Fixed #357 - Added support for a 'this' expression in entity views

CHANGELOG.md

@@ -20,6 +20,7 @@ Not yet released
 * Support fetches for entity mappings in entity views
 * Automatic rewrites of id expressions in equality predicates to avoid joins
 * Various performance improvements
+* Support referring to `this` in all mapping types for putting values in embedded objects
 
 ### Bug fixes
 

core/parser/src/main/antlr4/imports/JPQL_lexer.g4

@@ -147,7 +147,7 @@ Date_literal : '{' 'd' (' ' | '\t')+ '\'' Date_string '\'' (' ' | '\t')* '}';
 
 Time_literal : '{' 't' (' ' | '\t')+ '\'' Time_string '\'' (' ' | '\t')* '}';
 
-Timestamp_literal : '{' 'ts' (' ' | '\t')+ '\'' Date_string ' ' Time_string Nanos_string '\'' (' ' | '\t')* '}';
+Timestamp_literal : '{' 'ts' (' ' | '\t')+ '\'' Date_string ' ' Time_string ('.' DIGIT*)? '\'' (' ' | '\t')* '}';
 
 Boolean_literal
      : [Tt][Rr][Uu][Ee]
@@ -211,8 +211,6 @@ fragment Date_string : DIGIT DIGIT DIGIT DIGIT '-' DIGIT DIGIT '-' DIGIT DIGIT;
 
 fragment Time_string : DIGIT DIGIT? ':' DIGIT DIGIT ':' DIGIT DIGIT;
 
-fragment Nanos_string : ('.' DIGIT*)?;
-
 fragment DIGIT: '0'..'9';
 fragment DIGIT_NOT_ZERO: '1'..'9';
 fragment ZERO: '0';

core/parser/src/main/java/com/blazebit/persistence/impl/PrefixingAndAliasReplacementQueryGenerator.java

@@ -33,16 +33,14 @@ public class PrefixingAndAliasReplacementQueryGenerator extends SimpleQueryGener
     private final String substitute;
     private final String alias;
     private final String aliasToSkip;
+    private final boolean skipPrefix;
 
-    public PrefixingAndAliasReplacementQueryGenerator(String prefix, String substitute, String alias) {
-        this(prefix, substitute, alias, null);
-    }
-
-    public PrefixingAndAliasReplacementQueryGenerator(String prefix, String substitute, String alias, String aliasToSkip) {
+    public PrefixingAndAliasReplacementQueryGenerator(String prefix, String substitute, String alias, String aliasToSkip, boolean skipPrefix) {
         this.prefix = prefix;
         this.substitute = substitute;
         this.alias = alias;
         this.aliasToSkip = aliasToSkip;
+        this.skipPrefix = skipPrefix;
     }
 
     @Override
@@ -53,10 +51,15 @@ public void visit(PathExpression expression) {
         if (size == 1) {
             PathElementExpression elementExpression = expressions.get(0);
             if (elementExpression instanceof PropertyExpression) {
-                if (alias.equals(((PropertyExpression) elementExpression).getProperty())) {
+                String property = ((PropertyExpression) elementExpression).getProperty();
+                if (alias.equals(property)) {
                     sb.append(substitute);
                     return;
                 }
+                if (skipPrefix && prefix.equals(property)) {
+                    super.visit(expression);
+                    return;
+                }
             }
         } else if (aliasToSkip != null) {
             PathElementExpression elementExpression = expressions.get(0);
@@ -68,6 +71,7 @@ public void visit(PathExpression expression) {
             }
         }
         sb.append(prefix);
+        sb.append('.');
         super.visit(expression);
     }
 

core/parser/src/main/java/com/blazebit/persistence/impl/expression/ExpressionModifierCollectingResultVisitorAdapter.java

@@ -62,6 +62,10 @@
 import java.util.List;
 
 /**
+ * This is a visitor that can be used to collect expression modifier references into an expression.
+ * When a visit method returns {@linkplain Boolean#TRUE}, an expression modifier for the expression is generated
+ * and the {@link #onModifier(ExpressionModifier)} method is called. The modifier is bound to the embedding expression
+ * i.e. the parent expression and can be used for reading or replacing the expression.
  *
  * @author Moritz Becker
  * @author Christian Beikov

core/parser/src/main/java/com/blazebit/persistence/impl/expression/InplaceModificationResultVisitorAdapter.java

@@ -36,6 +36,9 @@
 import java.util.List;
 
 /**
+ * This is a visitor that can be used to do inplace changes to an expression.
+ * This is quite similar to {@link ExpressionModifierCollectingResultVisitorAdapter},
+ * but more targeted for multiple possibly nested replacements.
  *
  * @author Moritz Becker
  * @author Christian Beikov

documentation/src/main/asciidoc/entity-view/manual/en_US/04_mappings.adoc

@@ -873,6 +873,56 @@ There is also the possibility to specify a <<anchor-fetch-strategies,_fetch stra
 {projectname} entity views generally supports the full set of link:{core_doc}#expressions[expressions] that JPQL and {projectname} core module supports,
 but in addition to that, also offers some expression extensions.
 
