[雪峰磁針石部落格]使用python3和flask構建RESTfulAPI(介面測試服務)

引言

構建RESTful API貌似是開發的工作，和測試有和關係？

其實測試開發需要構建RESTful API的場景很多。比如測試Android應用，一般的介面測試只考慮了伺服器端，至於客戶端在網路異常或者服務端異常時如何反應，多數天朝的測試人員是沒有考慮到的。客戶端在對這些異常處理不夠充分的時候，會出現崩潰等各種莫名其妙的問題。

為此一些走在前沿的測試人員會自己寫一些RESTful API，把服務端的域名劫持到自己的API，故意返回各種異常，看客戶端的穩定性。

另外測試開發的測試工具需要和其他系統對接等場景也經常需要API。

參考資料

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How to Build RESTful APIs with Python and Flask

術語

REST： REpresentational State Transfer

目標

GET – /api/Category – Retrieve all categories
POST – /api/Category – Add a new category
PUT – /api/Category – Update a category
DELETE – /api/Category – Delete a category
GET – /api/Comment – Retrieve all the stored comments
POST – /api/Comment – Add new comment

要求

python3.*
PostgreSQL

工程目錄

#!python
project/
├── app.py
├── config.py
├── migrate.py
├── Model.py
├── requirements.txt
├── resources
│   └── Hello.py
│   └── Comment.py
│   └── Category.py
└── run.py

requirements.txt的內容如下：

#!python

flask
flask_restful
flask_script
flask_migrate
marshmallow
flask_sqlalchemy
flask_marshmallow
marshmallow-sqlalchemy
psycopg2

flask – Python的微框架
flask_restful – 這是Flask的擴充套件，可快速構建REST API。
flask_script – 提供了在Flask中編寫外部指令碼的支援。
flask_migrate – 使用Alembic的Flask應用進行SQLAlchemy資料庫遷移。
marshmallow – ORM/ODM/框架無關的庫，用於複雜資料型別（如物件）和Python資料型別轉換。
flask_sqlalchemy – Flask擴充套件，增加了對SQLAlchemy的支援。
flask_marshmallow – 這是Flask和marshmallow的中間層。
marshmallow-sqlalchemy – 這是sqlalchemy和marshmallow的中間層。
psycopg – Python的PostgreSQL API。

安裝依賴

#!python

# pip3 install -r requirements.txt

安裝配置PostgreSQL

這裡以 Ubuntu 16.04為例：

#!python

# sudo apt-get update && sudo apt-get upgrade
# apt-get install postgresql postgresql-contrib
# su - postgres
$ createdb api
$ createuser andrew --pwprompt #建立使用者
$ psql -d api -c "ALTER USER andrew WITH PASSWORD `api`;"

參考資料：

How to Install PostgreSQL on Ubuntu 16.04

How To Install and Use PostgreSQL on Ubuntu 14.04

配置

#!python

# -*- coding: utf-8 -*-
# Author:    xurongzhong#126.com wechat:pythontesting qq:37391319
# CreateDate: 2018-1-10

from flask import Blueprint
from flask_restful import Api
from resources.Hello import Hello
from resources.Category import CategoryResource
from resources.Comment import CommentResource


api_bp = Blueprint(`api`, __name__)
api = Api(api_bp)

# Routes
api.add_resource(Hello, `/Hello`)
api.add_resource(CategoryResource, `/Category`)
api.add_resource(CommentResource, `/Comment`)

快速入門

app.py

#!python

from flask import Blueprint
from flask_restful import Api
from resources.Hello import Hello

api_bp = Blueprint(`api`, __name__)
api = Api(api_bp)

# Route
api.add_resource(Hello, `/Hello`)

resource/Hello.py

#!python

#!/usr/bin/python
# -*- coding: utf-8 -*-
# Author:    xurongzhong#126.com wechat:pythontesting qq:37391319
# CreateDate: 2018-1-10

from flask_restful import Resource


class Hello(Resource):
    def get(self):
        return {"message": "Hello, World!"}

    def post(self):
        return {"message": "Hello, World!"}

run.py

#!python

from flask import Flask


def create_app(config_filename):
    app = Flask(__name__)
    app.config.from_object(config_filename)

    from app import api_bp
    app.register_blueprint(api_bp, url_prefix=`/api`)

    return app


if __name__ == "__main__":
    app = create_app("config")
    app.run(debug=True)

啟動服務

#!python

$ python3 run.py
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 136-695-873

用瀏覽器訪問： http://127.0.0.1:5000/api/Hello

#!python

{
    "hello": "world"
}

接入資料庫

#!python

from flask import Flask
from marshmallow import Schema, fields, pre_load, validate
from flask_marshmallow import Marshmallow
from flask_sqlalchemy import SQLAlchemy


ma = Marshmallow()
db = SQLAlchemy()


class Comment(db.Model):
    __tablename__ = `comments`
    id = db.Column(db.Integer, primary_key=True)
    comment = db.Column(db.String(250), nullable=False)
    creation_date = db.Column(db.TIMESTAMP, server_default=db.func.current_timestamp(), nullable=False)
    category_id = db.Column(db.Integer, db.ForeignKey(`categories.id`, ondelete=`CASCADE`), nullable=False)
    category = db.relationship(`Category`, backref=db.backref(`comments`, lazy=`dynamic` ))

    def __init__(self, comment, category_id):
        self.comment = comment
        self.category_id = category_id


class Category(db.Model):
    __tablename__ = `categories`
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(150), unique=True, nullable=False)

    def __init__(self, name):
        self.name = name


class CategorySchema(ma.Schema):
    id = fields.Integer()
    name = fields.String(required=True)


class CommentSchema(ma.Schema):
    id = fields.Integer(dump_only=True)
    category_id = fields.Integer(required=True)
    comment = fields.String(required=True, validate=validate.Length(1))
    creation_date = fields.DateTime()

migrate.py

#!python

from flask_script import Manager
from flask_migrate import Migrate, MigrateCommand
from Model import db
from run import create_app

app = create_app(`config`)

migrate = Migrate(app, db)
manager = Manager(app)
manager.add_command(`db`, MigrateCommand)


if __name__ == `__main__`:
    manager.run()

資料遷移

#!python

$ python3 migrate.py db init
$ python3 migrate.py db migrate
$ python migrate.py db upgrade

修改Category.py 和Comment.py，完整程式碼

測試

可以使用curl，比如：

#!python

curl http://127.0.0.1:5000/api/Category --data `{"name":"test5","id":5}` -H "Content-Type: application/json"

也可以在chrome中使用postman：

how_to_build_restful_apis_using_flask_creating_categories.png

how_to_build_restful_apis_using_flask_listing_categories.png

how_to_build_restful_apis_using_flask_creating_comment.png

how_to_build_restful_apis_in_flask_listing_comments.png