From 6d0556a120afa852f16d501c97f5706a3c74f0db Mon Sep 17 00:00:00 2001
From: rob bygrave <robin.bygrave@gmail.com>
Date: Thu, 2 Aug 2018 23:18:44 +1200
Subject: [PATCH] #1460 - ENH: Add FetchGroup ... as a mechanism to specify
 select() + fetch() separately from Query

Change to add generics for FetchGroup
---
 src/main/java/io/ebean/ExpressionList.java    |  2 +-
 src/main/java/io/ebean/FetchGroup.java        | 26 ++++++-------
 src/main/java/io/ebean/FetchGroupBuilder.java | 30 ++++++++------
 src/main/java/io/ebean/Query.java             |  2 +-
 src/main/java/io/ebean/XServiceProvider.java  |  8 ++--
 .../ebean/service/SpiFetchGroupService.java   | 11 ++++--
 .../server/query/DFetchGroup.java             |  2 +-
 .../server/query/DFetchGroupBuilder.java      | 39 +++++++++++--------
 .../server/query/DFetchGroupService.java      |  8 ++--
 .../server/querydefn/SpiFetchGroup.java       |  2 +-
 src/test/java/io/ebean/FetchGroupTest.java    | 14 ++++---
 11 files changed, 81 insertions(+), 63 deletions(-)

diff --git a/src/main/java/io/ebean/ExpressionList.java b/src/main/java/io/ebean/ExpressionList.java
index 2a2a6938b..9ce5e8d08 100644
--- a/src/main/java/io/ebean/ExpressionList.java
+++ b/src/main/java/io/ebean/ExpressionList.java
@@ -415,7 +415,7 @@ public interface ExpressionList<T> {
   /**
    * Apply the fetchGroup which defines what part of the object graph to load.
    */
-  Query<T> select(FetchGroup fetchGroup);
+  Query<T> select(FetchGroup<T> fetchGroup);
 
   /**
    * Set whether this query uses DISTINCT.
diff --git a/src/main/java/io/ebean/FetchGroup.java b/src/main/java/io/ebean/FetchGroup.java
index 54552a227..003bd0de9 100644
--- a/src/main/java/io/ebean/FetchGroup.java
+++ b/src/main/java/io/ebean/FetchGroup.java
@@ -13,7 +13,7 @@ import javax.annotation.Nonnull;
  * <h3>Select example</h3>*
  * <pre>{@code
  *
- * FetchGroup fetchGroup = FetchGroup.of("name, status");
+ * FetchGroup<Customer> fetchGroup = FetchGroup.of(Customer.class, "name, status");
  *
  * Customer.query()
  *   .select(fetchGroup)
@@ -24,7 +24,7 @@ import javax.annotation.Nonnull;
  * <h3>Select and fetch example</h3>
  * <pre>{@code
  *
- * FetchGroup fetchGroup = FetchGroup
+ * FetchGroup<Customer> fetchGroup = FetchGroup.of(Customer.class)
  *   .select("name, status")
  *   .fetch("contacts", "firstName, lastName, email")
  *   .build();
@@ -41,12 +41,12 @@ import javax.annotation.Nonnull;
  * </p>
  * <pre>{@code
  *
- *  FetchGroup FG_ADDRESS = FetchGroup
+ *  FetchGroup<Address> FG_ADDRESS = FetchGroup.of(Address.class)
  *    .select("line1, line2, city")
  *    .fetch("country", "name")
  *    .build();
  *
- *  FetchGroup FG_CUSTOMER = FetchGroup
+ *  FetchGroup<Customer> FG_CUSTOMER = FetchGroup.of(Customer.class)
  *    .select("name, version")
  *    .fetch("billingAddress", FG_ADDRESS)
  *    .build();
@@ -57,8 +57,10 @@ import javax.annotation.Nonnull;
  *    .findList();
  *
  * }</pre>
+ *
+ * @param <T> The bean type the Fetch group can be applied to
  */
-public interface FetchGroup {
+public interface FetchGroup<T> {
 
