DATAMONGO-2096 - Fix target field name for GraphLookup aggregation operation.

We now make sure to use the target field name instead of the alias when processing GraphLookupOperation.

Original pull request: #613.

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/GraphLookupOperation.java

@@ -104,16 +104,16 @@ public DBObject toDBObject(AggregationOperationContext context) {
 
 		graphLookup.put("startWith", mappedStartWith.size() == 1 ? mappedStartWith.iterator().next() : mappedStartWith);
 
-		graphLookup.put("connectFromField", connectFrom.getName());
-		graphLookup.put("connectToField", connectTo.getName());
+		graphLookup.put("connectFromField", connectFrom.getTarget());
+		graphLookup.put("connectToField", connectTo.getTarget());
 		graphLookup.put("as", as.getName());
 
 		if (maxDepth != null) {
 			graphLookup.put("maxDepth", maxDepth);
 		}
 
 		if (depthField != null) {
-			graphLookup.put("depthField", depthField.getName());
+			graphLookup.put("depthField", depthField.getTarget());
 		}
 
 		if (restrictSearchWithMatch != null) {

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/GraphLookupOperationUnitTests.java

@@ -133,4 +133,40 @@ public void shouldRenderStartWithAggregationExpressions() {
 		assertThat(dbObject, is(JSON.parse("{ $graphLookup : { from: \"employees\", startWith: { $literal: \"hello\"}, "
 				+ "connectFromField: \"reportsTo\", connectToField: \"name\", as: \"reportingHierarchy\" } }")));
 	}
+
+	@Test // DATAMONGO-2096
+	public void connectFromShouldUseTargetFieldInsteadOfAlias() {
+
+		AggregationOperation graphLookupOperation = Aggregation.graphLookup("user").startWith("contacts.userId")
+				.connectFrom("contacts.userId").connectTo("_id").depthField("numConnections").as("connections");
+
+		DBObject document = graphLookupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT);
+
+		assertThat(document, is(JSON.parse(
+				"{ \"$graphLookup\" : { \"from\" : \"user\", \"startWith\" : \"$contacts.userId\", \"connectFromField\" : \"contacts.userId\", \"connectToField\" : \"_id\", \"as\" : \"connections\", \"depthField\" : \"numConnections\" } }")));
+	}
+
+	@Test // DATAMONGO-2096
+	public void connectToShouldUseTargetFieldInsteadOfAlias() {
+
+		AggregationOperation graphLookupOperation = Aggregation.graphLookup("user").startWith("contacts.userId")
+				.connectFrom("userId").connectTo("connectto.field").depthField("numConnections").as("connections");
+
+		DBObject document = graphLookupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT);
+
+		assertThat(document, is(JSON.parse(
+				"{ \"$graphLookup\" : { \"from\" : \"user\", \"startWith\" : \"$contacts.userId\", \"connectFromField\" : \"userId\", \"connectToField\" : \"connectto.field\", \"as\" : \"connections\", \"depthField\" : \"numConnections\" } }")));
+	}
+
+	@Test // DATAMONGO-2096
+	public void depthFieldShouldUseTargetFieldInsteadOfAlias() {
+
+		AggregationOperation graphLookupOperation = Aggregation.graphLookup("user").startWith("contacts.userId")
+				.connectFrom("contacts.userId").connectTo("_id").depthField("foo.bar").as("connections");
+
+		DBObject document = graphLookupOperation.toDBObject(Aggregation.DEFAULT_CONTEXT);
+
+		assertThat(document, is(JSON.parse(
+				"{ \"$graphLookup\" : { \"from\" : \"user\", \"startWith\" : \"$contacts.userId\", \"connectFromField\" : \"contacts.userId\", \"connectToField\" : \"_id\", \"as\" : \"connections\", \"depthField\" : \"foo.bar\" } }")));
+	}
 }