Issue-8: implement mapping of entity key ids to alias

Author: Carlo Feliciano Aureus

src/main/java/com/intuit/graphql/orchestrator/batch/EntityFetcherBatchLoader.java

@@ -14,6 +14,7 @@
 import com.intuit.graphql.orchestrator.schema.ServiceMetadata;
 import graphql.GraphQLContext;
 import graphql.execution.DataFetcherResult;
+import graphql.execution.MergedField;
 import graphql.introspection.Introspection;
 import graphql.language.Field;
 import graphql.language.InlineFragment;
@@ -58,9 +59,7 @@ public CompletionStage<List<DataFetcherResult<Object>>> load(List<DataFetchingEn
         GraphQLContext graphQLContext = dfeTemplate.getContext();
 
         List<Map<String, Object>> representations = dataFetchingEnvironments.stream()
-            //.map(DataFetchingEnvironment::getSource)
-            .map(dataFetchingEnvironment -> getSource(dataFetchingEnvironment))
-            .map(source -> createRepresentation((Map<String, Object>) source))
+            .map(dataFetchingEnvironment -> createRepresentation(dataFetchingEnvironment))
             .collect(Collectors.toList());
 
         List<InlineFragment> inlineFragments = new ArrayList<>();
@@ -78,12 +77,6 @@ public CompletionStage<List<DataFetcherResult<Object>>> load(List<DataFetchingEn
         .thenApply(result -> batchResultTransformer.toBatchResult(result, dataFetchingEnvironments));
     }
 
-    private Map<String, Object> getSource(DataFetchingEnvironment dataFetchingEnvironment) {
-        // TODO
-        // return a POJO with source, and metadata about alias mapping.
-        return dataFetchingEnvironment.getSource();
-    }
-
     private List<String> generateRepresentationTemplate(FederationMetadata.EntityExtensionMetadata metadata, String fieldName) {
         List<String> representationFields = new ArrayList<>();
 
@@ -140,20 +133,43 @@ private InlineFragment createEntityRequestInlineFragment(DataFetchingEnvironment
                                 newField()
                                         .selectionSet(fieldSelectionSet)
                                         .name(originalField.getName())
+                                        .alias(originalField.getAlias())
                                         .build())
                         .build());
         return inlineFragmentBuilder.build();
     }
 
     private Map<String, Object> createRepresentation(
-            Map<String, Object> dataSource
+        DataFetchingEnvironment dataFetchingEnvironment
     ){
+        Map<String, Object> dataSource = dataFetchingEnvironment.getSource();
+        Map<String, String> fieldToAliasMap = buildFieldToAliasMap(dataFetchingEnvironment);
+
         Map<String, Object> entityRepresentation = new HashMap<>();
         entityRepresentation.put(Introspection.TypeNameMetaFieldDef.getName(), this.entityTypeName);
 
         this.representationFieldTemplate
-                .forEach(fieldName -> entityRepresentation.put(fieldName, dataSource.get(fieldName)));
+            .forEach(fieldName -> {
+                String dataSourceKey = fieldToAliasMap.get(fieldName);
+                entityRepresentation.put(fieldName, dataSource.get(dataSourceKey));
+            });
 
         return entityRepresentation;
     }
+
+    /**
+     * builds mapping of fieldName-alias.  If fieldName has no alias, it will be mapped to itself.
+     *
+     * @param dataFetchingEnvironment
+     * @return
+     */
+    private Map<String, String> buildFieldToAliasMap(DataFetchingEnvironment dataFetchingEnvironment) {
+        MergedField parentField = dataFetchingEnvironment.getExecutionStepInfo().getParent().getField();
+        return parentField.getSingleField().getSelectionSet().getSelections()
+            .stream()
+            .filter(selection -> selection instanceof Field)
+            .map(selection -> (Field) selection)
+            .filter(field -> this.representationFieldTemplate.contains(field.getName()))
+            .collect(Collectors.toMap(field -> field.getName(), field -> field.getAlias() == null? field.getName() : field.getAlias()));
+    }
 }

src/main/java/com/intuit/graphql/orchestrator/batch/EntityFetcherBatchResultTransformer.java

@@ -3,6 +3,7 @@
 import com.intuit.graphql.orchestrator.federation.EntityFetchingException;
 import graphql.GraphQLError;
 import graphql.execution.DataFetcherResult;
+import graphql.language.Field;
 import graphql.schema.DataFetchingEnvironment;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.commons.collections4.CollectionUtils;
@@ -54,8 +55,13 @@ public List<DataFetcherResult<Object>> toBatchResult(DataFetcherResult<Map<Strin
 
         //using IntStream instead of regular for loop or atomic reference, so we can parallelize this if we want
         IntStream.range(0, _entities.size()).forEach( idx -> {
+
+            DataFetchingEnvironment dataFetchingEnvironment = dataFetchingEnvironments.get(idx);
+            Field field = dataFetchingEnvironment.getField();
+            String fieldNameOrAlias = field.getAlias() == null ? field.getName() : field.getAlias();
+
             Map<String, Object> entityInfo = _entities.get(idx);
-            Object fieldData = (entityInfo != null) ? entityInfo.get(this.extFieldName) : null;
+            Object fieldData = (entityInfo != null) ? entityInfo.get(fieldNameOrAlias) : null;
             List<GraphQLError> graphQLErrors = (List<GraphQLError>) entityInfo.getOrDefault("errors", new ArrayList<>());
 
             dataFetcherResults.add(DataFetcherResult.newResult()

src/test/groovy/com/intuit/graphql/orchestrator/integration/federation/FederatedQueryWithKeyAliasedSimpleSpec.groovy

@@ -16,8 +16,6 @@ import helpers.BaseIntegrationTestSpecification
 
 class FederatedQueryWithKeyAliasedSimpleSpec extends BaseIntegrationTestSpecification {
 
-    Parser parser = GraphQLUtil.parser
-
     GraphQLOrchestrator specUnderTest
 
     private def bookSchema = '''
@@ -62,7 +60,7 @@ class FederatedQueryWithKeyAliasedSimpleSpec extends BaseIntegrationTestSpecific
                                 name     : "GraphQuilt: The future of Schema Stitching",
                                 pageCount: 100,
                                 author   : [
-                                        "author": "12345"
+                                        "authorId": "12345"
                                 ]
                         ]
 
@@ -79,8 +77,7 @@ class FederatedQueryWithKeyAliasedSimpleSpec extends BaseIntegrationTestSpecific
                                 [
                                         __typename: "Author",
                                         id        : "12345",
-                                        firstName : "Charles",
-                                        lastName  : "Wayne"
+                                        authorName : "Charles"
                                 ]
                         ]
                 ]
@@ -113,7 +110,7 @@ class FederatedQueryWithKeyAliasedSimpleSpec extends BaseIntegrationTestSpecific
 
         then:
 
-        def AUTHOR_QUERY = "query (\$REPRESENTATIONS:[_Any!]!) {_entities(representations:\$REPRESENTATIONS) {... on Author {firstName}}}"
+        def AUTHOR_QUERY = "query (\$REPRESENTATIONS:[_Any!]!) {_entities(representations:\$REPRESENTATIONS) {... on Author {authorName:firstName}}}"
 
         executionResult.get("errors") == null
         executionResult.get("data") != null