+==== THIS
+
+Similar to the `this` expression in Java, in a mapping expression within entity views the `this` expression can be used to refer to the entity type backing the entity view.
+The expression can be used to implement embedded objects that are able to refer to the entity type of the entity view.
+
+[source,java]
+----
+@EntityView(Cat.class)
+interface EmbeddedCatView {
+
+    @IdMapping("id")
+    Long getId();
+
+    String getName();
+}
+
+@EmbeddableEntityView(Cat.class)
+interface ExternalInterfaceView {
+
+    @Mapping("name")
+    String getExternalName();
+}
+
+@EntityView(Cat.class)
+interface CatView {
+
+    @IdMapping("id")
+    Long getId();
+
+    @Mapping("this")
+    EmbeddedCatView getEmbedded();
+
+    @Mapping("this")
+    ExternalInterfaceView getAdapter();
+}
+----
+
+Both `EmbeddedCatView` and `ExternalInterfaceView` refer to the same `Cat` as their parent `CatView`.
+The query looks as if the types were directly embedded into the entity view.
+
+[source,sql]
+----
+SELECT
+    cat.id,
+    cat.id,
+    cat.name,
+    cat.name
+FROM Cat cat
+----
+
 ==== OUTER
 
 In {projectname} core the `OUTER` function can be used to refer to the query root of a parent query from within a subquery.
@@ -1009,9 +1059,6 @@ TIP: Make sure you understand the <<anchor-select-fetch-strategy-view-root,impli
 // ==== QUERY_ROOT
 // TODO: add a macro for referencing the query root
 
-// ==== THIS
-// TODO: add a macro for referencing "this"
-
 [[anchor-constructor-mapping]]
 === Entity View constructor mapping
 

entity-view/impl/pom.xml

@@ -66,6 +66,12 @@
             <artifactId>javaee-api</artifactId>
             <scope>provided</scope>
         </dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

entity-view/impl/src/main/java/com/blazebit/persistence/view/impl/CorrelationProviderProxyBase.java

@@ -22,6 +22,7 @@
 import com.blazebit.persistence.impl.expression.MacroFunction;
 import com.blazebit.persistence.view.CorrelationBuilder;
 import com.blazebit.persistence.view.CorrelationProvider;
+import com.blazebit.persistence.view.impl.metamodel.AbstractAttribute;
 import com.blazebit.persistence.view.spi.ViewRootJpqlMacro;
 
 /**
@@ -53,18 +54,19 @@ private CorrelationProviderProxyBase(Class<?> correlated, String correlationKeyA
     @Override
     public void applyCorrelation(CorrelationBuilder correlationBuilder, String correlationExpression) {
         String alias = correlationBuilder.getCorrelationAlias();
-        String prefix = alias + ".";
 
         // Find out the view root alias
         ExpressionFactory expressionFactory = correlationBuilder.getService(ExpressionFactory.class);
         MacroFunction viewRootFunction = expressionFactory.getDefaultMacroConfiguration().get("VIEW_ROOT");
         ViewRootJpqlMacro viewRootMacro = (ViewRootJpqlMacro) viewRootFunction.getState()[0];
 
         // Prefix all paths except view root alias based ones and substitute the key alias with the correlation expression
-        PrefixingAndAliasReplacementQueryGenerator generator = new PrefixingAndAliasReplacementQueryGenerator(prefix, correlationExpression, correlationKeyAlias, viewRootMacro.getViewRoot());
+        String viewRoot = viewRootMacro.getViewRoot();
+        PrefixingAndAliasReplacementQueryGenerator generator = new PrefixingAndAliasReplacementQueryGenerator(alias, correlationExpression, correlationKeyAlias, viewRoot, true);
         StringBuilder buffer = new StringBuilder(approximateExpressionSize);
         generator.setQueryBuffer(buffer);
-        Expression expression = expressionFactory.createBooleanExpression(this.correlationExpression, false);
+        String expressionString = AbstractAttribute.replaceThisFromMapping(this.correlationExpression, alias);
+        Expression expression = expressionFactory.createBooleanExpression(expressionString, false);
         expression.accept(generator);
 
         correlationBuilder.correlate(correlated)

entity-view/impl/src/main/java/com/blazebit/persistence/view/impl/EntityViewManagerImpl.java

@@ -97,7 +97,8 @@ public EntityViewManagerImpl(EntityViewConfigurationImpl config, CriteriaBuilder
         Set<Class<?>> entityViews = config.getEntityViews();
 
