Custom Context Processors in Django.

What's the need of context processors? 😇

Sometimes you want to make a variable accessible to all templates in a project.

Two ways to access a variable in all templates:

1. Hard Way: By providing the same variable in the context of each view. 😐

2. Easy Way: creating a custom context processor 😋

Personally I don't like the hard way, cause then I have to write the same code in each view.

Let's see how it can be done the easy way.

Consider a situation where you need to display a banner image in each page of your website, the banner image will be fetched from the database.

Model for the banner image:

#models.py
class BannerImage(models.Model):
    image = models.ImageField(upload_to='img')

We can access the banner image in each page using the context processor.

Write Custom Context Processor 🙌

Create a new file context_processors.py inside your app and write a function which will return a dictionary containing the variable we want to use.

#context_processors.py

from .models import BannerImage

def access_banner_image(request):
    """
      The context processor must return a dictionary.
    """
    bannerImage = BannerImage.objects.latest('-id') #query the latest banner image
    return {'bannerImage':bannerImage} 

access_banner_image is the custom context processors we just created, add it to the context_processors option in the TEMPLATES setting so that the variable bannerImage is accessible in all templates.

#settings.py
TEMPLATES = [
    {
        #under OPTIONS key
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
               #context processor written by us.
           'appname.context_processors.access_banner_image'
],
        },
    },
]

We are done 🎉 , the bannerImage variable will be now accessible in all the templates.

Example:

<img src="{{bannerImage.image.url}}" alt=''/>

Thanks For Reading my post.🙂

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