Introduction

When you want to handle basically fixed constant values such as domain name and site name in Django template, use the function called Context Processor and do not pass the constant from the view side each time, like a constant from within the template Can be handled.

environment

Django 2.2

What is Context Processor?

Context Processor is a function that can describe the process of adding variables when passing a context object from a view to a template. Csrf_token etc. used in the template are implemented by this mechanism.

Creating a Context Processor

The Context Processor is defined as a function that takes a HTTP Request object as an argument and returns a dictionary-type object.

Create the function name with any name, and create the file under the application directory.

`hogeapp/context_processors.py`


def my_context_processor(req):
    return {
        'domain_name': 'https://hogehoge.com',
        'site_name': 'Hogehoge Site',
    }

In the above example, the dictionary object is simply returned, but you can also describe the process in the same way as a normal function. You can also use this to refer to a constant defined separately in an external file, or change the value of an environment variable depending on the environment.

config.py settings

To use the created Context Processor, you need to set it in config.py. Add the function created in the previous section to context_processors in OPTIONS of TEMPLATES defined in config.py.

`config.py`


TEMPLATES = [
    {
        'OPTIONS': {
            'context_processors': [
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
                'hogeapp.context_processors.my_context_processor', #add to
            ],
        },
    },
]

How to call from a template

Variables added by the Context Processor can be used from within the template in the same way as variables in a normal context.

`template.html`


<link rel="icon" href="{{ domain_name }}/favicon.ico">
<title>{{ site_name }}</title>

reference

The Django template language: for Python programmers |Django documentation| Django https://docs.djangoproject.com/ja/2.2/ref/templates/api/#writing-your-own-context-processors

[PYTHON] Handle constants in Django templates