Optionally enforce required elements in XSDs

modello-core/src/main/java/org/codehaus/modello/ModelloParameterConstants.java

@@ -71,6 +71,13 @@ public class ModelloParameterConstants
      */
     public static final String EXTENDED_CLASSNAME_SUFFIX = "modello.xpp3.extended.suffix";
 
+    /**
+     * Boolean flag enforcing existence of mandatory elements in the XSD.
+     * If set to {@code false} will not require mandatory elements in the XML which can be useful if the XML is post processed (e.g. POM merging with parents)
+     * where mandatory elements might be contributed by sources outside the XML.
+     * @since 2.1
+     */
+    public static final String XSD_ENFORCE_MANDATORY_ELEMENTS = "modello.xsd.enforce.mandatory.element";
     private ModelloParameterConstants()
     {
     }

modello-maven-plugin/src/main/java/org/codehaus/modello/maven/ModelloXsdMojo.java

@@ -45,6 +45,15 @@ public class ModelloXsdMojo
     @Parameter( defaultValue = "${project.build.directory}/generated-site/resources/xsd", required = true )
     private File outputDirectory;
 
+    /**
+     * Boolean flag to enforce mandatory elements in the XML schema.
+     * If set to {@code false} the XSD won't enforce mandatory elements in the XML which can be useful if the XML is post processed (e.g. POM merging with parents).
+     * The default value is {@code false} for backwards compatibility reasons, but should be set to {@code true} for most cases.
+     * @since 2.1.0
+     */
+    @Parameter( defaultValue = "false")
+    private boolean enforceMandatoryElements;
+
     /**
      *
      * @since 1.0-alpha-21
@@ -65,6 +74,7 @@ protected void customizeParameters( Properties parameters )
         {
             parameters.put( ModelloParameterConstants.OUTPUT_XSD_FILE_NAME, xsdFileName );
         }
+        parameters.put( ModelloParameterConstants.XSD_ENFORCE_MANDATORY_ELEMENTS, enforceMandatoryElements );
     }
 
     protected boolean producesCompilableResult()

modello-plugins/modello-plugin-xsd/src/main/java/org/codehaus/modello/plugin/xsd/XsdGenerator.java

@@ -87,6 +87,7 @@ private void generateXsd( Properties parameters )
 
         // we assume parameters not null
         String xsdFileName = parameters.getProperty( ModelloParameterConstants.OUTPUT_XSD_FILE_NAME );
+        boolean enforceMandatoryElements = Boolean.parseBoolean( parameters.getProperty( ModelloParameterConstants.XSD_ENFORCE_MANDATORY_ELEMENTS ) );
 
         File f = new File( directory, objectModel.getId() + "-" + getGeneratedVersion() + ".xsd" );
 
@@ -137,7 +138,8 @@ private void generateXsd( Properties parameters )
             // Element descriptors
             // Traverse from root so "abstract" models aren't included
             int initialCapacity = objectModel.getClasses( getGeneratedVersion() ).size();
-            writeComplexTypeDescriptor( w, objectModel, root, new HashSet<ModelClass>( initialCapacity ) );
+            writeComplexTypeDescriptor( w, objectModel, root, new HashSet<ModelClass>( initialCapacity ),
+                    enforceMandatoryElements );
 
             w.endElement();
         }
@@ -184,7 +186,7 @@ private static void writeDocumentation( XMLWriter w, String version, String desc
     }
 
     private void writeComplexTypeDescriptor( XMLWriter w, Model objectModel, ModelClass modelClass,
-                                             Set<ModelClass> written )
+                                             Set<ModelClass> written, boolean enforceMandatoryElements )
     {
         written.add( modelClass );
 
@@ -242,9 +244,12 @@ private void writeComplexTypeDescriptor( XMLWriter w, Model objectModel, ModelCl
                 {
                     w.startElement( "xs:element" );
 
-                    // Usually, would only do this if the field is not "required", but due to inheritance, it may be
-                    // present, even if not here, so we need to let it slide
-                    w.addAttribute( "minOccurs", "0" );
+                    if ( !enforceMandatoryElements || !field.isRequired() )
+                    {
+                        // Usually, would only do this if the field is not "required", but due to inheritance, it may be
+                        // present, even if not here, so we need to let it slide
+                        w.addAttribute( "minOccurs", "0" );
+                    }
                 }
 
