Question: Control which forms/fields use the S3FileInputMixin

[mfisco]

Hello,

I’ve been trying to integrate django-s3file into a Django project that involves dynamically generated forms within formsets. Specifically, I use custom JavaScript to add extra forms to a formset dynamically. However, these dynamically added forms do not have valid signed POST URLs for S3 file uploads, which causes some issues.

Currently, it seems that the S3FileInputMixin is automatically applied to all forms by default. Is there a way to apply the mixin to only certain forms/fields selectively?

Thank you!

[codingjoe]

Hi @mfisco,

Thank you for reaching out. Yes, that is possible. You simply need to remove s3file for your INSTALLED_APPS list.

Cheers!
Joe

[mfisco]

Hi @codingjoe,

Thanks for the reply!

I should have been clearer in my original question, but I wanted to see if it had built-in support for this. For example, take the following:

# settings.py
STORAGES = {
    "default": {
        "BACKEND": "s3file.storages_optimized.S3OptimizedUploadStorage",
    },
    ...
}
S3FILE_UPLOAD_PATH = "tmp/s3file"



# app/forms.py
class CustomS3FileInput(S3FileInputMixin, forms.ClearableFileInput):
    pass


class LargeFilesForm(forms.Form):
    file = forms.FileField(widget=CustomS3FileInput())

Besides having to manually copy the s3file.js script to our static files directory (since s3file isn't included in the INSTALLED_APPS list), LargeFilesForm works great when using the S3OptimizedUploadStorage backend.

However, when using the S3OptimizedUploadStorage on forms that don't have a S3FileInputMixin widget, the form will raise an error. For example:

class SmallFilesForm(forms.Form):
    file = forms.FileField(widget=forms.ClearableFileInput())

# Raises the following error:
# TypeError: The content object must be a S3 object and contain a valid key.

Are you aware of a way to make the S3OptimizedUploadStorage work for both forms that have a S3FileInputMixin widget and those that don't?

[codingjoe]

Ah, I see. OK. You can set a storage per model field in Django. This would allow you to mix and match. However, are you dealing with really large files at the moment? If not, I wouldn't necessarily recommend using the optimized storage. Usually, you can ignore the overhead of IO inside an AWS region. Of course, that hit's it's limits if you are dealing with video files. But for everything else, you shouldn't notice any difference. If you have further questions, please ask. Cheers! Joe

[mfisco]

The files can get relatively large (between 200 and 500MB); however, you were right -- the IO overhead is pretty minimal. Thanks again for your help, Joe!