Hibernate Learning - EntityGraph Example Added

NRuslanR · Sep 27, 2022 · f10ac70 · f10ac70
1 parent d711152
commit f10ac70
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Showing 4 changed files with 90 additions and 2 deletions.
diff --git a/.vscode/launch.json b/.vscode/launch.json
@@ -5,7 +5,7 @@
             "name": "Launch HibernateLearning",
             "request": "launch",
             "mainClass": "com.learning.hibernate.HibernateLearning",
-            "args": "FetchMode",
+            "args": "EntityGraph",
             "projectName": "hibernate"
         },
         {

diff --git a/Learning/Hibernate/hibernate/src/main/java/com/learning/hibernate/entities/ShoppingCart.java b/Learning/Hibernate/hibernate/src/main/java/com/learning/hibernate/entities/ShoppingCart.java
@@ -8,6 +8,8 @@
 import jakarta.persistence.CascadeType;
 import jakarta.persistence.Entity;
 import jakarta.persistence.JoinColumn;
+import jakarta.persistence.NamedAttributeNode;
+import jakarta.persistence.NamedEntityGraph;
 import jakarta.persistence.OneToMany;
 import jakarta.persistence.SequenceGenerator;
 import jakarta.persistence.Table;
@@ -25,6 +27,10 @@
 @Table(name = "shopping_carts")
 @ToString(callSuper = true)
 @SequenceGenerator(name = "pk_gen", sequenceName = "sc_pk_gen", initialValue = 100)
+@NamedEntityGraph(
+    name = "shopping-cart-graph", 
+    attributeNodes = @NamedAttributeNode(value = "items")
+)
 public class ShoppingCart extends SequencedExampleEntity {
 
     @NonNull

diff --git a/...Hibernate/hibernate/src/main/java/com/learning/hibernate/examples/EntityGraphExample.java b/...Hibernate/hibernate/src/main/java/com/learning/hibernate/examples/EntityGraphExample.java
@@ -0,0 +1,80 @@
+package com.learning.hibernate.examples;
+
+import java.util.Collection;
+import java.util.stream.IntStream;
+
+import org.hibernate.Session;
+import org.hibernate.stat.internal.SessionStatisticsImpl;
+
+import com.learning.hibernate.entities.ShoppingCart;
+import com.learning.hibernate.entities.ShoppingCartItem;
+import com.learning.hibernate.utils.HibernateUtils;
+import com.learning.hibernate.values.Money;
+
+import jakarta.persistence.EntityGraph;
+
+public class EntityGraphExample extends HibernateExample {
+
+    public EntityGraphExample() {
+        super("EntityGraph");
+    }
+
+    @Override
+    protected void doRun(Session session, Object data) throws Exception {
+
+        prepareData(session);
+        runEntityGraphExample(session);
+
+    }
+
+    private void prepareData(Session session) {
+
+        final int itemCount = 5, childItemCount = 5;
+
+        Collection<ShoppingCart> cartsToBePrepared =
+            IntStream
+                .rangeClosed(1, itemCount)
+                .boxed()
+                .map(i -> 
+                    new ShoppingCart(
+                        "Cart" + i, 
+                        IntStream
+                            .rangeClosed(1, childItemCount)
+                            .boxed()
+                            .map(j -> 
+                                ShoppingCartItem.of(
+                                    23, "Product" + j, Money.ofUSD(43
+                                ))
+                            ).toList()
+                    )
+                        ).toList();
+
+        HibernateUtils.persistInTransaction(session, cartsToBePrepared);
+    }
+
+    private void runEntityGraphExample(Session session) {
+
+        EntityGraph rootGraph = session.getEntityGraph("shopping-cart-graph");
+
+        Collection<ShoppingCart> carts = 
+            session
+                .createQuery(
+        "select sc from ShoppingCart sc",
+                ShoppingCart.class
+                )
+                .setHint("jakarta.persistence.loadgraph", rootGraph)
+                .getResultList();
+
+        printEntities(carts, "carts fetched by entity load-based graph");
+
+        carts =
+            session
+                .createQuery(
+                    "select sc from ShoppingCart sc", ShoppingCart.class
+                ).setHint("jakarta.persistence.fetchgraph", rootGraph
+                        ).getResultList();
+
+        printEntities(carts, "carts fetched by entity fetch-based graph");
+    }
+
+}
diff --git a/...ibernate/hibernate/src/main/java/com/learning/hibernate/utils/HibernateExamplesUtils.java b/...ibernate/hibernate/src/main/java/com/learning/hibernate/utils/HibernateExamplesUtils.java
@@ -13,6 +13,7 @@
 import com.learning.hibernate.examples.AttributeConvertersExample;
 import com.learning.hibernate.examples.BatchOperationsExample;
 import com.learning.hibernate.examples.CriteriaAPIExample;
+import com.learning.hibernate.examples.EntityGraphExample;
 import com.learning.hibernate.examples.EntityIdentifyingStrategiesExample;
 import com.learning.hibernate.examples.EntityLifeCycleEventsExample;
 import com.learning.hibernate.examples.EntityLifeCycleExample;
@@ -47,7 +48,8 @@ public static Examples getExamples() throws Exception
                     new SortingAndPaginationExample(),
                     new BatchOperationsExample(),
                     new CriteriaAPIExample(),
-                    new FetchModeExample()
+                    new FetchModeExample(),
+                    new EntityGraphExample()
                 );
 
         return examples;