Enhancement#425 entity graph fetch

jopa-api/src/main/java/cz/cvut/kbss/jopa/model/AttributeNode.java

@@ -0,0 +1,25 @@
+package cz.cvut.kbss.jopa.model;
+
+import java.util.Map;
+
+/**
+ * Represents an attribute node of an entity graph.
+ *
+ * @param <T> The type of the attribute
+ */
+public interface AttributeNode<T> {
+
+    /**
+     * Gets the name of the attribute corresponding to the attribute node.
+     *
+     * @return name of the attribute
+     */
+    String getAttributeName();
+
+    /**
+     * Return the map of subgraphs associated with this attribute node.
+     *
+     * @return Map of subgraphs associated with this attribute node or empty Map if none have been defined
+     */
+    Map<Class, Subgraph> getSubgraphs();
+}

jopa-api/src/main/java/cz/cvut/kbss/jopa/model/EntityGraph.java

@@ -0,0 +1,108 @@
+package cz.cvut.kbss.jopa.model;
+
+import cz.cvut.kbss.jopa.model.metamodel.Attribute;
+
+import java.util.List;
+
+/**
+ * This type represents the root of an entity graph that will be used as a template to define the attribute nodes and
+ * boundaries of a graph of entities and entity relationships.
+ * <p>
+ * The root must be an entity type.
+ * <p>
+ * The methods to add subgraphs implicitly create the corresponding attribute nodes as well; such attribute nodes should
+ * not be redundantly specified.
+ *
+ * @param <T> The type of the root entity
+ */
+public interface EntityGraph<T> {
+
+    /**
+     * Adds one or more attribute nodes to the entity graph.
+     *
+     * @param attribute Attribute to add
+     * @throws IllegalStateException If this {@code EntityGraph} has been statically defined
+     */
+    void addAttributeNodes(Attribute<T, ?>... attribute);
+
+    /**
+     * Adds one or more attribute nodes to the entity graph.
+     *
+     * @param attributeName Name of the attribute to add
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute is not an attribute of this managed type
+     */
+    void addAttributeNodes(String... attributeName);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type.
+     * <p>
+     * This allows for construction of multi-node entity graphs that include related managed types.
+     *
+     * @param attribute Attribute to add
+     * @param <X>       Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<X> addSubgraph(Attribute<T, X> attribute);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type.
+     * <p>
+     * This allows for construction of multi-node entity graphs that include related managed types.
+     *
+     * @param attributeName Name of the attribute to add
+     * @param <X>           Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute is not an attribute of this managed type
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<X> addSubgraph(String attributeName);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type with inheritance.
+     * <p>
+     * This allows for multiple subclass subgraphs to be defined for this node of the entity graph. Subclass subgraphs
+     * will automatically include the specified attributes of superclass subgraphs.
+     *
+     * @param attribute Attribute to add
+     * @param cls       Entity subclass
+     * @param <X>       Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<? extends X> addSubgraph(Attribute<T, X> attribute, Class<? extends X> cls);
+
+    /**
+     * Add additional attributes to this entity graph that correspond to attributes of subclasses of this EntityGraph's
+     * entity type.
+     * <p>
+     * Subclass subgraphs will automatically include the specified attributes of superclass subgraphs.
+     *
+     * @param cls Entity subclass
+     * @return Subgraph for the subclass
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the type is not a managed type
+     */
+    Subgraph<? extends T> addSubclassSubgraph(Class<? extends T> cls);
+
+    /**
+     * Gets the attribute nodes corresponding to the attributes of this managed type that are included in the subgraph.
+     *
+     * @return List of attribute nodes included in the subgraph or empty list if none have been defined
+     */
+    List<AttributeNode<?>> getAttributeNodes();
+
+    /**
+     * Gets the name of a named EntityGraph (an entity graph defined by means of the NamedEntityGraph annotation, or
+     * added by means of the addNamedEntityGraph method).
+     * <p>
+     * Returns null if the EntityGraph is not a named EntityGraph.
+     *
+     * @return Entity graph name, {@code null} if it is not named
+     */
+    String getName();
+}

jopa-api/src/main/java/cz/cvut/kbss/jopa/model/EntityManager.java

@@ -353,6 +353,15 @@ public interface EntityManager extends AutoCloseable {
      */
     Query createNativeQuery(String sparqlString, String resultSetMapping);
 
+    /**
+     * Returns a mutable {@link EntityGraph} that can be used to dynamically create an entity graph.
+     *
+     * @param rootType Entity class
+     * @param <T>      Root entity class type
+     * @return Entity graph
+     */
+    <T> EntityGraph<T> createEntityGraph(Class<T> rootType);
+
     /**
      * Return an object of the specified type to allow access to the provider-specific API. If the provider's
      * EntityManager implementation does not support the specified class, the {@link OWLPersistenceException} is

