Support single source ID in new batch hydrator

lib/src/main/java/graphql/nadel/engine/transform/hydration/batch/NadelNewBatchHydrator.kt

@@ -231,15 +231,16 @@ internal class NadelNewBatchHydrator(
             fieldName = state.hydratedField.name,
         )
 
+        val fieldSource = instructions
+            .first()
+            .actorInputValueDefs
+            .asSequence()
+            .map {
+                it.valueSource
+            }
+            .singleOfType<ValueSource.FieldResultValue>()
+
         return if (executionBlueprint.engineSchema.getField(coords)!!.type.unwrapNonNull().isList) {
-            val fieldSource = instructions
-                .first()
-                .actorInputValueDefs
-                .asSequence()
-                .map {
-                    it.valueSource
-                }
-                .singleOfType<ValueSource.FieldResultValue>()
 
             // todo: move this to validation
             instructions
@@ -261,7 +262,18 @@ internal class NadelNewBatchHydrator(
                     sourceId to instruction
                 }
         } else {
-            throw UnsupportedOperationException("todo")
+            // todo: determine what to do here in the longer term, this hook should probably be replaced
+            val instruction = state.executionContext.hooks.getHydrationInstruction(
+                instructions = instructions,
+                parentNode = parentNode,
+                aliasHelper = state.aliasHelper,
+                userContext = state.executionContext.userContext,
+            )!!
+
+            extractValues(parentNode, fieldSource, state.aliasHelper)
+                .map { sourceId ->
+                    sourceId to instruction
+                }
         }
     }
 

test/src/test/kotlin/graphql/nadel/tests/hooks/new-batching-single-source-id.kt

@@ -0,0 +1,53 @@
+package graphql.nadel.tests.hooks
+
+import graphql.nadel.Nadel
+import graphql.nadel.NadelExecutionHints
+import graphql.nadel.engine.blueprint.NadelGenericHydrationInstruction
+import graphql.nadel.engine.blueprint.hydration.NadelHydrationActorInputDef.ValueSource
+import graphql.nadel.engine.transform.artificial.NadelAliasHelper
+import graphql.nadel.engine.transform.result.json.JsonNode
+import graphql.nadel.engine.transform.result.json.JsonNodeExtractor
+import graphql.nadel.engine.util.singleOfType
+import graphql.nadel.hooks.NadelExecutionHooks
+import graphql.nadel.tests.EngineTestHook
+import graphql.nadel.tests.UseHook
+
+@UseHook
+class `new-batching-single-source-id` : EngineTestHook {
+    override fun makeExecutionHints(builder: NadelExecutionHints.Builder): NadelExecutionHints.Builder {
+        return super.makeExecutionHints(builder)
+            .newBatchHydrationGrouping { true }
+    }
+
+    override fun makeNadel(builder: Nadel.Builder): Nadel.Builder {
+        return super.makeNadel(builder)
+            .executionHooks(
+                object : NadelExecutionHooks {
+                    override fun <T : NadelGenericHydrationInstruction> getHydrationInstruction(
+                        instructions: List<T>,
+                        parentNode: JsonNode,
+                        aliasHelper: NadelAliasHelper,
+                        userContext: Any?,
+                    ): T? {
+                        return instructions
+                            .single { instruction ->
+                                val fieldSource = instruction.actorInputValueDefs
+                                    .asSequence()
+                                    .map {
+                                        it.valueSource
+                                    }
+                                    .singleOfType<ValueSource.FieldResultValue>()
+
+                                val sourceNodes = JsonNodeExtractor.getNodesAt(
+                                    parentNode,
+                                    aliasHelper.getQueryPath(fieldSource.queryPathToField)
+                                )
+                                val sourceIdType = (sourceNodes.single().value as String).substringBefore("/")
+
+                                instruction.actorService.name.startsWith(sourceIdType)
+                            }
+                    }
+                },
+            )
+    }
+}

test/src/test/resources/fixtures/hydration/new batching/new-batching-single-source-id.yml

