Hi team,

Currently, validating the size of an uploaded file (e.g., setting a max/min size for a profile picture) requires writing custom validator logic. This is a very common task in many projects that handle file uploads.

I think it would be really helpful for the framework to provide built-in validators for this. I'm proposing the addition of MaxFileSizeValidator and MinFileSizeValidator.

They could be used directly in a serializer like this:

from rest_framework import serializers
from rest_framework.validators import MaxFileSizeValidator, MinFileSizeValidator

class FileUploadSerializer(serializers.Serializer):
    file = serializers.FileField(validators=[
        MaxFileSizeValidator(1024 * 1024),  # 1MB max
        MinFileSizeValidator(1024),        # 1KB min
    ])

This would save developers from writing boilerplate code and provide a standard, reliable way to handle a common validation scenario for both FileField and ImageField.

I've already opened a pull request with a full implementation, including tests and documentation:

Related PR: #9738

Would love to hear your thoughts. Thanks!