使用python3和flask构建RESTful API(接口测试服务)

引言

构建RESTful API貌似是开发的工作，和测试有和关系？

其实测试开发需要构建RESTful API的场景很多。比如测试Android应用，一般的接口测试只考虑了服务器端，至于客户端在网络异常或者服务端异常时如何反应，多数天朝的测试人员是没有考虑到的。客户端在对这些异常处理不够充分的时候，会出现崩溃等各种莫名其妙的问题。

为此一些走在前沿的测试人员会自己写一些RESTful API， 把服务端的域名劫持到自己的API，故意返回各种异常，看客户端的稳定性。

另外测试开发的测试工具需要和其他系统对接等场景也经常需要API。

术语

REST： REpresentational State Transfer

目标

• 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

工程目录

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

requirements.txt的内容如下：

flask
flask_restful
flask_script
flask_migrate
marshmallow
flask_sqlalchemy
flask_marshmallow
marshmallow-sqlalchemy
psycopg2

• flask – Python的微框架

• flask_restful – 这是Flask的扩展，可快速构建REST API。

• flask_script – 提供了在Flask中编写外部脚本的支持。

• flask_migrate – 使用Alembic的Flask应用进行SQLAlchemy数据库迁移。

• marshmallow – ORM/ODM/框架无关的库，用于复杂数据类型（如对象）和Python数据类型转换。

• flask_sqlalchemy – Flask扩展，增加了对SQLAlchemy的支持。

• flask_marshmallow – 这是Flask和marshmallow的中间层。

• marshmallow-sqlalchemy – 这是sqlalchemy和marshmallow的中间层。

• psycopg – Python的PostgreSQL API。

安装依赖

# pip3 install -r requirements.txt

安装配置PostgreSQL

这里以 Ubuntu 16.04为例：

# sudo apt-get update && sudo apt-get upgrade
# apt-get install postgresql postgresql-contrib
# su - postgres
$ createdb api
$ createuser andrew --pwprompt #创建用户
$ psql -d api -c "ALTER USER andrew WITH PASSWORD 'api';"

参考资料：

https://linode.com/docs/databases/postgresql/how-to-install-postgresql-on-ubuntu-16-04/

https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-14-04

配置

# -*- 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')

快速入门

app.py

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

#!/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

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)

启动服务

$ 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

用浏览器访问： http://127.0.0.1:5000/api/Hello

{
    "hello": "world"
}

接入数据库

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',), nullable=False)
    category = db.relationship('Category', backref=db.backref('comments', ))

    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

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()

数据迁移

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

修改Category.py 和Comment.py， 完整代码

测试

可以使用curl，比如：

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：