   /**
    * Return the FetchGroup with the given select clause.
@@ -67,7 +69,7 @@ public interface FetchGroup {
    * </p>
    * <pre>{@code
    *
-   * FetchGroup fetchGroup = FetchGroup.of("name, status");
+   * FetchGroup<Customer> fetchGroup = FetchGroup.of(Customer.class, "name, status");
    *
    * Customer.query()
    *   .select(fetchGroup)
@@ -80,8 +82,8 @@ public interface FetchGroup {
    * @return The FetchGroup with the given select clause
    */
   @Nonnull
-  static FetchGroup of(String select) {
-    return XServiceProvider.fetchGroupOf(select);
+  static <T> FetchGroup<T> of(Class<T> cls, String select) {
+    return XServiceProvider.fetchGroupOf(cls, select);
   }
 
   /**
@@ -91,7 +93,7 @@ public interface FetchGroup {
    * </p>
    * <pre>{@code
    *
-   * FetchGroup fetchGroup = FetchGroup
+   * FetchGroup<Customer> fetchGroup = FetchGroup.of(Customer.class)
    *   .select("name, status")
    *   .fetch("contacts", "firstName, lastName, email")
    *   .build();
@@ -102,13 +104,11 @@ public interface FetchGroup {
    *
    * }</pre>
    *
-   * @param select The select clause for the FetchGroup
-   *
    * @return The FetchGroupBuilder with the given select clause which we will add fetch clauses to
    */
   @Nonnull
-  static FetchGroupBuilder select(String select) {
-    return XServiceProvider.fetchGroupSelect(select);
+  static <T> FetchGroupBuilder<T> of(Class<T> cls) {
+    return XServiceProvider.fetchGroupOf(cls);
   }
 
 }
diff --git a/src/main/java/io/ebean/FetchGroupBuilder.java b/src/main/java/io/ebean/FetchGroupBuilder.java
index 65ad49bbf..cfe1ebfd8 100644
--- a/src/main/java/io/ebean/FetchGroupBuilder.java
+++ b/src/main/java/io/ebean/FetchGroupBuilder.java
@@ -23,65 +23,71 @@ import javax.annotation.Nonnull;
  *
  * }</pre>
  */
-public interface FetchGroupBuilder {
+public interface FetchGroupBuilder<T> {
 
   /**
-   * Fetch the path including all its properties.
+   * Specify specific properties to select (top level properties).
    */
   @Nonnull
-  FetchGroupBuilder fetch(String path);
+  FetchGroupBuilder<T> select(String select);
+
+  /**
+   * Fetch all the properties at the given path.
+   */
+  @Nonnull
+  FetchGroupBuilder<T> fetch(String path);
 
   /**
    * Fetch the path with the nested fetch group.
    */
   @Nonnull
-  FetchGroupBuilder fetch(String path, FetchGroup nestedGroup);
+  FetchGroupBuilder<T> fetch(String path, FetchGroup nestedGroup);
 
   /**
    * Fetch the path using a query join with the nested fetch group.
    */
   @Nonnull
-  FetchGroupBuilder fetchQuery(String path, FetchGroup nestedGroup);
+  FetchGroupBuilder<T> fetchQuery(String path, FetchGroup nestedGroup);
 
   /**
    * Fetch the path lazily with the nested fetch group.
    */
   @Nonnull
-  FetchGroupBuilder fetchLazy(String path, FetchGroup nestedGroup);
+  FetchGroupBuilder<T> fetchLazy(String path, FetchGroup nestedGroup);
 
   /**
    * Fetch the path including specified properties.
    */
   @Nonnull
-  FetchGroupBuilder fetch(String path, String properties);
+  FetchGroupBuilder<T> fetch(String path, String properties);
 
   /**
    * Fetch the path including all its properties using a query join.
    */
   @Nonnull
-  FetchGroupBuilder fetchQuery(String path);
+  FetchGroupBuilder<T> fetchQuery(String path);
 
   /**
    * Fetch the path including specified properties using a query join.
    */
   @Nonnull
-  FetchGroupBuilder fetchQuery(String path, String properties);
+  FetchGroupBuilder<T> fetchQuery(String path, String properties);
 
   /**
    * Fetch the path including all its properties lazily.
    */
   @Nonnull
-  FetchGroupBuilder fetchLazy(String path);
+  FetchGroupBuilder<T> fetchLazy(String path);
 
