@ -448,4 +510,4 @@ public TemplateResolution resolveTemplate(
           .orElseThrow(() -> new IllegalStateException("no template resolver found for template '" + template + "'"));
     }
   }
-}
+}
diff --git a/src/test/resources/components/with-default-value.html b/src/test/resources/components/with-default-value.html
@@ -0,0 +1,3 @@
+<th:block xmlns:th="http://www.thymeleaf.org" th:fragment="with-variable()" pl:variable="default-value">
+  <i th:text="${variable}"></i>
+</th:block>
diff --git a/src/test/resources/components/with-pass-additional-attributes.html b/src/test/resources/components/with-pass-additional-attributes.html
diff --git a/src/test/resources/components/with-variable.html b/src/test/resources/components/with-variable.html

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+<th:block xmlns:th="http://www.thymeleaf.org" th:fragment="with-variable()" pl:variable="default-value">`
	`2`	`+ <i th:text="${variable}"></i>`
	`3`	`+</th:block>`