         Set<String> errors = new HashSet<String>();
-        MetamodelBuildingContext context = new MetamodelBuildingContextImpl(cbf.getService(EntityMetamodel.class), cbf.getService(ExpressionFactory.class), proxyFactory, entityViews, errors);
+        ExpressionFactory expressionFactory = cbf.getService(ExpressionFactory.class);
+        MetamodelBuildingContext context = new MetamodelBuildingContextImpl(cbf.getService(EntityMetamodel.class), expressionFactory, proxyFactory, entityViews, errors);
         this.metamodel = new ViewMetamodelImpl(entityViews, cbf, context, validateExpressions);
 
         if (!errors.isEmpty()) {
@@ -125,11 +126,11 @@ public EntityViewManagerImpl(EntityViewConfigurationImpl config, CriteriaBuilder
             for (ViewType<?> view : metamodel.getViews()) {
                 // TODO: Might be a good idea to let the view root be overridden or specified via the annotation
                 String probableViewRoot = StringUtils.firstToLower(view.getEntityClass().getSimpleName());
-                ExpressionFactory expressionFactory = context.createMacroAwareExpressionFactory(probableViewRoot);
-                getTemplate(expressionFactory, view, null, null);
+                ExpressionFactory macroAwareExpressionFactory = context.createMacroAwareExpressionFactory(probableViewRoot);
+                getTemplate(macroAwareExpressionFactory, view, null, null);
 
                 for (MappingConstructor<?> constructor : view.getConstructors()) {
-                    getTemplate(expressionFactory, view, (MappingConstructor) constructor, null);
+                    getTemplate(macroAwareExpressionFactory, view, (MappingConstructor) constructor, null);
                 }
             }
         } else if (Boolean.valueOf(String.valueOf(properties.get(ConfigurationProperties.PROXY_EAGER_LOADING)))) {
@@ -269,23 +270,29 @@ private <T> Constructor<T> findConstructor(Constructor<T>[] constructors, Class<
     }
 
     @SuppressWarnings("unchecked")
-    public void applyObjectBuilder(Class<?> clazz, String mappingConstructorName, String entityViewRoot, EntityViewConfiguration configuration) {
+    public String applyObjectBuilder(Class<?> clazz, String mappingConstructorName, String entityViewRoot, EntityViewConfiguration configuration) {
         ViewType<?> viewType = getMetamodel().view(clazz);
         if (viewType == null) {
             throw new IllegalArgumentException("There is no entity view for the class '" + clazz.getName() + "' registered!");
         }
         MappingConstructor<?> mappingConstructor = viewType.getConstructor(mappingConstructorName);
-        applyObjectBuilder(viewType, mappingConstructor, viewType.getName(), entityViewRoot, configuration.getCriteriaBuilder(), configuration, 0, true);
+        return applyObjectBuilder(viewType, mappingConstructor, viewType.getName(), entityViewRoot, configuration.getCriteriaBuilder(), configuration, 0, true);
     }
 
-    public void applyObjectBuilder(ViewType<?> viewType, MappingConstructor<?> mappingConstructor, String viewName, String entityViewRoot, FullQueryBuilder<?, ?> criteriaBuilder, EntityViewConfiguration configuration, int offset, boolean registerMacro) {
-        criteriaBuilder.selectNew(createObjectBuilder(viewType, mappingConstructor, viewName, entityViewRoot, criteriaBuilder, configuration, offset, registerMacro));
+    public String applyObjectBuilder(ViewType<?> viewType, MappingConstructor<?> mappingConstructor, String viewName, String entityViewRoot, FullQueryBuilder<?, ?> criteriaBuilder, EntityViewConfiguration configuration, int offset, boolean registerMacro) {
+        From root = getFromByViewRoot(criteriaBuilder, entityViewRoot);
+        criteriaBuilder.selectNew(createObjectBuilder(viewType, mappingConstructor, viewName, root, criteriaBuilder, configuration, offset, registerMacro));
+        return root.getAlias();
     }
 
     public ObjectBuilder<?> createObjectBuilder(ViewType<?> viewType, MappingConstructor<?> mappingConstructor, String viewName, String entityViewRoot, FullQueryBuilder<?, ?> criteriaBuilder, EntityViewConfiguration configuration, int offset, boolean registerMacro) {
         From root = getFromByViewRoot(criteriaBuilder, entityViewRoot);
+        return createObjectBuilder(viewType, mappingConstructor, viewName, root, criteriaBuilder, configuration, offset, registerMacro);
+    }
+
+    public ObjectBuilder<?> createObjectBuilder(ViewType<?> viewType, MappingConstructor<?> mappingConstructor, String viewName, From root, FullQueryBuilder<?, ?> criteriaBuilder, EntityViewConfiguration configuration, int offset, boolean registerMacro) {
         Class<?> entityClazz = root.getType();
-        entityViewRoot = root.getAlias();
+        String entityViewRoot = root.getAlias();
         ExpressionFactory ef = criteriaBuilder.getService(ExpressionFactory.class);
         if (!viewType.getEntityClass().isAssignableFrom(entityClazz)) {
             throw new IllegalArgumentException("The given view type with the entity type '" + viewType.getEntityClass().getName()