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[flask] static file and template rendering

2022-07-06 01:27:00 【Coriander Chrysanthemum】

Preface article ：
Flask Departure and implementation are based on Flask The smallest application

Static files Static Files

Static files are mainly web Some pictures will be used in the application ,css file ,js Files, etc. to achieve an elegant web page . This is also an indispensable part of dynamic websites . that Flask Will solve it for you .

use Flask document ： Just create a folder called static in your package or next to your module and it will be available at /static on the application. in other words , Create in the project path static Folder , Or create at the same level of the module /static Folder is ok ,flask You will find the contents of static files in these paths .
Static files also have a path in the system , Suppose there is a static/style.css The file of . Then you can use the following methods to locate ：

url_for('static', filename='style.css')

Template rendering Rendering Templates

If you use Python To build a through string splicing and so on HTML page , I'm afraid it will kill people . besides , You also have to consider injecting attacks, etc . With this demand , There is a concept of template engine , Popular said ： This gadget can put html Code and flask Apply the returned data for dynamic integration , And then render it as html The code is displayed on the browser . If you know Java in JSP、Thymeleaf I should have understood .Flask The default template rendering engine is Jinja2.

Render a template （ One html） It uses render_template() Method . What we need to do is to provide the name of the template and the variables to be passed to the template engine as keyword parameters . Here is a simple example of how to render a template ：

from flask import render_template

@app.route('/hello/')
@app.route('/hello/<name>')
def hello(name=None):
    return render_template('hello.html', name=name)

Flask Will be from templates Find the corresponding file in the folder , This templates Storage address and static similar . You can refer to the following understanding ：

modular

/application.py
/templates
    /hello.html

package

/application
    /__init__.py
    /templates
        /hello.html

Then for the template , We can use Jinja2 All functions of the template . This also has to know Jinja2 The document of ：Jinja2.
The following is a template use case ：

<!doctype html>
<title>Hello from Flask</title>
{
    % if name %}
  <h1>Hello {
    {
     name }}!</h1>
{
    % else %}
  <h1>Hello, World!</h1>
{
    % endif %}

In the template , We can also visit config、request、session and g These objects and url_for() and get_flashed_messages() function . What are these? I will continue to introduce them later , In short, it can be used directly in the template .

Some pages have public sections , As header 、 Navigation and footer , If you can put the public part into a template , Other templates can be simply reused . This is the inheritance of the template （inheritance）. This needs to be understood in depth , You can refer to the official .

Auto escape enabled , So if name contain HTML, It will escape automatically . If we can trust a variable and know that it is safe HTML（ for example , Because it comes from will wiki The tag is converted to HTML Module ）, We can use Markup Class or use | safe The filter marks it as a security template .

Markup A brief introduction to the use of class ：

from markupsafe import MarkUp
print(Markup('<strong>Hello %s!</strong>') % '<blink>hacker</blink>')
# Markup('<strong>Hello &lt;blink&gt;hacker&lt;/blink&gt;!</strong>')
print(Markup.escape('<blink>hacker</blink>'))
# Markup('&lt;blink&gt;hacker&lt;/blink&gt;')
print(Markup('<em>Marked up</em> &raquo; HTML').striptags())
# Marked up » HTML