Article Directory
0. Preface
FlaskIt is the use of a Pythonlightweight written Webapplication framework.
1. Installation
pip install flask -i https://pypi.douban.com/simple
1.1 The simplest case
from flask import Flask
app = Flask(__name__) # __main__
@app.route('/') # rule 参数表示与该函数的URL绑定。
def hello_world():
return 'Hello World'
if __name__ == '__main__':
app.run() # app.run(host, port, debug, options)
2. Simple to use
2.1 Routing
@app.route('/hello/<name>') # http:// localhost:5000/hello/w3cschool
def hello_name(name):
return 'Hello %s!' % name
@app.route('/blog/<int:postID>') # http://localhost:5000/blog/11
def show_blog(postID):
return 'Blog Number %d' % postID
@app.route('/rev/<float:revNo>') # http://localhost:5000/rev/1.1
def revision(revNo):
return 'Revision Number %f' % revNo
2.2 url_for()Function
Dynamically build specific functions URL, such as:
@app.route('/admin')
def hello_admin():
return 'Hello Admin'
@app.route('/guest/<guest>')
def hello_guest(guest):
return 'Hello %s as Guest' % guest
@app.route('/user/<name>')
def hello_user(name):
if name =='admin':
return redirect(url_for('hello_admin'))
else:
return redirect(url_for('hello_guest',guest = name))
2.3 method specification
<form action = "http://localhost:5000/login" method = "post">
<p>Enter Name:</p>
<p><input type = "text" name = "nm" /></p>
<p><input type = "submit" value = "submit" /></p>
</form>
@app.route('/login',methods = ['POST', 'GET'])
def login():
if request.method == 'POST':
user = request.form['nm']
return redirect(url_for('success',name = user))
else:
user = request.args.get('nm')
return redirect(url_for('success',name = user))
POSTThrough request.form['nm']acquisition, GETthrough request.args.get('nm')acquisition.
2.4 Using templates
Create a new templatesfolder, and then create a new hello.htmltemplate file below .
Then, template_folder="templates"specify the template folder in use, and then use the template file as follows:
from flask import Flask, render_template
app = Flask(__name__, template_folder="templates") # __main__
@app.route('/')
def hello_world():
return render_template("hello.html")
if __name__ == '__main__':
app.run() # app.run(host, port, debug, options)
2.5 template variables
In the template, springbootit is theamleafsimilar to the template in. You can use variables, pass in values, that is, template variables.
In htmluse {
{ my_str }}in use in render_templatethe Incoming my_str:
htmltemplate files:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
Hello {
{ username }}
</body>
</html>
Server program:
from flask import Flask, render_template
app = Flask(__name__, template_folder="templates") # __main__
@app.route('/<username>')
def hello_world(username):
return render_template("hello.html", username=username)
if __name__ == '__main__':
app.run() # app.run(host, port, debug, options)
2.6 Static files
2.6.1 Take cssfile as an example
Common css, js, imgsfiles and so is we need a static resource files. Similarly, you can use
app = Flask(__name__, template_folder="templates", static_folder="static")
To specify the path of the static resource.
Add a new staticfolder, then add a new cssfolder under it, and create a index.cssfile.
index.cssThe content of the file is as follows:
*,body{
background-color: #333;
}
.test{
color: red;
font-size: 30px;
}
In the corresponding htmltemplate file, use the following:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<link type="text/css" rel="styleSheet" href="{
{ url_for('static', filename = 'css/index.css') }}"/>
<title>Title</title>
</head>
<body>
<p class="test">Hello {
{ username }}</p>
</body>
</html>
Then the server program is as follows:
from flask import Flask, render_template
app = Flask(__name__, template_folder="templates", static_folder="static")
@app.route('/<username>')
def hello_world(username):
return render_template("hello.html", username=username)
if __name__ == '__main__':
app.run() # app.run(host, port, debug, options)
Effect:
Then, through a simple page analysis, index.cssthe access path that can be obtained is:
http://127.0.0.1:5000/static/css/index.css
2.6.2 Static image resources
Similarly, we can use image resources in the template, create a new static/img/tu.pngfile in the same way , and then we can reference it like this:
<img src="{
{ url_for('static',filename='img/tu.png')}}" />
2.6.3 Note
[Note] The above static resource files can be directly referenced by absolute paths, such as /static/css/index.css.
2.7 Request object
RequestThe important attributes of the object are listed below:
Form-It is a dictionary object that contains key and value pairs for form parameters and their values. Namely:POSTrequest.args-Parse the content of the query string, which isURLthe part after the question mark . Namely:GETrequest.CookiesCookie-A dictionary object that holds names and values.files-Data related to uploaded files.method-Current request method.