Merge pull request #495 from codeconsole/6.2.x-optional-templates

Allow optional attribute for g.render that will ignore if tag if template does not exist.

grails-web-gsp-taglib/src/main/groovy/org/grails/plugins/web/taglib/RenderTagLib.groovy

@@ -47,6 +47,7 @@ class RenderTagLib implements TagLibrary {
      * &lt;g:render template="atemplate" bean="${user}" /&gt;<br/>
      *
      * @attr template REQUIRED The name of the template to apply
+     * @attr optional if true, this tag will be ignored when the template does not exist.
      * @attr contextPath the context path to use (relative to the application context path). Defaults to "" or path to the plugin for a plugin view or template.
      * @attr bean The bean to apply the template against
      * @attr model The model to apply the template against as a java.util.Map

grails-web-gsp/src/main/groovy/org/grails/web/gsp/GroovyPagesTemplateRenderer.java

@@ -115,6 +115,9 @@ public void render(GrailsWebRequest webRequest, TemplateVariableBinding pageScop
         final Object controller = webRequest.getAttribute(GrailsApplicationAttributes.CONTROLLER, GrailsWebRequest.SCOPE_REQUEST);
         Template t = findAndCacheTemplate(controller, pageScope, templateName, contextPath, pluginName, uri);
         if (t == null) {
+            if (getBooleanValue(attrs, "optional")) {
+                return; // allow missing templates if optional == "true"
+            }
             throw new GrailsTagException("Template not found for name [" + templateName + "] and path [" + uri + "]");
         }
 
@@ -289,6 +292,12 @@ private String getStringValue(Map<String, Object> attrs, String key) {
         return String.valueOf(val);
     }
 
+    private boolean getBooleanValue(Map<String, Object> attrs, String key) {
+        String val = getStringValue(attrs, key);
+        if (val.isBlank()) return false;
+        return Boolean.parseBoolean(val);
+    }
+
     public void setGroovyPageLocator(GrailsConventionGroovyPageLocator locator) {
         groovyPageLocator = locator;
     }