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Validating image dimensions in Django REST Framework

Ján Vorčák

@jvorcak

django drf rest test image processing

When uploading an image through Django REST Framework, sometimes you want to validate data such as image dimensions or file size on a serializer level.

You can do it using a following snippet.

from rest_framework.exceptions import ValidationError
from django.core.files.images import get_image_dimensions

MEGABYTE_LIMIT = 1
REQUIRED_WIDTH = 200
REQUIRED_HEIGHT = 200

def logo_validator(image):
    filesize = image.size
    width, height = get_image_dimensions(image)

    if width != REQUIRED_WIDTH or height != REQUIRED_HEIGHT:
        raise ValidationError(f"You need to upload an image with {REQUIRED_WIDTH}x{REQUIRED_HEIGHT} dimensions")

    if filesize > MEGABYTE_LIMIT * 1024 * 1024:
        raise ValidationError(f"Max file size is {MEGABYTE_LIMIT}MB")

class OrganisationDetailSerializer(serializers.ModelSerializer):
    class Meta:
        model = Organisation
        fields = ('id', 'name', 'slug', 'logo',)

    slug = serializers.ReadOnlyField()
    logo = ImageField(validators=[logo_validator])