Fix handling of concrete type datafetchers for interface fields. (#1693)

graphql-dgs-example-shared/src/main/java/com/netflix/graphql/dgs/example/shared/datafetcher/ActionMovieDataFetcher.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2021 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.netflix.graphql.dgs.example.shared.datafetcher;
+
+import com.netflix.graphql.dgs.DgsComponent;
+import com.netflix.graphql.dgs.DgsData;
+
+@DgsComponent
+public class ActionMovieDataFetcher {
+    @SuppressWarnings("SameReturnValue")
+    @DgsData(parentType = "ActionMovie", field = "director")
+    public String director() {
+
+        return "Action movie director";
+    }
+}

graphql-dgs-example-shared/src/main/java/com/netflix/graphql/dgs/example/shared/datafetcher/ScaryMovieDataFetcher.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2021 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.netflix.graphql.dgs.example.shared.datafetcher;
+
+import com.netflix.graphql.dgs.DgsComponent;
+import com.netflix.graphql.dgs.DgsData;
+import com.netflix.graphql.dgs.example.shared.types.ActionMovie;
+import com.netflix.graphql.dgs.example.shared.types.Movie;
+import com.netflix.graphql.dgs.example.shared.types.ScaryMovie;
+import graphql.schema.DataFetchingEnvironment;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@DgsComponent
+public class ScaryMovieDataFetcher {
+    @SuppressWarnings("SameReturnValue")
+    @DgsData(parentType = "ScaryMovie", field = "director")
+    public String director() {
+
+        return "Scary movie director";
+    }
+}

graphql-dgs/src/main/kotlin/com/netflix/graphql/dgs/internal/DgsSchemaProvider.kt

@@ -368,14 +368,20 @@ class DgsSchemaProvider(
                     }
                     val implementationsOf = typeDefinitionRegistry.getImplementationsOf(type)
                     implementationsOf.forEach { implType ->
-                        val dataFetcher =
-                            createBasicDataFetcher(method, dgsComponent, parentType == "Subscription")
-                        codeRegistryBuilder.dataFetcher(
-                            FieldCoordinates.coordinates(implType.name, field),
-                            dataFetcher
-                        )
-                        dataFetcherTracingInstrumentationEnabled["${implType.name}.$field"] = enableTracingInstrumentation
-                        dataFetcherMetricsInstrumentationEnabled["${implType.name}.$field"] = enableMetricsInstrumentation
+                        // if we have a datafetcher explicitly defined for a parentType/field, use that and do not
+                        // register the base implementation for interfaces
+                        if (!codeRegistryBuilder.hasDataFetcher(FieldCoordinates.coordinates(implType.name, field))) {
+                            val dataFetcher =
+                                createBasicDataFetcher(method, dgsComponent, parentType == "Subscription")
+                            codeRegistryBuilder.dataFetcher(
+                                FieldCoordinates.coordinates(implType.name, field),
+                                dataFetcher
+                            )
+                            dataFetcherTracingInstrumentationEnabled["${implType.name}.$field"] =
+                                enableTracingInstrumentation
+                            dataFetcherMetricsInstrumentationEnabled["${implType.name}.$field"] =
+                                enableMetricsInstrumentation
+                        }
                     }
                 }
                 is UnionTypeDefinition -> {