feat(fastify): add decorator for custom schema

Add an ability to attach json schema to request with a RequestSchema decorator

Author: piotrfrankowski

packages/platform-fastify/adapters/fastify-adapter.ts

@@ -53,6 +53,7 @@ import { parse as querystringParse } from 'fast-querystring';
 import {
   FASTIFY_ROUTE_CONFIG_METADATA,
   FASTIFY_ROUTE_CONSTRAINTS_METADATA,
+  FASTIFY_ROUTE_SCHEMA_METADATA,
 } from '../constants';
 import { NestFastifyBodyParserOptions } from '../interfaces';
 import {
@@ -752,9 +753,14 @@ export class FastifyAdapter<
       handlerRef,
     );
 
+    const routeSchema = Reflect.getMetadata(
+      FASTIFY_ROUTE_SCHEMA_METADATA,
+      handlerRef,
+    );
+
     const hasConfig = !isUndefined(routeConfig);
     const hasConstraints = !isUndefined(routeConstraints);
-
+    const hasSchema = !isUndefined(routeSchema);
     const routeToInject: RouteOptions<TServer, TRawRequest, TRawResponse> &
       RouteShorthandOptions = {
       method: routerMethodKey,
@@ -766,7 +772,7 @@ export class FastifyAdapter<
       this.instance.addHttpMethod(routerMethodKey, { hasBody: true });
     }
 
-    if (isVersioned || hasConstraints || hasConfig) {
+    if (isVersioned || hasConstraints || hasConfig || hasSchema) {
       const isPathAndRouteTuple = args.length === 2;
       if (isPathAndRouteTuple) {
         const constraints = {
@@ -783,6 +789,9 @@ export class FastifyAdapter<
               ...routeConfig,
             },
           }),
+          ...(hasSchema && {
+            schema: routeSchema,
+          }),
         };
 
         const routeToInjectWithOptions = { ...routeToInject, ...options };

packages/platform-fastify/constants.ts

@@ -1,3 +1,4 @@
 export const FASTIFY_ROUTE_CONFIG_METADATA = '__fastify_route_config__';
 export const FASTIFY_ROUTE_CONSTRAINTS_METADATA =
   '__fastify_route_constraints__';
+export const FASTIFY_ROUTE_SCHEMA_METADATA = '__fastify_route_schema__';

packages/platform-fastify/decorators/index.ts

@@ -1,2 +1,3 @@
 export * from './route-config.decorator';
 export * from './route-constraints.decorator';
+export * from './route-schema.decorator';

packages/platform-fastify/decorators/route-schema.decorator.ts

@@ -0,0 +1,15 @@
+import { SetMetadata } from '@nestjs/common';
+import { FASTIFY_ROUTE_SCHEMA_METADATA } from '../constants';
+import { FastifySchema } from 'fastify';
+
+/**
+ * @publicApi
+ * Allows setting the schema for the route. Schema is an object that can contain the following properties:
+ * - body: JsonSchema
+ * - querystring or query: JsonSchema
+ * - params: JsonSchema
+ * - response: Record<HttpStatusCode, JsonSchema>
+ * @param schema See {@link https://fastify.dev/docs/latest/Reference/Routes/#routes-options}
+ */
+export const RouteSchema = (schema: FastifySchema) =>
+  SetMetadata(FASTIFY_ROUTE_SCHEMA_METADATA, schema);

packages/platform-fastify/test/decorators/router-schema.decorator.spec.ts

@@ -0,0 +1,17 @@
+import { expect } from 'chai';
+import { FASTIFY_ROUTE_SCHEMA_METADATA } from '../../constants';
+import { RouteSchema } from '../../decorators/route-schema.decorator';
+
+describe('@RouteSchema', () => {
+  const routeSchema = { body: 'testValue' };
+  class Test {
+    config;
+    @RouteSchema(routeSchema)
+    public static test() {}
+  }
+
+  it('should enhance method with expected fastify route schema', () => {
+    const path = Reflect.getMetadata(FASTIFY_ROUTE_SCHEMA_METADATA, Test.test);
+    expect(path).to.be.eql(routeSchema);
+  });
+});