Month: October 2015

If you have any ImageField or FileField in your model, you can easily display the full URL (including the hostname/domain) for the file/image. Django REST Framework’s model serializers would do it for you. However, to get the hostname/domain name, the serializer needs a “request context” so it can infer the necessary parts and build a full url.

So if you’re manually invoking a serializer, please pass a request context like this:

If you use ModelViewSet, DRF will automatically pass the request context while initializing the serializer. So in that case you don’t need to do anything. You need to pass the context only when you’re manually creating a serializer instance.

Here’s the use case, I need to add some extra fields to my serializer depending on a request. For example, if the query string contains “extra=true”, then add the extra fields. Luckily, serializers get a “context” argument when they are initialized. We can use this to customize our serializers as needed.

The fields defined on a serializer are available in a instance variable named “fields”. So we can add/delete/edit fields from it. Let’s see an example:

Please note, here we have used another serializer (UserLocationSerializer) from inside our main serializer. The second one is being initialized by us. So it would not get the context. If we need to do something down there as well, then we need to pass it ourselves.

Now the second serializer will get the request too and we can use the same way to customize it!