29 building API

构建 API

本节我们将介绍使用 HTTP 请求方法 GET、PUT、POST 和 DELETE 操作数据的 RESTful API。

RESTful API 是一种应用程序接口（API），通过 HTTP 请求来 GET、PUT、POST 和 DELETE 数据。此前我们已经学过 Python、Flask 和 MongoDB。我们将运用所学知识，用 Python Flask 和 MongoDB 开发一个 RESTful API。凡是具备 CRUD（Create、Read、Update、Delete）操作的应用，通常都有 API，用来从数据库创建、获取、更新或删除数据。

浏览器通常只能处理 GET 请求。因此，我们需要一个能帮我们处理所有请求方法（GET、POST、PUT、DELETE）的工具。

API 示例

• Countries API: https://restcountries.eu/rest/v2/all
• Cats breed API: https://api.thecatapi.com/v1/breeds

Postman 是 API 开发中非常常用的工具。若要完成本节内容，需要 下载 Postman。Postman 的替代品是 Insomnia。

API 的结构

API 端点是一个 URL，可用于检索、创建、更新或删除资源。结构大致如下： 示例： https://api.twitter.com/1.1/lists/members.json 返回指定列表的成员。私有列表成员仅当经过身份验证的用户拥有该列表时才会显示。 通常是公司名，后跟版本，再后跟 API 的用途。 方法： HTTP 方法与 URL

该 API 使用以下 HTTP 方法操作对象：

GET        Used for object retrieval
POST       Used for object creation and object actions
PUT        Used for object update
DELETE     Used for object deletion

让我们构建一个收集 30DaysOfPython 学员信息的 API。我们将收集姓名、国家、城市、出生日期、技能和简介。

要实现这个 API，我们将使用：

• Postman
• Python
• Flask
• MongoDB

使用 GET 检索数据

这一步我们先使用虚拟数据，并以 JSON 形式返回。要返回 JSON，将使用 json 模块和 Response 模块。

# let's import the flask

from flask import Flask,  Response
import json
import os

app = Flask(__name__)

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():
    student_list = [
        {
            'name':'Asabeneh',
            'country':'Finland',
            'city':'Helsinki',
            'skills':['HTML', 'CSS','JavaScript','Python']
        },
        {
            'name':'David',
            'country':'UK',
            'city':'London',
            'skills':['Python','MongoDB']
        },
        {
            'name':'John',
            'country':'Sweden',
            'city':'Stockholm',
            'skills':['Java','C#']
        }
    ]
    return Response(json.dumps(student_list), mimetype='application/json')


if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

在浏览器中请求 http://localhost:5000/api/v1.0/students 时，你会看到：

在 Postman 中请求 http://localhost:5000/api/v1.0/students 时，你会看到：

不再显示虚拟数据，我们把 Flask 应用连接到 MongoDB，并从 MongoDB 数据库获取数据。

# let's import the flask

from flask import Flask,  Response
import json
import pymongo
import os

app = Flask(__name__)

#
MONGODB_URI='mongodb+srv://asabeneh:your_password@30daysofpython-twxkr.mongodb.net/test?retryWrites=true&w=majority'
client = pymongo.MongoClient(MONGODB_URI)
db = client['thirty_days_of_python'] # accessing the database

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():

    return Response(json.dumps(student), mimetype='application/json')


if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

连接 Flask 后，我们可以从 thirty_days_of_python 数据库中获取 students 集合的数据。

[
    {
        "_id": {
            "$oid": "5df68a21f106fe2d315bbc8b"
        },
        "name": "Asabeneh",
        "country": "Finland",
        "city": "Helsinki",
        "age": 38
    },
    {
        "_id": {
            "$oid": "5df68a23f106fe2d315bbc8c"
        },
        "name": "David",
        "country": "UK",
        "city": "London",
        "age": 34
    },
    {
        "_id": {
            "$oid": "5df68a23f106fe2d315bbc8e"
        },
        "name": "Sami",
        "country": "Finland",
        "city": "Helsinki",
        "age": 25
    }
]

根据 id 获取文档

我们可以用 id 访问单条文档，下面用 Asabeneh 的 id 访问他。 http://localhost:5000/api/v1.0/students/5df68a21f106fe2d315bbc8b

# let's import the flask

from flask import Flask,  Response
import json
from bson.objectid import ObjectId
import json
from bson.json_util import dumps
import pymongo
import os

app = Flask(__name__)

#
MONGODB_URI='mongodb+srv://asabeneh:your_password@30daysofpython-twxkr.mongodb.net/test?retryWrites=true&w=majority'
client = pymongo.MongoClient(MONGODB_URI)
db = client['thirty_days_of_python'] # accessing the database

