De-duplicate relationship projection when not using connection API

.changeset/few-sloths-battle.md

@@ -0,0 +1,7 @@
+---
+"@neo4j/graphql": major
+---
+
+Changes the result projection where there are multiple relationships between two nodes.
+
+In the case of using the connection API then multiple relationships will still be represented, as there is the ability to select the relationship properties. In the non-connection API case, the duplicate results will only return distinct results.

packages/graphql/src/translate/queryAST/ast/operations/ReadOperation.ts

@@ -92,20 +92,13 @@ export class ReadOperation extends Operation {
         return filterTruthy(this.authFilters.map((f) => f.getPredicate(context)));
     }
 
-    protected getProjectionClause(
-        context: QueryASTContext,
-        returnVariable: Cypher.Variable,
-        isArray: boolean
-    ): Cypher.Return {
+    protected getProjectionClause(context: QueryASTContext, returnVariable: Cypher.Variable): Cypher.Return {
         if (!hasTarget(context)) {
             throw new Error("No parent node found!");
         }
         const projection = this.getProjectionMap(context);
 
-        let aggregationExpr: Cypher.Expr = Cypher.collect(context.target);
-        if (!isArray) {
-            aggregationExpr = Cypher.head(aggregationExpr);
-        }
+        const aggregationExpr = Cypher.collect(context.target);
 
         const withClause = new Cypher.With([projection, context.target]);
         if (this.sortFields.length > 0 || this.pagination) {
@@ -148,7 +141,7 @@ export class ReadOperation extends Operation {
 
         const authFiltersPredicate = this.getAuthFilterPredicate(nestedContext);
         const ret: Cypher.Return = this.relationship
-            ? this.getProjectionClause(nestedContext, context.returnVariable, this.relationship.isList)
+            ? this.getProjectionClause(nestedContext, context.returnVariable)
             : this.getReturnStatement(
                   isCreateSelection || isUpdateSelection ? context : nestedContext,
                   nestedContext.returnVariable
@@ -215,6 +208,11 @@ export class ReadOperation extends Operation {
             }
             matchBlock.push(...extraMatches, extraMatchesWith);
 
+            if (this.relationship) {
+                const distinctTargetWith = new Cypher.With(nestedContext.target).distinct();
+                matchBlock.push(distinctTargetWith);
+            }
+
             clause = Cypher.utils.concat(
                 ...matchBlock,
                 ...authFilterSubqueries,

packages/graphql/tests/integration/directives/relationship/duplicate-relationship/duplicate-relationship-create.int.test.ts

@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * 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.
+ */
+
+import type { UniqueType } from "../../../../utils/graphql-types";
+import { TestHelper } from "../../../../utils/tests-helper";
+
+describe("Create: Multiple relationships results difference between Connection API and Simple API", () => {
+    const testHelper: TestHelper = new TestHelper();
+    const Movie: UniqueType = testHelper.createUniqueType("Movie");
+    const Actor: UniqueType = testHelper.createUniqueType("Actor");
+
+    beforeEach(async () => {
+        const typeDefs = /* GraphQL */ `
+            type ${Movie} @node {
+                title: String!
+                actors: [${Actor}!]! @relationship(type: "ACTED_IN", properties: "ActedIn", direction: IN)
+            }
+
+            type ${Actor} @node {
+                name: String!
+                movies: [${Movie}!]! @relationship(type: "ACTED_IN", properties: "ActedIn", direction: OUT)
+            }
+
+            type ActedIn @relationshipProperties {
+                role: String!
+            }
+        `;
+        await testHelper.initNeo4jGraphQL({ typeDefs });
+    });
+
+    afterEach(async () => {
+        await testHelper.close();
+    });
+
+    test("should return multiple relationship results for connection API", async () => {
+        const source = /* GraphQL */ `
+            mutation {
+                ${Movie.operations.create}(
+                    input: [
+                        {
+                            title: "Movie One"
+                            actors: {
+                                create: [{ edge: { role: "Role One" }, node: { name: "Actor One" } }]
+                                connect: [{ edge: { role: "Role Two" } }]
+                            }
+                        }
+                    ]
+                ) {
+                    ${Movie.plural} {
+                        title
+                        actorsConnection {
+                            edges {
+                                properties {
+                                    role
+                                }
+                                node {
+                                    name
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        `;
+
+        const gqlResult = await testHelper.executeGraphQL(source);
+
+        expect(gqlResult.errors).toBeFalsy();
+        expect(gqlResult.data).toEqual({
+            [Movie.operations.create]: {
+                [Movie.plural]: [
+                    {
+                        title: "Movie One",
+                        actorsConnection: {
+                            edges: expect.toIncludeSameMembers([
+                                {
+                                    node: {
+                                        name: "Actor One",
+                                    },
+                                    properties: {
+                                        role: "Role One",
+                                    },
+                                },
+                                {
+                                    node: {
+                                        name: "Actor One",
+                                    },
+                                    properties: {
+                                        role: "Role Two",
+                                    },
+                                },
+                            ]),
+                        },
+                    },
+                ],
+            },
+        });
+    });
+
+    test("should only return a single relationship result for simple API", async () => {
+        const source = /* GraphQL */ `
+            mutation {
+                ${Movie.operations.create}(
+                    input: [
+                        {
+                            title: "Movie One"
+                            actors: {
+                                create: [{ edge: { role: "Role One" }, node: { name: "Actor One" } }]
+                                connect: [{ edge: { role: "Role Two" } }]
+                            }
+                        }
+                    ]
+                ) {
+                    ${Movie.plural} {
+                        title
+                        actors {
+                            name
+                        }
+                    }
+                }
+            }
+        `;
+
+        const gqlResult = await testHelper.executeGraphQL(source);
+
+        expect(gqlResult.errors).toBeFalsy();
+        expect(gqlResult.data).toEqual({
+            [Movie.operations.create]: {
+                [Movie.plural]: [
+                    {
+                        title: "Movie One",
+                        actors: [
+                            {
+                                name: "Actor One",
+                            },
+                        ],
+                    },
+                ],
+            },
+        });
+    });
+});