feat(server): Use validate option for custom GraphQL validation

README.md

@@ -1042,10 +1042,35 @@ useServer(
 );
 ```
 
+<details id="custom-validation">
+<summary><a href="#custom-validation">🔗</a> <a href="https://github.com/websockets/ws">ws</a> server usage with custom validation</summary>
+
+```typescript
+import { execute, subscribe, validate } from 'graphql';
+import ws from 'ws'; // yarn add ws
+import { useServer } from 'graphql-ws/lib/use/ws';
+import { schema, myValidationRules } from './my-graphql';
+
+const wsServer = new ws.Server({
+  port: 443,
+  path: '/graphql',
+});
+
+useServer(
+  {
+    execute,
+    subscribe,
+    validate: (schema, document) =>
+      validate(schema, document, myValidationRules),
+  },
+  wsServer,
+);
+```
+
 </details>
 
 <details id="custom-exec">
-<summary><a href="#custom-exec">🔗</a> <a href="https://github.com/websockets/ws">ws</a> server usage with custom execution arguments and validation</summary>
+<summary><a href="#custom-exec">🔗</a> <a href="https://github.com/websockets/ws">ws</a> server usage with custom execution arguments</summary>
 
 ```typescript
 import { parse, validate, execute, subscribe } from 'graphql';

docs/interfaces/server.serveroptions.md

@@ -28,6 +28,7 @@ Name | Default |
 - [roots](server.serveroptions.md#roots)
 - [schema](server.serveroptions.md#schema)
 - [subscribe](server.serveroptions.md#subscribe)
+- [validate](server.serveroptions.md#validate)
 
 ## Properties
 
@@ -451,3 +452,38 @@ Name | Type |
 `args` | ExecutionArgs |
 
 **Returns:** [*OperationResult*](../modules/server.md#operationresult)
+
+___
+
+### validate
+
+• `Optional` **validate**: (`schema`: *GraphQLSchema*, `documentAST`: DocumentNode, `rules?`: readonly ValidationRule[], `typeInfo?`: *TypeInfo*, `options?`: { `maxErrors?`: *number*  }) => readonly *GraphQLError*[]
+
+A custom GraphQL validate function allowing you to apply your
+own validation rules.
+
+Returned, non-empty, array of `GraphQLError`s will be communicated
+to the client through the `ErrorMessage`. Use an empty array if the
+document is valid and no errors have been encountered.
+
+Will not be used when implementing a custom `onSubscribe`.
+
+Throwing an error from within this function will close the socket
+with the `Error` message in the close event reason.
+
+#### Type declaration:
+
+▸ (`schema`: *GraphQLSchema*, `documentAST`: DocumentNode, `rules?`: readonly ValidationRule[], `typeInfo?`: *TypeInfo*, `options?`: { `maxErrors?`: *number*  }): readonly *GraphQLError*[]
+
+#### Parameters:
+
+Name | Type |
+:------ | :------ |
+`schema` | *GraphQLSchema* |
+`documentAST` | DocumentNode |
+`rules?` | readonly ValidationRule[] |
+`typeInfo?` | *TypeInfo* |
+`options?` | *object* |
+`options.maxErrors?` | *number* |
+
+**Returns:** readonly *GraphQLError*[]

src/server.ts

@@ -9,11 +9,14 @@ import {
   GraphQLSchema,
   ExecutionArgs,
   parse,
-  validate,
+  validate as graphqlValidate,
   getOperationAST,
   GraphQLError,
   SubscriptionArgs,
   ExecutionResult,
+  DocumentNode,
+  ValidationRule,
+  TypeInfo,
 } from 'graphql';
 import { GRAPHQL_TRANSPORT_WS_PROTOCOL } from './protocol';
 import {
@@ -114,6 +117,26 @@ export interface ServerOptions<E = unknown> {
       NonNullable<SubscriptionArgs['rootValue']>
     >;
   };
+  /**
+   * A custom GraphQL validate function allowing you to apply your
+   * own validation rules.
+   *
+   * Returned, non-empty, array of `GraphQLError`s will be communicated
+   * to the client through the `ErrorMessage`. Use an empty array if the
+   * document is valid and no errors have been encountered.
+   *
+   * Will not be used when implementing a custom `onSubscribe`.
+   *
+   * Throwing an error from within this function will close the socket
+   * with the `Error` message in the close event reason.
+   */
+  validate?: (
+    schema: GraphQLSchema,
+    documentAST: DocumentNode,
+    rules?: ReadonlyArray<ValidationRule>,
+    typeInfo?: TypeInfo,
+    options?: { maxErrors?: number },
+  ) => ReadonlyArray<GraphQLError>;
   /**
    * Is the `execute` function from GraphQL which is
    * used to execute the query and mutation operations.
@@ -447,6 +470,7 @@ export function makeServer<E = unknown>(options: ServerOptions<E>): Server<E> {
     schema,
     context,
     roots,
+    validate,
     execute,
     subscribe,
     connectionInitWaitTimeout = 3 * 1000, // 3 seconds
@@ -619,7 +643,7 @@ export function makeServer<E = unknown>(options: ServerOptions<E>): Server<E> {
                     ? await schema(ctx, message, args)
                     : schema,
               };
-              const validationErrors = validate(
+              const validationErrors = (validate ?? graphqlValidate)(
                 execArgs.schema,
                 execArgs.document,
               );

src/tests/server.ts

@@ -93,6 +93,37 @@ it('should use the schema resolved from a promise on subscribe', async (done) =>
   );
 });
 
+it('should use the provided validate function', async () => {
+  const { url } = await startTServer({
+    schema,
+    validate: () => [new GraphQLError('Nothing is valid')],
+  });
+  const client = await createTClient(url, GRAPHQL_TRANSPORT_WS_PROTOCOL);
+  client.ws.send(
+    stringifyMessage<MessageType.ConnectionInit>({
+      type: MessageType.ConnectionInit,
+    }),
+  );
+  await client.waitForMessage(); // ack
+
+  client.ws.send(
+    stringifyMessage<MessageType.Subscribe>({
+      id: '1',
+      type: MessageType.Subscribe,
+      payload: {
+        query: '{ getValue }',
+      },
+    }),
+  );
+  await client.waitForMessage(({ data }) => {
+    expect(parseMessage(data)).toEqual({
+      id: '1',
+      type: MessageType.Error,
+      payload: [{ message: 'Nothing is valid' }],
+    });
+  });
+});
+
 it('should use the provided roots as resolvers', async () => {
   const schema = buildSchema(`
     type Query {