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Flask how to use render_template, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

Our previous view functions return simple strings like 'Hello Wolrd''. How can we return a html? First of all, let's create a html file in the templates folder, and write something like this:

IndexThis is index page

We can use the send_static_file method of the Flask object app to make the view function return a static html file, but now instead of using this method, we use the render_template function of flask, which is more powerful.

Import render_template from flask. The overall code is as follows:

From flask import Flask, render_templateimport configapp = Flask (_ _ name__) app.config.from_object (config) @ app.route ('/') def index (): return render_template ('index.html') if _ _ name__ = =' _ main__': app.run ()

The render_template function automatically finds the corresponding html in the templates folder, so we don't have to write the complete html file path. Visit the address'/ 'with a browser, and the result is as follows:

So why is it called a template? Because render_template can not only render static html files, but also pass parameters to html, so that a html template displays different content according to different parameters, this is because flask uses jinja2 as a template engine. To use a template, pass variables as key=value in the render_template parameter, and use {{key}} in html to display the passed variables, for example:

# View function @ app.route ('/') def index (): return render_template ('index.html', contents='This is index page') # html Index {{contents}}

The result displayed by the browser is the same as above. We can also pass an instance of a class directly and access the properties of the class in the template. For example, suppose a class object obj has an and b attributes. The code for the key part is as follows:

# return render_template ('index.html', object=obj)... # html in the view function

A: {{object.a}}

B: {{object.b}}

Passing in a dictionary is also possible, and you can use either dict [key] or dict.key in the template.

Using the filter, you can process the passed variables in html in the format {{variable | filter}}. For example, if you modify the previous {{contents}} to {{contents | upper}}, the content displayed by the browser will become:

So we can easily understand that a filter is actually a function that takes a variable as a parameter and returns the processed result. At the back end, you can also use the upper () function of the string object to deal with it and then pass it to the template. The effect is exactly the same. Jinja2 comes with some filters, such as length/reverse/lower, etc., and we can customize the filter according to our needs. The template also supports operations such as {{variable | filter 1 | filter 2 |.}}. If you want to learn more, you can search the jinja2 filter to learn more.

If else and for in control statements can also be used in the template. Unlike variables using {{}}, control statements should be placed in {%}, for example, a list is passed in the previous contents:

Contents= [i for i in range (10)]

The code in html is as follows:

{% for i in contents%} {{I}} {# Note I also use two braces #} {% endfor%}

Use for to iterate through the contents of contents and display them with {{I}}, with a comment with {# #}, and note that you need to use {% endfor%} to indicate the end of the loop, because html does not determine the area of the loop by indentation like python, and so does if. The browser displays the results:

Finally, for is used in conjunction with if:

Header {% for i in contents%}

{% if I% 2 = = 0%} {{I}} is even {# Note I also use two braces #} {% else%} {{I}} is odd {% endif%}

{% endfor%} is it helpful for you to read the above content? If you want to know more about the relevant knowledge or read more related articles, please follow the industry information channel, thank you for your support.

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