Change the stream position after reading in validators #218
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It ensures that the image's stream position is always at the start after running validators to prevent issues with further file reading - e.g. another validator which doesn't seek, or another form validation since
seek(0)
is called at the end.This fixes an issue that I encounter using Wagtail and StdImageField with size validators. I always have the error Upload a valid image. The file you uploaded was either not an image or a corrupted image. for the image field. I presume
to_python()
is called on the field after the form validation. I didn't add a relevant test since it could require too much steps to encounter this issue.