Flask-RESTful关于响应

雨点打透心脏的1/2处 2022-12-11 13:48 112阅读 0赞

# 关于响应处理 #

## 1 序列化数据 ##

Flask-RESTful 提供了marshal工具，用来帮助我们将数据序列化为特定格式的字典数据，以便作为视图的返回值。

from flask_restful import Resource, fields, marshal_with
    
    resource_fields = { 
        'name': fields.String,
        'address': fields.String,
        'user_id': fields.Integer
    }
    
    class Todo(Resource):
        @marshal_with(resource_fields, envelope='resource')
        def get(self, **kwargs):
            return db_get_todo()

也可以不使用装饰器的方式

class Todo(Resource):
        def get(self, **kwargs):
            data = db_get_todo()
            return marshal(data, resource_fields)

#### 示例 ####

# 用来模拟要返回的数据对象的类
    class User(object):
        def __init__(self, user_id, name, age):
            self.user_id = user_id
            self.name = name
            self.age = age
    
    resoure_fields = { 
            'user_id': fields.Integer,
            'name': fields.String
        }
    
    class Demo1Resource(Resource):
        @marshal_with(resoure_fields, envelope='data1')
        def get(self):
            user = User(1, 'itcast', 12)
            return user
    
    class Demo2Resource(Resource):
        def get(self):
            user = User(1, 'itcast', 12)
            return marshal(user, resoure_fields, envelope='data2')

## 2 定制返回的JSON格式 ##

### 需求 ###

想要接口返回的JSON数据具有如下统一的格式

{ "message": "描述信息", "data": { 要返回的具体数据}}

在接口处理正常的情况下， message返回ok即可，但是若想每个接口正确返回时省略message字段

class DemoResource(Resource):
        def get(self):
            return { 'user_id':1, 'name': 'itcast'}

对于诸如此类的接口，能否在某处统一格式化成上述需求格式？

{ "message": "OK", "data": { 'user_id':1, 'name': 'itcast'}}

### 解决 ###

**Flask-RESTful的Api对象提供了一个`representation`的装饰器，允许定制返回数据的呈现格式**

api = Api(app)
    
    @api.representation('application/json')
    def handle_json(data, code, headers):
        # TODO 此处添加自定义处理
        return resp

Flask-RESTful原始对于json的格式处理方式如下：

代码出处：`flask_restful.representations.json`

from flask import make_response, current_app
    from flask_restful.utils import PY3
    from json import dumps
    
    
    def output_json(data, code, headers=None):
        """Makes a Flask response with a JSON encoded body"""
    
        settings = current_app.config.get('RESTFUL_JSON', { })
    
        # If we're in debug mode, and the indent is not set, we set it to a
        # reasonable value here. Note that this won't override any existing value
        # that was set. We also set the "sort_keys" value.
        if current_app.debug:
            settings.setdefault('indent', 4)
            settings.setdefault('sort_keys', not PY3)
    
        # always end the json dumps with a new line
        # see https://github.com/mitsuhiko/flask/pull/1262
        dumped = dumps(data, **settings) + "\n"
    
        resp = make_response(dumped, code)
        resp.headers.extend(headers or { })
        return resp

为满足需求，做如下改动即可

@api.representation('application/json')
    def output_json(data, code, headers=None):
        """Makes a Flask response with a JSON encoded body"""
    
        # 此处为自己添加***************
        if 'message' not in data:
            data = { 
                'message': 'OK',
                'data': data
            }
        # **************************
    
        settings = current_app.config.get('RESTFUL_JSON', { })
    
        # If we're in debug mode, and the indent is not set, we set it to a
        # reasonable value here. Note that this won't override any existing value
        # that was set. We also set the "sort_keys" value.
        if current_app.debug:
            settings.setdefault('indent', 4)
            settings.setdefault('sort_keys', not PY3)
    
        # always end the json dumps with a new line
        # see https://github.com/mitsuhiko/flask/pull/1262
        dumped = dumps(data, **settings) + "\n"
    
        resp = make_response(dumped, code)
        resp.headers.extend(headers or { })
        return resp