Django Rest frameworks: request.Post vs request.data?

The docs cover this:

request.data returns the parsed content of the request body. This is similar to the standard request.POST and request.FILES attributes except that:

• It includes all parsed content, including file and non-file inputs.
• It supports parsing the content of HTTP methods other than POST, meaning that you can access the content of PUT and PATCH requests.
• It supports REST framework's flexible request parsing, rather than just supporting form data. For example you can handle incoming JSON data in the same way that you handle incoming form data.

The last two are the important ones. By using request.data throughout instead of request.POST, you're supporting both JSON and Form-encoded inputs (or whatever set of parsers you have configured), and you'll be accepting request content on PUT and PATCH requests, as well as for POST.

Is one more flexible?

Yes. request.data is more flexible.

I think some users get redirected here when trying to get data from the POST body in vanilla Django (when they aren't using the Django REST framework). In case you're using a basic Django endpoint you use request.body to get data from the body of the request so long as it isn't form data that's being sent to the server (in that case use request.POST). This is different from the request.data attribute that is needed for accessing data with Django REST framework.

from json import loads
def login(request):
    json = loads(request.body)
    print(json['username']) # Prints the value associated with 

loads(request.body) is needed because request.body returns a byte string. loads will convert that byte string into a dictionary.

request.BODY, request.data, and request.DATA are all undefined for Django's default request object.

https://docs.djangoproject.com/en/3.1/ref/request-response/

Notice there is no .data attribute under HttpRequest which differs from the Django REST framework request.

(This doesn't answer the original question but might help users that end up here who aren't using the REST framework)