jopa-api/src/main/java/cz/cvut/kbss/jopa/model/Subgraph.java

@@ -0,0 +1,88 @@
+package cz.cvut.kbss.jopa.model;
+
+import cz.cvut.kbss.jopa.model.metamodel.Attribute;
+
+import java.util.List;
+
+/**
+ * This type represents a subgraph for an attribute node that corresponds to a Managed Type.
+ * <p>
+ * Using this class, an entity subgraph can be embedded within an EntityGraph.
+ *
+ * @param <T> The type of the attribute
+ */
+public interface Subgraph<T> {
+
+    /**
+     * Adds one or more attribute nodes to the entity graph.
+     *
+     * @param attribute Attribute to add
+     * @throws IllegalStateException If this {@code EntityGraph} has been statically defined
+     */
+    void addAttributeNodes(Attribute<T, ?>... attribute);
+
+    /**
+     * Adds one or more attribute nodes to the entity graph.
+     *
+     * @param attributeName Name of the attribute to add
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute is not an attribute of this managed type
+     */
+    void addAttributeNodes(String... attributeName);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type.
+     * <p>
+     * This allows for construction of multi-node entity graphs that include related managed types.
+     *
+     * @param attribute Attribute to add
+     * @param <X>       Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<X> addSubgraph(Attribute<T, X> attribute);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type.
+     * <p>
+     * This allows for construction of multi-node entity graphs that include related managed types.
+     *
+     * @param attributeName Name of the attribute to add
+     * @param <X>           Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute is not an attribute of this managed type
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<X> addSubgraph(String attributeName);
+
+    /**
+     * Adds a node to the graph that corresponds to a managed type with inheritance.
+     * <p>
+     * This allows for multiple subclass subgraphs to be defined for this node of the entity graph. Subclass subgraphs
+     * will automatically include the specified attributes of superclass subgraphs.
+     *
+     * @param attribute Attribute to add
+     * @param cls       Entity subclass
+     * @param <X>       Attribute type
+     * @return Subgraph for the attribute
+     * @throws IllegalStateException    If this {@code EntityGraph} has been statically defined
+     * @throws IllegalArgumentException If the attribute's target type is not a managed type
+     */
+    <X> Subgraph<? extends X> addSubgraph(Attribute<T, X> attribute, Class<? extends X> cls);
+
+    /**
+     * Gets the attribute nodes corresponding to the attributes of this managed type that are included in the subgraph.
+     *
+     * @return List of attribute nodes included in the subgraph or empty list if none have been defined
+     */
+    List<AttributeNode<?>> getAttributeNodes();
+
+    /**
+     * Gets the type for which this subgraph was defined.
+     *
+     * @return managed type referenced by the subgraph
+     */
+    Class<T> getClassType();
+}

jopa-impl/src/main/java/cz/cvut/kbss/jopa/model/AbstractQuery.java

@@ -24,11 +24,9 @@
 import cz.cvut.kbss.jopa.model.query.Query;
 import cz.cvut.kbss.jopa.query.QueryHolder;
 import cz.cvut.kbss.jopa.sessions.ConnectionWrapper;
-import cz.cvut.kbss.jopa.utils.ThrowingConsumer;
 import cz.cvut.kbss.ontodriver.ResultSet;
 import cz.cvut.kbss.ontodriver.Statement;
 import cz.cvut.kbss.ontodriver.exception.OntoDriverException;
-import cz.cvut.kbss.ontodriver.iteration.ResultRow;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -121,7 +119,7 @@ public void executeUpdate() {
         }
     }
 
-    private Statement initQueryStatement() {
+    Statement initQueryStatement() {
         final Statement stmt = connection.createStatement();
         applyQueryHints(stmt);
         logQuery();
@@ -265,28 +263,14 @@ void checkNumericParameter(int param, String name) {
         }
     }
 
-    /**
-     * Executes the query and lets the specified consumer deal with each row in the result set.
-     *
-     * @param consumer Called for every row in the result set
-     * @throws OntoDriverException When something goes wrong during query evaluation or result set processing
-     */
-    void executeQuery(ThrowingConsumer<ResultRow, OntoDriverException> consumer) throws OntoDriverException {
-        try (final Statement stmt = initQueryStatement()) {
-            final ResultSet rs = stmt.executeQuery(query.assembleQuery());
-            for (ResultRow row : rs) {
-                consumer.accept(row);
-            }
-        }
-    }
-
     private void applyQueryHints(Statement statement) {
         hints.forEach((hint, value) -> QueryHintsHandler.apply(hint, value, this, statement));
     }
 
     <R> Stream<R> executeQueryForStream(QueryResultLoader<R> resultLoader) throws OntoDriverException {
         final Statement stmt = initQueryStatement();
         final ResultSet rs = stmt.executeQuery(query.assembleQuery());
+        resultLoader.init(rs);
         final Runnable closeHandler = () -> {
             try {
                 stmt.close();

jopa-impl/src/main/java/cz/cvut/kbss/jopa/model/AttributeNodeImpl.java

@@ -0,0 +1,40 @@
+package cz.cvut.kbss.jopa.model;
+
+import cz.cvut.kbss.jopa.model.metamodel.Attribute;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class AttributeNodeImpl<X> implements AttributeNode<X> {
+
+    private final Attribute<?, X> attribute;
+
+    private final Map<Class, Subgraph> subgraphs = new HashMap<>();
+
+    public AttributeNodeImpl(Attribute<?, X> attribute) {
+        this.attribute = attribute;
+    }
+
+    public Attribute<?, X> getAttribute() {
+        return attribute;
+    }
+
+    @Override
+    public String getAttributeName() {
+        return attribute.getName();
+    }
+
+    @Override
+    public Map<Class, Subgraph> getSubgraphs() {
+        return subgraphs;
+    }
+
+    void addSubgraph(EntityGraphImpl<?> graph) {
+        subgraphs.put(graph.getClassType(), graph);
+    }
+
+    @Override
+    public String toString() {
+        return attribute.toString();
+    }
+}