   /**
    * Fetch the path including specified properties lazily.
    */
   @Nonnull
-  FetchGroupBuilder fetchLazy(String path, String properties);
+  FetchGroupBuilder<T> fetchLazy(String path, String properties);
 
   /**
    * Build and return the FetchGroup.
    */
   @Nonnull
-  FetchGroup build();
+  FetchGroup<T> build();
 }
diff --git a/src/main/java/io/ebean/Query.java b/src/main/java/io/ebean/Query.java
index 350393776..8749a2213 100644
--- a/src/main/java/io/ebean/Query.java
+++ b/src/main/java/io/ebean/Query.java
@@ -400,7 +400,7 @@ public interface Query<T> {
   /**
    * Apply the fetchGroup which defines what part of the object graph to load.
    */
-  Query<T> select(FetchGroup fetchGroup);
+  Query<T> select(FetchGroup<T> fetchGroup);
 
   /**
    * Specify a path to fetch eagerly including specific properties.
diff --git a/src/main/java/io/ebean/XServiceProvider.java b/src/main/java/io/ebean/XServiceProvider.java
index 53a81993a..81976df38 100644
--- a/src/main/java/io/ebean/XServiceProvider.java
+++ b/src/main/java/io/ebean/XServiceProvider.java
@@ -61,14 +61,14 @@ class XServiceProvider {
   /**
    * Return the FetchGroup with the given select clause.
    */
-  static FetchGroup fetchGroupOf(String select) {
-    return fetchGroupService.of(select);
+  static <T> FetchGroup<T> fetchGroupOf(Class<T> cls, String select) {
+    return fetchGroupService.of(cls, select);
   }
 
   /**
    * Return the FetchGroupBuilder with the given select clause.
    */
-  static FetchGroupBuilder fetchGroupSelect(String select) {
-    return fetchGroupService.select(select);
+  static <T> FetchGroupBuilder<T> fetchGroupOf(Class<T> cls) {
+    return fetchGroupService.of(cls);
   }
 }
diff --git a/src/main/java/io/ebean/service/SpiFetchGroupService.java b/src/main/java/io/ebean/service/SpiFetchGroupService.java
index 813f5244d..b486d4ae1 100644
--- a/src/main/java/io/ebean/service/SpiFetchGroupService.java
+++ b/src/main/java/io/ebean/service/SpiFetchGroupService.java
@@ -10,14 +10,17 @@ public interface SpiFetchGroupService {
 
   /**
    * Return the FetchGroup with the given select clause.
+   *
+   * @param beanType The type of entity bean the fetch group is for
+   * @param select   The properties to select (top level properties)
    */
-  FetchGroup of(String select);
+  <T> FetchGroup<T> of(Class<T> beanType, String select);
 
   /**
    * Create and return a FetchGroupBuilder starting with a select() clause.
    *
-   * @param select The properties to select (top level properties)
-   * @return The FetchGroupBuilder to add additional fetch clauses
+   * @param beanType The type of entity bean the fetch group is for
+   * @return The FetchGroupBuilder to add additional select and fetch clauses
    */
-  FetchGroupBuilder select(String select);
+  <T> FetchGroupBuilder<T> of(Class<T> beanType);
 }
diff --git a/src/main/java/io/ebeaninternal/server/query/DFetchGroup.java b/src/main/java/io/ebeaninternal/server/query/DFetchGroup.java
index 6bd9cbc8e..4b17e3461 100644
--- a/src/main/java/io/ebeaninternal/server/query/DFetchGroup.java
+++ b/src/main/java/io/ebeaninternal/server/query/DFetchGroup.java
@@ -6,7 +6,7 @@ import io.ebeaninternal.server.querydefn.SpiFetchGroup;
 /**
  * Default FetchGroup implementation.
  */
-class DFetchGroup implements SpiFetchGroup {
+class DFetchGroup<T> implements SpiFetchGroup<T> {
 
   private final OrmQueryDetail detail;
 
