Error relationship on relationship properties

packages/graphql/src/schema/make-augmented-schema.test.ts

@@ -209,7 +209,7 @@ describe("makeAugmentedSchema", () => {
         });
     });
 
-    test("should throw error if auth is used on relationship properties interface", () => {
+    test("should throw error if @auth is used on relationship properties interface", () => {
         const typeDefs = `
             type Movie {
                 actors: Actor @relationship(type: "ACTED_IN", direction: OUT, properties: "ActedIn")
@@ -229,7 +229,7 @@ describe("makeAugmentedSchema", () => {
         );
     });
 
-    test("should throw error if auth is used on relationship property", () => {
+    test("should throw error if @auth is used on relationship property", () => {
         const typeDefs = `
             type Movie {
                 actors: Actor @relationship(type: "ACTED_IN", direction: OUT, properties: "ActedIn")
@@ -246,4 +246,24 @@ describe("makeAugmentedSchema", () => {
 
         expect(() => makeAugmentedSchema({ typeDefs })).toThrow("Cannot have @auth directive on relationship property");
     });
+
+    test("should throw error if @relationship is used on relationship property", () => {
+        const typeDefs = `
+            type Movie {
+                actors: Actor @relationship(type: "ACTED_IN", direction: OUT, properties: "ActedIn")
+            }
+
+            type Actor {
+                name: String
+            }
+
+            interface ActedIn {
+                actors: Actor @relationship(type: "ACTED_IN", direction: OUT, properties: "ActedIn")
+            }
+        `;
+
+        expect(() => makeAugmentedSchema({ typeDefs })).toThrow(
+            "Cannot have @relationship directive on relationship property"
+        );
+    });
 });

packages/graphql/src/schema/make-augmented-schema.ts

@@ -277,10 +277,13 @@ function makeAugmentedSchema(
         const fields = {};
 
         relationship.fields?.forEach((field) => {
-            const authDirective = (field.directives || []).find((x) => x.name.value === "auth");
-            if (authDirective) {
-                throw new Error("Cannot have @auth directive on relationship property");
-            }
+            const forbiddenDirectives = ["auth", "relationship"];
+            forbiddenDirectives.forEach((directive) => {
+                const found = (field.directives || []).find((x) => x.name.value === directive);
+                if (found) {
+                    throw new Error(`Cannot have @${directive} directive on relationship property`);
+                }
+            });
 
             const typeMeta = getFieldTypeMeta(field);