@@ -0,0 +1,235 @@
+name: "new batching single source id"
+enabled: true
+overallSchema:
+  # language=GraphQL
+  activity: |
+    type Query {
+      activity: [Activity]
+    }
+    union ActivityContent = Issue | Comment
+    type Activity {
+      id: ID!
+      contentId: ID!
+      content: ActivityContent
+        @hydrated(
+          service: "comments"
+          field: "commentsByIds"
+          arguments: [
+            {name: "ids" value: "$source.contentId"}
+          ]
+        )
+        @hydrated(
+          service: "issues"
+          field: "issuesByIds"
+          arguments: [
+            {name: "ids" value: "$source.contentId"}
+          ]
+        )
+    }
+  # language=GraphQL
+  issues: |
+    type Query {
+      issuesByIds(ids: [ID!]!): [Issue!]
+    }
+    type Issue {
+      id: ID!
+      title: String
+    }
+  # language=GraphQL
+  comments: |
+    type Query {
+      commentsByIds(ids: [ID!]!): [Comment!]
+    }
+    type Comment {
+      id: ID!
+      content: String
+    }
+underlyingSchema:
+  # language=GraphQL
+  activity: |
+    type Query {
+      activity: [Activity]
+    }
+    type Activity {
+      id: ID!
+      contentId: ID!
+    }
+  # language=GraphQL
+  issues: |
+    type Query {
+      issuesByIds(ids: [ID!]!): [Issue!]
+    }
+    type Issue {
+      id: ID!
+      title: String
+    }
+  # language=GraphQL
+  comments: |
+    type Query {
+      commentsByIds(ids: [ID!]!): [Comment!]
+    }
+    type Comment {
+      id: ID!
+      content: String
+    }
+# language=GraphQL
+query: |
+  {
+    activity {
+      content {
+        __typename
+        ... on Issue {
+          id
+          title
+        }
+        ... on Comment {
+          id
+          content
+        }
+      }
+    }
+  }
+variables: { }
+serviceCalls:
+  - serviceName: "activity"
+    request:
+      # language=GraphQL
+      query: |
+        {
+          activity {
+            __typename__batch_hydration__content: __typename
+            batch_hydration__content__contentId: contentId
+            batch_hydration__content__contentId: contentId
+          }
+        }
+      variables: { }
+    # language=JSON
+    response: |-
+      {
+        "data": {
+          "activity": [
+            {
+              "__typename__batch_hydration__content": "Activity",
+              "batch_hydration__content__contentId": "issue/4000"
+            },
+            {
+              "__typename__batch_hydration__content": "Activity",
+              "batch_hydration__content__contentId": "issue/8080"
+            },
+            {
+              "__typename__batch_hydration__content": "Activity",
+              "batch_hydration__content__contentId": "issue/7496"
+            },
+            {
+              "__typename__batch_hydration__content": "Activity",
+              "batch_hydration__content__contentId": "comment/1234"
+            }
+          ]
+        },
+        "extensions": {}
+      }
+  - serviceName: "issues"
+    request:
+      # language=GraphQL
+      query: |
+        {
+          issuesByIds(ids: ["issue/4000", "issue/8080", "issue/7496"]) {
+            __typename
+            id
+            batch_hydration__content__id: id
+            title
+          }
+        }
+      variables: { }
+    # language=JSON
+    response: |-
+      {
+        "data": {
+          "issuesByIds": [
+            {
+              "__typename": "Issue",
+              "id": "issue/4000",
+              "batch_hydration__content__id": "issue/4000",
+              "title": "Four Thousand"
+            },
+            {
+              "__typename": "Issue",
+              "id": "issue/8080",
+              "batch_hydration__content__id": "issue/8080",
+              "title": "Eighty Eighty"
+            },
+            {
+              "__typename": "Issue",
+              "id": "issue/7496",
+              "batch_hydration__content__id": "issue/7496",
+              "title": "Seven Four Nine Six"
+            }
+          ]
+        },
+        "extensions": {}
+      }
+  - serviceName: "comments"
+    request:
+      # language=GraphQL
+      query: |
+        {
+          commentsByIds(ids: ["comment/1234"]) {
+            __typename
+            content
+            id
+            batch_hydration__content__id: id
+          }
+        }
+      variables: { }
+    # language=JSON
+    response: |-
+      {
+        "data": {
+          "commentsByIds": [
+            {
+              "__typename": "Comment",
+              "id": "comment/1234",
+              "batch_hydration__content__id": "comment/1234",
+              "content": "One Two Three Four"
+            }
+          ]
+        },
+        "extensions": {}
+      }
+# language=JSON
+response: |-
+  {
+    "data": {
+      "activity": [
+        {
+          "content": {
+            "__typename": "Issue",
+            "id": "issue/4000",
+            "title": "Four Thousand"
+          }
+        },
+        {
+          "content": {
+            "__typename": "Issue",
+            "id": "issue/8080",
+            "title": "Eighty Eighty"
+          }
+        },
+        {
+          "content": {
+            "__typename": "Issue",
+            "id": "issue/7496",
+            "title": "Seven Four Nine Six"
+          }
+        },
+        {
+          "content": {
+            "__typename": "Comment",
+            "id": "comment/1234",
+            "content": "One Two Three Four"
+          }
+        }
+      ]
+    },
+    "errors": []
+  }