docs(lb4): scaffolding a CRUD controller (#583)

* docs(lb4): scaffolding a REST Controller with CRUD

* docs(lb4): Update empty controller example

pages/en/lb4/Controller-generator.md

@@ -31,8 +31,98 @@ If provided, the tool will use that as the default when it prompts for the name.
 
 The tool will prompt you for:
 
-- Name of the controller. If the name had been supplied from the command line, the prompt is skipped and the controller is built with the name from the command-line argument.
+- Name of the controller. If the name had been supplied from the command line,
+the prompt is skipped and the controller is built with the name from the
+command-line argument.
+- Type of the controller. You can select from the following types:
+  * **Empty Controller** - An empty controller definition
+  * **Basic CRUD Controller** - A controller wired up to a model and repository
+  definition, with pre-defined CRUD methods.
 
-### Output
+#### Empty Controller
+If you select the Empty Controller, it will generate a nearly-empty template
+based on the given name:
 
-The tool will create a new file as <code>/src/controllers/<i>controller-name</i>.controller.ts</code>. The file will contain an empty constructor and common package imports that can be uncommented.
+```ts
+// Uncomment these imports to begin using these cool features!
+
+// import {inject} from '@loopback/context';
+
+export class FooController {
+  constructor() {}
+}
+```
+
+#### REST Controller with CRUD Methods
+If you select the REST Controller with CRUD Methods type, you will then be asked
+to select:
+- The model to use for the CRUD function definitions
+- The repository for this model that provides datasource connectivity
+
+{% include warning.html content=
+"
+If you do not have a model and repository to select, then you will
+receive an error!
+" lang=page.lang %}
+
+Here's an example of what the template will produce given a `Todo` model and
+a `TodoRepository`:
+```ts
+import {Filter, Where} from '@loopback/repository';
+import {post, param, get, put, patch, del} from '@loopback/openapi-v2';
+import {inject} from '@loopback/context';
+import {Todo} from '../models';
+import {TodoRepository} from '../repositories';
+
+export class TodoController {
+
+  constructor(
+    @inject('repositories.TodoRepository')
+    public todoRepository : TodoRepository,
+  ) {}
+
+  @post('/todo')
+  async create(@param.body('obj') obj: Todo)
+    : Promise<Todo> {
+    return await this.todoRepository.create(obj);
+  }
+
+  @get('/todo/count')
+  async count(@param.query.string('where') where: Where) : Promise<number> {
+    return await this.todoRepository.count(where);
+  }
+
+  @get('/todo')
+  async find(@param.query.string('filter') filter: Filter)
+    : Promise<Todo[]> {
+      return await this.todoRepository.find(filter);
+  }
+
+  @patch('/todo')
+  async updateAll(@param.query.string('where') where: Where,
+    @param.body('obj') obj: Todo) : Promise<number> {
+      return await this.todoRepository.updateAll(where, obj);
+  }
+
+  @del('/todo')
+  async deleteAll(@param.query.string('where') where: Where) : Promise<number> {
+    return await this.todoRepository.deleteAll(where);
+  }
+
+  @get('/todo/{id}')
+  async findById(@param.path.number('id') id: number) : Promise<Todo> {
+    return await this.todoRepository.findById(id);
+  }
+
+  @patch('/todo/{id}')
+  async updateById(@param.path.number('id') id: number, @param.body('obj')
+   obj: Todo) : Promise<boolean> {
+    return await this.todoRepository.updateById(id, obj);
+  }
+
+  @del('/todo/{id}')
+  async deleteById(@param.path.number('id') id: number) : Promise<boolean> {
+    return await this.todoRepository.deleteById(id);
+  }
+}
+```