Python编程在flask中模拟进行Restful的CRUD操作

这篇文章中我们将通过对HelloWorld的message进行操作，介绍一下如何使用flask进行Restful的CRUD。

概要信息

事前准备：flask

liumiaocn:flask liumiao$ which flask
/usr/local/bin/flask
liumiaocn:flask liumiao$ flask --version
Flask 1.0.2
Python 2.7.10 (default, Jul 15 2017, 17:16:57)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.31)]
liumiaocn:flask liumiao$

代码示例：HTTP谓词（GET）

就像angular的插值表达式在模版中的作用一样，在flask中也可以一样使用，如果不熟悉angular的插值表达式的话也不要紧，看完下面的例子，基本上就会有一个大致的印象。

代码示例

liumiaocn:flask liumiao$ cat flask_4.py
#!/usr/bin/python
from flask import Flask
from flask import render_template
app = Flask(__name__)
greeting_messages=["Hello World", "Hello Python"]
@app.route("/api/messages",methods=['GET'])
def get_messages():
  return render_template("resttest.html",messages=greeting_messages)
if __name__ == "__main__":
  app.debug=True
  app.run(host='0.0.0.0',port=7000)
liumiaocn:flask liumiao$

模版文件

liumiaocn:flask liumiao$ cat templates/resttest.html
<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <title>Hello Restful</title>
</head>
<body>
    {% for message in messages %}
 <h1>{{ message }}</h1>
    {% endfor %}
</body>
</html>
liumiaocn:flask liumiao$

代码解析：app.route中指定了HTTP谓词GET，缺省GET可以省略，如果一个方法对应多个谓词动作，通过request.method来分离时，可以写成methods=[‘GET','POST']的形式

执行&确认

liumiaocn:flask liumiao$ ./flask_4.py
 * Serving Flask app "flask_4" (lazy loading)
 * Environment: production
  WARNING: Do not use the development server in a production environment.
  Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://0.0.0.0:7000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 131-533-062

页面确认

代码示例：HTTP谓词（DELETE|PUT|POST）

liumiaocn:flask liumiao$ cat flask_4.py
#!/usr/bin/python
from flask import Flask
from flask import render_template
from flask import request
import json
app = Flask(__name__)
greeting_messages=["Hello World", "Hello Python"]
#HTTP: GET: Retrieve operation
@app.route("/api/messages",methods=['GET'])
def get_messages():
  return render_template("resttest.html",messages=greeting_messages)
#HTTP: DELETE: Delete operation
@app.route("/api/messages/<messageid>",methods=['DELETE'])
def delete_message(messageid):
  global greeting_messages
  del greeting_messages[int(messageid)]
  return render_template("resttest.html",messages=greeting_messages)
#HTTP: PUT: Update operation
#HTTP: POST: Create operation
@app.route("/api/messages/<messageid>",methods=['PUT','POST'])
def update_message(messageid):
  global greeting_message
  msg_info=json.loads(request.get_data(True,True,False))
  #msg_info=request.args.get('message_info')
  #msg_info=request.form.get('message_info','default value')
  #msg_info=request.values.get('message_info','hello...')
  greeting_messages.append("Hello " + msg_info["message_info"])
  return render_template("resttest.html",messages=greeting_messages)
if __name__ == "__main__":
  app.debug=True
  app.run(host='0.0.0.0',port=7000)
liumiaocn:flask liumiao$

执行&结果确认

执行日志

liumiaocn:flask liumiao$ ./flask_4.py
 * Serving Flask app "flask_4" (lazy loading)
 * Environment: production
  WARNING: Do not use the development server in a production environment.
  Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://0.0.0.0:7000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 131-533-062

结果确认：Delete

liumiaocn:flask liumiao$ curl -X DELETE http://localhost:7000/api/messages/1
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Hello Restful</title>
</head>
<body>
  <h1>Hello World</h1>
</body>
</html>liumiaocn:flask liumiao$

可以看到执行一次DELETE之后，两条消息现在只剩下一条消息了，接下来使用POST添加再添加一条

liumiaocn:flask liumiao$ curl -X POST -d '{"message_info":"LiuMiaoPost"}' http://localhost:7000/api/messages/3
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Hello Restful</title>
</head>
<body>
  <h1>Hello World</h1>
  <h1>Hello LiuMiaoPost</h1>
</body>
</html>liumiaocn:flask liumiao$

再执行一次PUT操作

liumiaocn:flask liumiao$ curl -X PUT -d '{"message_info":"LiuMiaoPut"}' http://localhost:7000/api/messages/4
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Hello Restful</title>
</head>
<body>
  <h1>Hello World</h1>
  <h1>Hello LiuMiaoPost</h1>
  <h1>Hello LiuMiaoPut</h1>
</body>
</html>liumiaocn:flask liumiao$

小结

这篇文章中，使用最简单的方式在flask中模拟了一下如何进行Restful的CRUD操作，当然，实际的做法有很多种，在接下来的文章中还会介绍另外一种非常常见的轮子flask-restful.

总结

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