Usage

Validate single file

The field can be used in forms or model forms like a normal FileField. If a user tries to upload a file which is too large or without a valid type, a form validation error will occur.

Note that the validation does not occur on the field itself (on save()), but when validated through a form.

Creating form from model

Create a model and add a field of type ConstrainedFileField. You can add a maximum size in bytes and a list of valid mime types that will be allowed. The list of all mime types is provided by the IANA. Setting none of the above, it behaves like a regular FileField:

from django.db import models
from constrainedfilefield.fields import ConstrainedFileField

class TestModel(models.Model):
    the_file = ConstrainedFileField(
                            null=True,
                            blank=True,
                            upload_to='testfile',
                            content_types=['image/png'],
                            max_upload_size=10240
                                    )

from django import forms
from myproject.models import TestModel

class TestModelForm(forms.ModelForm):
    class Meta:
        model = TestModel
        fields = ['the_file']

Building a form

from django import forms
from constrainedfilefield.fields import ConstrainedFileField

class TestNoModelForm(forms.Form):
    the_file = ConstrainedFileField(
                    null=True,
                    blank=True,
                    upload_to='testfile',
                    content_types=['image/png'],
                    max_upload_size=10240
                                    ).formfield()

Javascript file size validation

Additionally, to prevent user uploading too large files, a javascript checker can be set to the form field. In order to achieve that, you need to

1. Add constrainedfilefield to the INSTALLED_APPS. This will load the javascripts from the static files.

2. Activate this feature by setting js_checker=True when instantiating the ConstrainedFileField.

3. Include the javascript in the template where the form field is used:

   {% load static %}
   <script src="{% static 'constrainedfilefield/js/file_checker.js' %}"></script>
   

Validate single image

Same as above, using ConstrainedImageFileField instead.

The ConstrainedImageField offers additional constraints:

• min_upload_size to define minimal file size.
• [min|max]_upload_[width|height] to define min/max dimensions, respectively width and height.