Simple urn directive example

experiments/graphql-tools-mocking.md

@@ -2,18 +2,10 @@
 
 ## Setup
 
-This assumes we are using volta.
-
-Install `ts-node`:
-
-```sh
-$ volta install ts-node
-```
-
 Run the demo (that includes a server) by running:
 
 ```sh
-$ ts-node graphql-tools-mocking/index.ts
+$ yarn ts-node graphql-tools-mocking/index.ts
 ```
 
 You should be able to see the result of the query that was executed directly.

graphql-tools-mocking/index.ts

@@ -1,6 +1,7 @@
 import { makeExecutableSchema } from '@graphql-tools/schema';
 import { addMocksToSchema } from '@graphql-tools/mock';
-import { graphql } from 'graphql';
+import { mapSchema, getDirective, MapperKind } from '@graphql-tools/utils';
+import { graphql, GraphQLSchema, defaultFieldResolver } from 'graphql';
 import { faker } from '@faker-js/faker';
 import { createServer } from '@graphql-yoga/node';
 
@@ -15,6 +16,7 @@ const schemaString = `
     description: String
     date: Date
     author: BookAuthor
+    urn: String @urn(type: "foo", fields: [{ name: "first" }, { name: "last" }])
   }
 
   type BookAuthor {
@@ -35,8 +37,68 @@ const schemaString = `
   }
 `;
 
+let id = 1;
+
+function idGenerator() {
+  return id++;
+}
+
+function urnDirective(schema: GraphQLSchema): GraphQLSchema {
+  const directiveName = 'urn';
+
+  return mapSchema(schema, {
+    [MapperKind.OBJECT_FIELD]: (fieldConfig) => {
+      const urnDirectiveArgs = getDirective(
+        schema,
+        fieldConfig,
+        directiveName
+      )?.[0] as
+        | {
+            type: string;
+            fields?: [];
+          }
+        | undefined;
+
+      if (urnDirectiveArgs) {
+        const { resolve = defaultFieldResolver } = fieldConfig;
+
+        return {
+          ...fieldConfig,
+          resolve: async function (source, args, context, info) {
+            const result = await resolve(source, args, context, info);
+
+            if (typeof result === 'string') {
+              const { type, fields = [] } = urnDirectiveArgs;
+
+              const baseUrn = `unique_urn_with_parts_${type}`;
+
+              if (fields.length) {
+                return `${baseUrn}:(${fields.map(() => idGenerator())})`;
+              }
+
+              return baseUrn;
+            }
+
+            return result;
+          },
+        };
+      }
+    },
+  });
+}
+
+const urnDirectiveTypeDef = () => `
+  directive @urn(type: String!, fields: [FieldMetadata!]) on FIELD_DEFINITION
+
+  input FieldMetadata {
+    name: String
+  }
+`;
+
 // Make a GraphQL schema with no resolvers
-const schema = makeExecutableSchema({ typeDefs: schemaString });
+const schema = makeExecutableSchema({
+  typeDefs: [schemaString, urnDirectiveTypeDef()],
+});
 
 // Create a new schema with mocks
 const schemaWithMocks = addMocksToSchema({
@@ -58,9 +120,11 @@ const schemaWithMocks = addMocksToSchema({
   },
 });
 
+const schemaWithUrnDirective = urnDirective(schemaWithMocks);
+
 // optionally we can serve the schema in the network
 const server = createServer({
-  schema: schemaWithMocks,
+  schema: schemaWithUrnDirective,
 });
 
 server.start();
@@ -71,6 +135,7 @@ const query = /* GraphQL */ `
       id
       description
       date
+      urn
       author {
         id
         firstName
@@ -82,7 +147,7 @@ const query = /* GraphQL */ `
 `;
 
 graphql({
-  schema: schemaWithMocks,
+  schema: schemaWithUrnDirective,
   source: query,
 }).then((result) => {
   console.log('Got result %o', result);

package.json

@@ -35,7 +35,8 @@
     "graphql": "^16.5.0",
     "graphql-faker": "^2.0.0-rc.25",
     "graphql-mocks": "^0.8.4",
-    "prettier": "^2.7.1"
+    "prettier": "^2.7.1",
+    "ts-node": "^10.9.1"
   },
   "dependencies": {
     "typescript": "^4.8.2"

tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "compilerOptions": {
+    "target": "es2016",
+    "module": "commonjs",
+    "esModuleInterop": true,
+    "strict": true,
+    "skipLibCheck": true
+  }
+}

yarn.lock

@@ -3268,7 +3268,7 @@ tr46@~0.0.3:
   resolved "https://registry.yarnpkg.com/tr46/-/tr46-0.0.3.tgz#8184fd347dac9cdc185992f3a6622e14b9d9ab6a"
   integrity sha512-N3WMsuqV66lT30CrXNbEjx4GEwlow3v6rr4mCcv6prnfwhS01rkgyFdjPNBYd9br7LpXV1+Emh01fHnq2Gdgrw==
 
-ts-node@^10.5.0:
+ts-node@^10.5.0, ts-node@^10.9.1:
   version "10.9.1"
   resolved "https://registry.yarnpkg.com/ts-node/-/ts-node-10.9.1.tgz#e73de9102958af9e1f0b168a6ff320e25adcff4b"
   integrity sha512-NtVysVPkxxrwFGUUxGYhfux8k78pQB3JqYBXlLRZgdGUqTO5wU/UyHop5p70iEbGhB7q5KmiZiU0Y3KlJrScEw==