Add "app.api()" method for registering routes

packages/core/src/application.ts

@@ -3,18 +3,15 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
+import * as assert from 'assert';
 import {
   Binding,
   Context,
   Constructor,
   Provider,
   inject,
 } from '@loopback/context';
-import {
-  OpenApiSpec,
-  Route,
-  ParsedRequest,
-} from '.';
+import {OpenApiSpec, Route, ParsedRequest, OperationObject} from '.';
 import {ServerRequest, ServerResponse} from 'http';
 import {Component, mountComponent} from './component';
 import {getApiSpec} from './router/metadata';
@@ -139,6 +136,21 @@ export class Application extends Context {
     return this.bind(`routes.${route.verb} ${route.path}`).to(route);
   }
 
+  api(spec: OpenApiSpec) {
+    for (const path in spec.paths) {
+      for (const verb in spec.paths[path]) {
+        const routeSpec: OperationObject = spec.paths[path][verb];
+        const handler = routeSpec['x-operation'];
+        assert(
+          typeof handler === 'function',
+          `"x-operation" field of "${verb} ${path}" must be a function`);
+
+        const route = new Route(verb, path, routeSpec, handler);
+        this.route(route);
+      }
+    }
+  }
+
   protected _logError(
     err: Error,
     statusCode: number,

packages/core/test/acceptance/routing/routing.acceptance.ts

@@ -221,6 +221,25 @@ describe('Routing', () => {
     await client.get('/greet?name=world').expect(200, 'hello world');
   });
 
+  it('supports routes declared via API specification', async () => {
+    const app = givenAnApplication();
+
+    function greet(name: string) {
+      return `hello ${name}`;
+    }
+
+    const spec = anOpenApiSpec()
+      .withOperation('get', '/greet', anOperationSpec()
+        .withParameter({name: 'name', in: 'query', type: 'string'})
+        .withExtension('x-operation', greet))
+      .build();
+
+    app.api(spec);
+
+    const client = await whenIMakeRequestTo(app);
+    await client.get('/greet?name=world').expect(200, 'hello world');
+  });
+
   /* ===== HELPERS ===== */
 
   function givenAnApplication() {

packages/openapi-spec-builder/src/openapi-spec-builder.ts

@@ -4,6 +4,7 @@
 // License text available at https://opensource.org/licenses/MIT
 
 import {
+  ExtensionValue,
   OpenApiSpec,
   OperationObject,
   ResponseObject,
@@ -78,6 +79,17 @@ export class OpenApiSpecBuilder {
         .withStringResponse(200));
   }
 
+  /**
+   * Add a custom (extension) property to the operation definition.
+   *
+   * @param key The property name starting with "x-".
+   * @param value The property value.
+   */
+  withExtension(key: string, value: ExtensionValue): this {
+    this._spec[key] = value;
+    return this;
+  }
+
   /**
    * Build the OpenApiSpec object.
    */
@@ -132,7 +144,17 @@ export class OperationSpecBuilder {
    * @param name The name of the controller method implementing this operation.
    */
   withOperationName(name: string): this {
-    this._spec['x-operation-name'] = name;
+    return this.withExtension('x-operation-name', name);
+  }
+
+  /**
+   * Add a custom (extension) property to the operation definition.
+   *
+   * @param key The property name starting with "x-".
+   * @param value The property value.
+   */
+  withExtension(key: string, value: ExtensionValue): this {
+    this._spec[key] = value;
     return this;
   }