                 String xsdType = getXsdType( field.getType() );
@@ -428,7 +433,7 @@ else if ( xsdType == null )
         {
             if ( !written.contains( fieldModelClass ) )
             {
-                writeComplexTypeDescriptor( w, objectModel, fieldModelClass, written );
+                writeComplexTypeDescriptor( w, objectModel, fieldModelClass, written, enforceMandatoryElements );
             }
         }
     }

modello-plugins/modello-plugin-xsd/src/test/java/org/codehaus/modello/plugin/xsd/FeaturesXsdGeneratorTest.java

@@ -24,6 +24,7 @@
 
 import org.codehaus.modello.AbstractModelloGeneratorTest;
 import org.codehaus.modello.ModelloException;
+import org.codehaus.modello.ModelloParameterConstants;
 import org.codehaus.modello.core.ModelloCore;
 import org.codehaus.modello.model.Model;
 import org.xml.sax.SAXParseException;
@@ -56,7 +57,8 @@ public void testXsdGenerator()
         Model model = modello.loadModel( getXmlResourceReader( "/features.mdo" ) );
 
         Properties parameters = getModelloParameters( "1.0.0" );
-
+        parameters.setProperty( ModelloParameterConstants.XSD_ENFORCE_MANDATORY_ELEMENTS, "true" );
+
         modello.generate( model, "xsd", parameters );
 
         SchemaFactory sf = SchemaFactory.newInstance( XMLConstants.W3C_XML_SCHEMA_NS_URI );
@@ -80,7 +82,19 @@ public void testXsdGenerator()
         catch ( SAXParseException e )
         {
             // ok, expected exception
-            assertTrue( String.valueOf( e.getMessage() ).contains( "invalidElement" ) );
+            assertTrue( e.getMessage().contains( "invalidElement" ) );
+        }
+
+        try
+        {
+            validator.validate( new StreamSource( getClass().getResourceAsStream( "/features-missing-required.xml" ) ) );
+            fail( "parsing of features-invalid.xml should have failed" );
+        }
+        catch ( SAXParseException e )
+        {
+            // ok, expected exception
+            assertTrue( e.getMessage().contains( "description" ) );
+            assertTrue( e.getMessage().endsWith(" is expected."));
         }
 
         try
@@ -91,7 +105,7 @@ public void testXsdGenerator()
         catch ( SAXParseException e )
         {
             // ok, expected exception
-            assertTrue( String.valueOf( e.getMessage() ).contains( "transientString" ) );
+            assertTrue( e.getMessage().contains( "transientString" ) );
         }
     }
 }

modello-plugins/modello-plugin-xsd/src/test/java/org/codehaus/modello/plugin/xsd/ModelloXsdGeneratorTest.java

@@ -23,6 +23,7 @@
  */
 
 import org.codehaus.modello.AbstractModelloGeneratorTest;
+import org.codehaus.modello.ModelloParameterConstants;
 import org.codehaus.modello.core.ModelloCore;
 import org.codehaus.modello.model.Model;
 import org.xml.sax.SAXException;

modello-plugins/modello-plugin-xsd/src/test/resources/features-missing-required.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0"?>
+
+<features-demo xmlns="http://codehaus-plexus.github.io/FEATURES/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+   xsi:schemaLocation="http://codehaus-plexus.github.io/FEATURES/1.0.0 http://codehaus-plexus.github.io/features-1.0.0.xsd">
+</features-demo>

modello-test/src/main/resources/features.xml

@@ -3,7 +3,7 @@
 <features-demo xmlns="http://codehaus-plexus.github.io/FEATURES/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://codehaus-plexus.github.io/FEATURES/1.0.0 http://codehaus-plexus.github.io/features-1.0.0.xsd">
   <versionField>1.0.0</versionField>
-  <!--required></required--><!-- TODO: this field is marked required but not set in the XML, should fail... -->
+  <required></required>
   <identifier>id</identifier>
   <identifierPart2><id>reference</id></identifierPart2>