diff --git a/src/main/java/io/ebeaninternal/server/query/DFetchGroupBuilder.java b/src/main/java/io/ebeaninternal/server/query/DFetchGroupBuilder.java
index 76778ee41..15c876b0d 100644
--- a/src/main/java/io/ebeaninternal/server/query/DFetchGroupBuilder.java
+++ b/src/main/java/io/ebeaninternal/server/query/DFetchGroupBuilder.java
@@ -9,39 +9,46 @@ import io.ebeaninternal.server.querydefn.SpiFetchGroup;
 /**
  * Default implementation of the FetchGroupBuilder.
  */
-class DFetchGroupBuilder implements FetchGroupBuilder {
+class DFetchGroupBuilder<T> implements FetchGroupBuilder<T> {
 
   private static final FetchConfig FETCH_QUERY = new FetchConfig().query();
 
   private static final FetchConfig FETCH_LAZY = new FetchConfig().lazy();
 
-  private OrmQueryDetail detail;
+  private final OrmQueryDetail detail;
 
-  DFetchGroupBuilder(OrmQueryDetail detail) {
-    this.detail = detail;
+  DFetchGroupBuilder() {
+    this.detail = new OrmQueryDetail();
   }
 
   @Override
-  public FetchGroupBuilder fetch(String path) {
+  public FetchGroupBuilder<T> select(String select) {
+    detail.select(select);
+    return this;
+  }
+
+  @Override
+  public FetchGroupBuilder<T> fetch(String path) {
     detail.fetch(path, null, null);
     return this;
   }
 
   @Override
-  public FetchGroupBuilder fetch(String path, FetchGroup nestedGroup) {
+  public FetchGroupBuilder<T> fetch(String path, FetchGroup nestedGroup) {
     return fetchNested(path, nestedGroup, null);
   }
+
   @Override
-  public FetchGroupBuilder fetchQuery(String path, FetchGroup nestedGroup) {
+  public FetchGroupBuilder<T> fetchQuery(String path, FetchGroup nestedGroup) {
     return fetchNested(path, nestedGroup, FETCH_QUERY);
   }
 
   @Override
-  public FetchGroupBuilder fetchLazy(String path, FetchGroup nestedGroup) {
+  public FetchGroupBuilder<T> fetchLazy(String path, FetchGroup nestedGroup) {
     return fetchNested(path, nestedGroup, FETCH_LAZY);
   }
 
-  private FetchGroupBuilder fetchNested(String path, FetchGroup nestedGroup, FetchConfig fetchConfig) {
+  private FetchGroupBuilder<T> fetchNested(String path, FetchGroup nestedGroup, FetchConfig fetchConfig) {
 
     OrmQueryDetail nestedDetail = ((SpiFetchGroup) nestedGroup).underlying();
     detail.addNested(path, nestedDetail, fetchConfig);
@@ -49,37 +56,37 @@ class DFetchGroupBuilder implements FetchGroupBuilder {
   }
 
   @Override
-  public FetchGroupBuilder fetchQuery(String path) {
+  public FetchGroupBuilder<T> fetchQuery(String path) {
     detail.fetch(path, null, FETCH_QUERY);
     return this;
   }
 
   @Override
-  public FetchGroupBuilder fetchLazy(String path) {
+  public FetchGroupBuilder<T> fetchLazy(String path) {
     detail.fetch(path, null, FETCH_LAZY);
     return this;
   }
 
   @Override
-  public FetchGroupBuilder fetch(String path, String properties) {
+  public FetchGroupBuilder<T> fetch(String path, String properties) {
     detail.fetch(path, properties, null);
     return this;
   }
 
   @Override
-  public FetchGroupBuilder fetchQuery(String path, String properties) {
+  public FetchGroupBuilder<T> fetchQuery(String path, String properties) {
     detail.fetch(path, properties, FETCH_QUERY);
     return this;
   }
 
   @Override
-  public FetchGroupBuilder fetchLazy(String path, String properties) {
+  public FetchGroupBuilder<T> fetchLazy(String path, String properties) {
     detail.fetch(path, properties, FETCH_LAZY);
     return this;
   }
 
