#1460 - ENH: Add FetchGroup ... as a mechanism to specify select() + fetch() separately from Query

Change to add generics for FetchGroup

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;
 

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);
   }
 }

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) {

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.