能否改写django-file-resubmit模块以适配DBAdminClearableFileInput父类？

Absolutely! There are several clean, flexible approaches to adapt django-file-resubmit to use DBAdminClearableFileInput as the parent class without modifying the module's source code directly. Here are the most practical solutions:

1. Add a Configurable Parent Class via Django Settings (Best Practice) #

If you're willing to fork django-file-resubmit or contribute a PR (this is the most maintainable long-term fix), modify the module's widgets.py to pull the parent class from Django settings:

# django-file-resubmit/widgets.py
from django.conf import settings
from django.forms import ClearableFileInput

# Default to Django's built-in class, but allow overriding via settings
DEFAULT_PARENT_CLASS = ClearableFileInput
PARENT_FILE_INPUT_CLASS = getattr(settings, 'FILE_RESUBMIT_PARENT_INPUT', DEFAULT_PARENT_CLASS)

# Handle string paths (e.g., 'dbadmin.widgets.DBAdminClearableFileInput')
if isinstance(PARENT_FILE_INPUT_CLASS, str):
    from django.utils.module_loading import import_string
    PARENT_FILE_INPUT_CLASS = import_string(PARENT_FILE_INPUT_CLASS)

class ResubmitFileInput(PARENT_FILE_INPUT_CLASS):
    # Keep all existing logic for the class intact
    ...

Then in your project's settings.py, define the override:

FILE_RESUBMIT_PARENT_INPUT = 'dbadmin.widgets.DBAdminClearableFileInput'

This keeps the module flexible for all users, not just your use case.

2. Monkey-Patch the Class at Runtime #

If you can't modify the django-file-resubmit source code, you can dynamically alter the parent class of ResubmitFileInput when your Django app starts. Add this to your app's apps.py:

# your_app/apps.py
from django.apps import AppConfig
from django_file_resubmit.widgets import ResubmitFileInput
from dbadmin.widgets import DBAdminClearableFileInput

class YourAppConfig(AppConfig):
    name = 'your_app'

    def ready(self):
        # Replace the parent class with DBAdminClearableFileInput
        # Preserve any other parent classes if needed (adjust the tuple as required)
        ResubmitFileInput.__bases__ = (DBAdminClearableFileInput,)

Make sure your app is listed after both django_file_resubmit and your DBAdmin module in INSTALLED_APPS to ensure the classes are loaded before patching.

3. Create a Wrapper Widget Class #

Another low-impact option is to create your own widget that inherits from both DBAdminClearableFileInput and ResubmitFileInput, combining their functionality:

# your_app/widgets.py
from django_file_resubmit.widgets import ResubmitFileInput
from dbadmin.widgets import DBAdminClearableFileInput

class DBAdminResubmitFileInput(DBAdminClearableFileInput, ResubmitFileInput):
    # Resolve any method conflicts here (e.g., if both classes define `render` or `value_from_datadict`)
    # Example: Prioritize ResubmitFileInput's logic for file resubmission
    def value_from_datadict(self, data, files, name):
        return ResubmitFileInput.value_from_datadict(self, data, files, name)

Then use this new class in your forms instead of the original ResubmitFileInput.

Each approach has its tradeoffs: the first is the most scalable, the second avoids modifying external code, and the third gives you full control over the combined behavior.

内容的提问来源于stack exchange，提问作者mirek