The book continues from the above Python Flask tutorial learning 01
Article directory
Flask Tutorial
Flask session
Unlike Cookie, Session (session) data is stored on the server. A session is the time interval during which a client logs on to a server and logs off from the server. Data that needs to be saved for this session is stored in a temporary directory on the server.
from flask import render_template
from flask import make_response
from flask import Flask,session,redirect,url_for,escape,request
app=Flask(__name__)
#为每个客户端的会话分配会话ID。
#会话数据存储在cookie的顶部，服务器以加密方式对其进行签名。
#对于此加密，Flask应用程序需要一个定义的SECRET_KEY。（随便写）
app.secret_key='fkdjsafjdkfdlkjfadskjfadskljdsfklj'
@app.route('/')
def index():
if 'username' in session:
username=session['username']
return '登录用户名是:'+username+'<br>'+\
"<b><a href='/logout'>点击这里注销</a></b>"
return "您暂未登录,<br><a href='/login'></b>"+\
"点击这里登录</b></a>"
@app.route('/login',methods=['GET','POST'])
def login():
if request.method=='POST':
#设置会话变量
session['username']=request.form['username']
return redirect(url_for('index'))
return '''
<form action="" method="post">
<p><input type="text" name="username"/></p>
<p><input type="submit" value="登录"/></p>
</form>
'''
@app.route('/logout')
def logout():
#释放会话变量
session.pop('username',None)
return redirect(url_for('index'))
if __name__ == '__main__':
app.run(debug=True)
http://127.0.0.1:5000/
Flask message flash
from flask import Flask, flash, redirect, render_template, request, url_for
app = Flask(__name__)
app.secret_key = 'random string'
@app.route('/')
def index():
return render_template('index.html')
@app.route('/login', methods = ['GET', 'POST'])
def login():
error = None
if request.method == 'POST':
if request.form['username'] != 'admin' or request.form['password'] != 'admin':
error = 'Invalid username or password. Please try again!'
#如果登录成功，则会在索引模板上刷新成功消息。
else:
'''
flash(message, category)
message 参数是要闪现的实际消息。
category 参数是可选的。它可以是“error”，“info”或“warning”。
'''
flash('You were successfully logged in')
return redirect(url_for('index'))
#如果出现错误，则会重新显示登录模板，并显示错误消息。
return render_template('login.html', error = error)
if __name__ == '__main__':
app.run(debug=True)
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Login</title>
</head>
<body>
<form method = "post" action = "http://localhost:5000/login">
<table>
<tr>
<td>Username</td>
<td><input type = 'username' name = 'username'></td>
</tr>
<tr>
<td>Password</td>
<td><input type = 'password' name = 'password'></td>
</tr>
<tr>
<td><input type = "submit" value = "Submit"></td>
</tr>
</table>
</form>
{% if error %}
<p><strong>Error</strong>: {
{ error }}</p>
{% endif %}
</body>
</html>
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Index</title>
</head>
<body>
<!--
为了从会话中删除消息，模板调用 get_flashed_messages(with_categories, category_filter)。
两个参数都是可选的。
如果接收到的消息具有类别，
则第一个参数是元组。第二个参数仅用于显示特定消息。
-->
{% with messages = get_flashed_messages() %}
{% if messages %}
{% for message in messages %}
<p>{
{ message }}</p>
{% endfor %}
{% endif %}
{% endwith %}
<h3>Welcome!</h3>
<a href = "{
{ url_for('login') }}">login</a>
</body>
</html>
Click the login link (the user name and password are set in the program, the example is admin) and it will be
displayed after submission
Flask file upload
Create a new folder uploadto save the successfully uploaded files
from flask import Flask,render_template,request
'''
目标文件的名称可以是硬编码的，
也可以从 request.files[file] 对象的 filename 属性中获取。
但是，建议使用 secure_filename() 函数获取它的安全版本。
'''
from werkzeug.utils import secure_filename
import os
app=Flask(__name__)
#定义上传文件夹的路径
#app.config['MAX_CONTENT_LENGTH'] 指定要上传的文件的最大大小(以字节为单位)
app.config['UPLOAD_FOLDER']='upload/'
@app.route('/upload')
def upload_file():
return render_template('upload.html')
@app.route('/uploader',methods=['GET','POST'])
def uploader():
if request.method=='POST':
f=request.files['file']
print(request.files)
#secure_filename获取中文文件名需自行百度解决，不难
f.save(os.path.join(app.config['UPLOAD_FOLDER'],secure_filename(f.filename)))
return 'file uploaded successfully'
else:
return render_template('upload.html')
if __name__ == '__main__':
app.run(debug=True)
upload.html
<html>
<head>
<title>File Upload</title>
</head>
<body>
<form action="http://localhost:5000/uploader" method="POST" enctype="multipart/form-data">
<input type="file" name="file" />
<input type="submit" value="提交" />
</form>
</body>
</html>
http://localhost:5000/upload
I chose a picture and submitted it
to note that when using secure_filenameto get the Chinese file name, the Chinese will be omitted. There are many blogs on the Internet that have written solutions, so I won’t make any changes
It shows that the submission is successful
and the uploaded file is saved in uploadthe folder
Flask extensions/find extensions
The extension of Flask is usually named Flask-Fooor find the address of the Flask extensionFoo-Flask
by pipinstalling it . This blog is here first . The next blog will learn more about several extensions.