Использование модели через REST

Обзор

LoopBack модели автоматически имеют стандартный набор HTTP эндпоинтов, который обеспечивает REST APIs операциями CRUD для работы с данными: создание, чтение, обновление и удаление.  Публичные свойства  в model-config.json указывают следует ли использовать REST APIs  в модели, например:

/server/model-config.json

...
"MyModel": {
  "public": true,
  "dataSource": "db"
},
...

Чтоб “скрыть”  REST API модели, просто смените свойство public на false.

REST путь

По умолчанию REST APIs используют множественную форму имени модели; а именно:

• Model.settings.http.path
• Model.settings.plural, if defined in models.json; см Справочник по компоновки проекта для получения более детальной информации.
• Автоматически множественное имя модели (по умолчанию). например, если у вас есть модель - location, по умолчанию она монтируется на  /locations. 

Использование маршрутизатора REST

По умолчанию, базовое приложение использует модель через REST используя loopback.rest маршрутизатор.

Чтобы вручную подключить модель через REST с помощью  loopback.rest маршрутизатор, используйте следующий код, например:

/server/server.js

var app = loopback();
app.use(loopback.rest()); 
// Expose the `Product` model
app.model(Product);

After this, the Product model will have create, read, update, and delete (CRUD) functions working remotely from mobile. At this point, the model is schema-less and the data are not checked.

You can then view generated REST documentation at http://localhost:3000/explorer.

LoopBack provides a number of Built-in models that have REST APIs.  See Built-in models REST API for more information.

Формат запроса

For POST and PUT requests, the request body can be JSON, XML or urlencoded format, with the Content-Type header set to application/json, application/xml, or application/x-www-form-urlencoded. The Accept header indicates its preference for the response format.

The following is an example HTTP request to create a new note:

POST / api / Notes HTTP / 1.1
Host: localhost: 3000
Connection: keep - alive
Content - Length: 61
Accept: application / json
Content - Type: application / json  {
  "title": "MyNote",
  "content": "This is my first note"
}

Passing JSON object or array using HTTP query string

Some REST APIs take a JSON object or array from the query string. LoopBack supports two styles to encode the object/array value as query parameters.

• The syntax from node-querystring (qs)
• Stringified JSON

For example,

http: //localhost:3000/api/users?filter[where][username]=john&filter[where][email]=callback@strongloop.com
  http: //localhost:3000/api/users?filter={"where":{"username":"john","email":"callback@strongloop.com"}}

The table below illustrates how to encode the JSON object/array can be encoded in different styles:

{ where: 
  { username: 'john' }, 
    email: 'callback@strongloop.com' } }

?filter[where][username]=john
&filter[where][email]=callback@strongloop.com

?filter={"where":
  {"username":"john",
   "email":"callback@strongloop.com"}}

{ where: 
  { username: {inq: ['john', 'mary']} } }

?filter[where][username][inq][0]=john
&filter[where][username][inq][1]=mary

?filter={"where":
  {"username":{"inq":["john","mary"]}}}

{ include: ['a', 'b'] }

?filter[include]=a&filter[include]=b

?filter={"include":["a","b"]}

Формат ответа

The response format for all requests is typically a JSON object/array or XML in the body and a set of headers. Some responses have an empty body. For example,

HTTP / 1.1 200 OK
Access - Control - Allow - Origin: http: //localhost:3000
  Access - Control - Allow - Credentials: true
Content - Type: application / json;
charset = utf - 8
Content - Length: 59
Vary: Accept - Encoding
Date: Fri, 24 Oct 2014 18: 02: 34 GMT
Connection: keep - alive  {
  "title": "MyNote",
  "content": "This is my first note",
  "id": 1
}

The HTTP status code indicates whether a request succeeded:

• Status code 2xx indicates success
• Status code 4xx indicates request related issues.
• Status code 5xx indicates server-side problems

The response for an error is in the following JSON format:

• message: String error message.
• stack: String stack trace.
• statusCode: Integer HTTP status code.

For example,

{
  "error": {
    "message": "could not find a model with id 1",
    "stack": "Error: could not find a model with id 1\n ...",
    "statusCode": 404
  }
}

Отключение API Explorer

LoopBack API Explorer полезен, когда вы разрабатываете свое приложение, но с точки зрения безопасности вы навряд ли заточите использовать его в продакшене.  Для отключения API Explorer полностью, если вы создовали ваше приложение с помощью Генератора приложения, просто удалите или переименуйте  /server/boot/explorer.js. 

Предопределенные удаленные методы

By default, for a model backed by a data source that supports it, LoopBack exposes a REST API that provides all the standard create, read, update, and delete (CRUD) operations.

As an example, consider a simple model called Location (that provides business locations) to illustrate the REST API exposed by LoopBack.  LoopBack automatically creates the following endpoints:

The above API follows the standard LoopBack model REST API that most built-in models extend.  See PersistedModel REST API for more details.

Обнаружение модели

To expose a model over REST, set the public property to true in /server/model-config.json:

...
"Role": {
  "dataSource": "db",
  "public": false
},
...

Hiding methods and REST endpoints

If you don’t want to expose certain CRUD operations, you can easily hide them by calling disableRemoteMethod() on the model. For example, following the previous example, by convention custom model code would go in the file common/models/location.js.  You would add the following lines to “hide” one of the predefined remote methods:

common/models/location.js

var isStatic = true;
MyModel.disableRemoteMethod('deleteById', isStatic);

Now the deleteById() operation and the corresponding REST endpoint will not be publicly available.

For a method on the prototype object, such as updateAttributes():

common/models/location.js

var isStatic = false;
MyModel.disableRemoteMethod('updateAttributes', isStatic);

Hiding endpoints for related models

To disable a REST endpoints for related model methods, use disableRemoteMethod().

For example, if there are post and tag models, where a post hasMany tags, add the following code to /common/models/post.js to disable the remote methods for the related model and the corresponding REST endpoints: 

common/models/model.js

module.exports = function(Post) {
  Post.disableRemoteMethod('__get__tags', false);
  Post.disableRemoteMethod('__create__tags', false);
  Post.disableRemoteMethod('__delete__tags', false);
};