Flask 简明教程

Flask – Redirect & Errors

Flask 类有一个 redirect() 函数。当被调用时，它返回一个响应对象，并且使用指定的HTTP状态码将用户重定向到另一个目标位置。

Flask class has a redirect() function. When called, it returns a response object and redirects the user to another target location with specified status code.

redirect() 函数的原型如下 −

Prototype of redirect() function is as below −

Flask.redirect(location, statuscode, response)

在上面的函数中 −

In the above function −

location parameter is the URL where response should be redirected.
statuscode sent to browser’s header, defaults to 302.
response parameter is used to instantiate response.

以下状态代码是标准化的 −

The following status codes are standardized −

HTTP_300_MULTIPLE_CHOICES
HTTP_301_MOVED_PERMANENTLY
HTTP_302_FOUND
HTTP_303_SEE_OTHER
HTTP_304_NOT_MODIFIED
HTTP_305_USE_PROXY
HTTP_306_RESERVED
HTTP_307_TEMPORARY_REDIRECT

default status 代码是 302 ，用于 ‘found’ 。

The default status code is 302, which is for ‘found’.

在以下示例中， redirect() 函数用于在登录尝试失败时再次显示登录页面。

In the following example, the redirect() function is used to display the login page again when a login attempt fails.

from flask import Flask, redirect, url_for, render_template, request
# Initialize the Flask application
app = Flask(__name__)

@app.route('/')
def index():
   return render_template('log_in.html')

@app.route('/login',methods = ['POST', 'GET'])
def login():
   if request.method == 'POST' and request.form['username'] == 'admin' :
      return redirect(url_for('success'))
   else:
      return redirect(url_for('index'))

@app.route('/success')
def success():
   return 'logged in successfully'

if __name__ == '__main__':
   app.run(debug = True)

Flask 类具有带错误代码的 abort() 函数。

Flask class has abort() function with an error code.

Flask.abort(code)

Code 参数采用以下值之一 −

The Code parameter takes one of following values −

400 − for Bad Request
401 − for Unauthenticated
403 − for Forbidden
404 − for Not Found
406 − for Not Acceptable
415 − for Unsupported Media Type
429 − Too Many Requests

让我们在上述代码中的 login() 函数中做一些小的更改。如果要显示 ‘Unauthourized’ 页面，请用调用 abort(401) 替换重新显示登录页面。

Let us make a slight change in the login() function in the above code. Instead of re-displaying the login page, if ‘Unauthourized’ page is to be displayed, replace it with call to abort(401).

from flask import Flask, redirect, url_for, render_template, request, abort
app = Flask(__name__)

@app.route('/')
def index():
   return render_template('log_in.html')

@app.route('/login',methods = ['POST', 'GET'])
def login():
   if request.method == 'POST':
      if request.form['username'] == 'admin' :
         return redirect(url_for('success'))
      else:
         abort(401)
   else:
      return redirect(url_for('index'))

@app.route('/success')
def success():
   return 'logged in successfully'

if __name__ == '__main__':
   app.run(debug = True)