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():

    return Response(json.dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students/<id>', methods = ['GET'])
def single_student (id):
    student = db.students.find({'_id':ObjectId(id)})
    return Response(dumps(student), mimetype='application/json')

if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

[
    {
        "_id": {
            "$oid": "5df68a21f106fe2d315bbc8b"
        },
        "name": "Asabeneh",
        "country": "Finland",
        "city": "Helsinki",
        "age": 38
    }
]

使用 POST 创建数据

我们使用 POST 请求方法创建数据。

# let's import the flask

from flask import Flask,  Response
import json
from bson.objectid import ObjectId
import json
from bson.json_util import dumps
import pymongo
from datetime import datetime
import os

app = Flask(__name__)

#
MONGODB_URI='mongodb+srv://asabeneh:your_password@30daysofpython-twxkr.mongodb.net/test?retryWrites=true&w=majority'
client = pymongo.MongoClient(MONGODB_URI)
db = client['thirty_days_of_python'] # accessing the database

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():

    return Response(json.dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students/<id>', methods = ['GET'])
def single_student (id):
    student = db.students.find({'_id':ObjectId(id)})
    return Response(dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students', methods = ['POST'])
def create_student ():
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.insert_one(student)
    return ;
def update_student (id):
if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

使用 PUT 更新

# let's import the flask

from flask import Flask,  Response
import json
from bson.objectid import ObjectId
import json
from bson.json_util import dumps
import pymongo
from datetime import datetime
import os

app = Flask(__name__)

#
MONGODB_URI='mongodb+srv://asabeneh:your_password@30daysofpython-twxkr.mongodb.net/test?retryWrites=true&w=majority'
client = pymongo.MongoClient(MONGODB_URI)
db = client['thirty_days_of_python'] # accessing the database

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():

    return Response(json.dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students/<id>', methods = ['GET'])
def single_student (id):
    student = db.students.find({'_id':ObjectId(id)})
    return Response(dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students', methods = ['POST'])
def create_student ():
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.insert_one(student)
    return
@app.route('/api/v1.0/students/<id>', methods = ['PUT']) # this decorator create the home route
def update_student (id):
    query = {"_id":ObjectId(id)}
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.update_one(query, student)
    # return Response(dumps({"result":"a new student has been created"}), mimetype='application/json')
    return
def update_student (id):
if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

使用 DELETE 删除文档

# let's import the flask

from flask import Flask,  Response
import json
from bson.objectid import ObjectId
import json
from bson.json_util import dumps
import pymongo
from datetime import datetime
import os

app = Flask(__name__)

#
MONGODB_URI='mongodb+srv://asabeneh:your_password@30daysofpython-twxkr.mongodb.net/test?retryWrites=true&w=majority'
client = pymongo.MongoClient(MONGODB_URI)
db = client['thirty_days_of_python'] # accessing the database

@app.route('/api/v1.0/students', methods = ['GET'])
def students ():

    return Response(json.dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students/<id>', methods = ['GET'])
def single_student (id):
    student = db.students.find({'_id':ObjectId(id)})
    return Response(dumps(student), mimetype='application/json')
@app.route('/api/v1.0/students', methods = ['POST'])
def create_student ():
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.insert_one(student)
    return
@app.route('/api/v1.0/students/<id>', methods = ['PUT']) # this decorator create the home route
def update_student (id):
    query = {"_id":ObjectId(id)}
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.update_one(query, student)
    # return Response(dumps({"result":"a new student has been created"}), mimetype='application/json')
    return
@app.route('/api/v1.0/students/<id>', methods = ['PUT']) # this decorator create the home route
def update_student (id):
    query = {"_id":ObjectId(id)}
    name = request.form['name']
    country = request.form['country']
    city = request.form['city']
    skills = request.form['skills'].split(', ')
    bio = request.form['bio']
    birthyear = request.form['birthyear']
    created_at = datetime.now()
    student = {
        'name': name,
        'country': country,
        'city': city,
        'birthyear': birthyear,
        'skills': skills,
        'bio': bio,
        'created_at': created_at

    }
    db.students.update_one(query, student)
    # return Response(dumps({"result":"a new student has been created"}), mimetype='application/json')
    return ;
@app.route('/api/v1.0/students/<id>', methods = ['DELETE'])
def delete_student (id):
    db.students.delete_one({"_id":ObjectId(id)})
    return
if __name__ == '__main__':
    # for deployment
    # to make it work for both production and development
    port = int(os.environ.get("PORT", 5000))
    app.run(debug=True, host='0.0.0.0', port=port)

💻 练习：第 29 天

1. 实现上面的示例，并开发 这个应用。