   @Override
-  public FetchGroup build() {
-    return new DFetchGroup(detail);
+  public FetchGroup<T> build() {
+    return new DFetchGroup<>(detail);
   }
 }
diff --git a/src/main/java/io/ebeaninternal/server/query/DFetchGroupService.java b/src/main/java/io/ebeaninternal/server/query/DFetchGroupService.java
index 62555997d..3dc53a83a 100644
--- a/src/main/java/io/ebeaninternal/server/query/DFetchGroupService.java
+++ b/src/main/java/io/ebeaninternal/server/query/DFetchGroupService.java
@@ -11,13 +11,13 @@ import io.ebeaninternal.server.querydefn.OrmQueryDetail;
 public final class DFetchGroupService implements SpiFetchGroupService {
 
   @Override
-  public FetchGroup of(String select) {
-    return new DFetchGroup(detail(select));
+  public <T> FetchGroup<T> of(Class<T> cls, String select) {
+    return new DFetchGroup<>(detail(select));
   }
 
   @Override
-  public FetchGroupBuilder select(String select) {
-    return new DFetchGroupBuilder(detail(select));
+  public <T> FetchGroupBuilder<T> of(Class<T> cls) {
+    return new DFetchGroupBuilder<>();
   }
 
   private OrmQueryDetail detail(String select) {
diff --git a/src/main/java/io/ebeaninternal/server/querydefn/SpiFetchGroup.java b/src/main/java/io/ebeaninternal/server/querydefn/SpiFetchGroup.java
index 05935e25c..35f622f03 100644
--- a/src/main/java/io/ebeaninternal/server/querydefn/SpiFetchGroup.java
+++ b/src/main/java/io/ebeaninternal/server/querydefn/SpiFetchGroup.java
@@ -5,7 +5,7 @@ import io.ebean.FetchGroup;
 /**
  * Service API of FetchGroup.
  */
-public interface SpiFetchGroup extends FetchGroup {
+public interface SpiFetchGroup<T> extends FetchGroup<T> {
 
   /**
    * Return the detail to use for query execution.
diff --git a/src/test/java/io/ebean/FetchGroupTest.java b/src/test/java/io/ebean/FetchGroupTest.java
index 91bf229b8..148cc7230 100644
--- a/src/test/java/io/ebean/FetchGroupTest.java
+++ b/src/test/java/io/ebean/FetchGroupTest.java
@@ -2,6 +2,8 @@ package io.ebean;
 
 import org.ebeantest.LoggedSqlCollector;
 import org.junit.Test;
+import org.tests.model.basic.Address;
+import org.tests.model.basic.Contact;
 import org.tests.model.basic.Customer;
 import org.tests.model.basic.ResetBasicData;
 
@@ -14,7 +16,7 @@ public class FetchGroupTest extends BaseTestCase {
   @Test
   public void simple() {
 
-    FetchGroup fetch = FetchGroup.of("name, status");
+    FetchGroup<Customer> fetch = FetchGroup.of(Customer.class, "name, status");
 
     Query<Customer> query = Customer.find
       .query()
@@ -33,7 +35,7 @@ public class FetchGroupTest extends BaseTestCase {
 
     ResetBasicData.reset();
 
-    FetchGroup fetch = FetchGroup
+    FetchGroup<Customer> fetch = FetchGroup.of(Customer.class)
       .select("name, status")
       .fetchQuery("contacts", "firstName, lastName, email")
       .build();
@@ -59,9 +61,9 @@ public class FetchGroupTest extends BaseTestCase {
 
     ResetBasicData.reset();
 
-    FetchGroup CT_NAME = FetchGroup.of("firstName, lastName, email");
+    FetchGroup<Contact> CT_NAME = FetchGroup.of(Contact.class, "firstName, lastName, email");
 
-    FetchGroup fetch = FetchGroup
+    FetchGroup<Customer> fetch = FetchGroup.of(Customer.class)
       .select("name")
       .fetchQuery("contacts", CT_NAME)
       .build();
@@ -86,12 +88,12 @@ public class FetchGroupTest extends BaseTestCase {
 
     ResetBasicData.reset();
 
-    FetchGroup FGAddress = FetchGroup
+    FetchGroup<Address> FGAddress = FetchGroup.of(Address.class)
       .select("line1, line2, city")
       .fetch("country", "name")
       .build();
 
-    FetchGroup FBCustomer = FetchGroup
+    FetchGroup<Customer> FBCustomer = FetchGroup.of(Customer.class)
       .select("name, version")
       .fetch("billingAddress", FGAddress)
       .build();