Thumbnail tag failed error provides no details

[jplehmann]

Occasionally I get failures like this one but they provide no context as to which image failed making it difficult to debug when they are popping up occasionally on a busy web server. I don't know why this wouldn't have been included unless in this wrapper that details (such as the filename) was not available?

[ERROR] Thumbnail tag failed  [thumbnail:84] 
Traceback (most recent call last): 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/templatetags/thumbnail.py", line 59, in render 
    return self._render(context) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/templatetags/thumbnail.py", line 137, in _render 
    thumbnail = get_thumbnail(file_, geometry, **options) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/shortcuts.py", line 8, in get_thumbnail 
    return default.backend.get_thumbnail(file_, geometry_string, **options) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/base.py", line 125, in get_thumbnail 
    thumbnail) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/base.py", line 157, in _create_thumbnail 
    image = default.engine.create(source_image, geometry, options) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/engines/base.py", line 20, in create 
    image = self.orientation(image, geometry, options) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/engines/base.py", line 45, in orientation 
    return self._orientation(image) 
  File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/engines/pil_engine.py", line 71, in _orientation 
    exif = image._getexif() 
  File "/app/.heroku/python/lib/python2.7/site-packages/PIL/JpegImagePlugin.py", line 390, in _getexif 
    return _getexif(self) 
  File "/app/.heroku/python/lib/python2.7/site-packages/PIL/JpegImagePlugin.py", line 418, in _getexif 
    info = TiffImagePlugin.ImageFileDirectory(head) 
  File "/app/.heroku/python/lib/python2.7/site-packages/PIL/TiffImagePlugin.py", line 274, in __init__ 
    raise SyntaxError("not a TIFF IFD") 

[jplehmann]

For anyone finding this error message, I've also filed a bug with Pillow with this error in getting EXIF:

python-pillow/Pillow#2043

[jplehmann]

@mariocesar Can you recommend a solution here? Some users upload images to my site which are corrupted somehow, and subsequently I get this error logging popping up all of the time.

1. I want more information like the filename so I can diagnose the problem. As it is it's a mess to figure out what went wrong.
2. Second, I'd want to be able to detect the problem via an exception. For this I'm thinking I should exercise a lower level call which would actually give me a failure result value or exception.

[SalahAdDin]

@mariocesar Please.

[jsanchezs]

Yeah, please! =D

[jplehmann]

The problem was in fact a bug in the watermarking program these users were using resulting in corrupt EXIF, and I worked with the author to get that fixed.

The way I solved this issue was to always generate these thumbs in code (rather than template), and wrap in a try block. Additionally, I have a periodic process that tries to generate the thumbs rather than during the request cycle. If there's a problem with the image I log it with the necessary info, and remove the image so that the failure doesn't keep happening.

    def get_thumbnail(self, dims, upscale=False, **options):
        """ Use sorl to produce the thumbnail; this also caches it for later.
        """
        from sorl.thumbnail import get_thumbnail as sorl_get_thumbnail
        try:
            return sorl_get_thumbnail(self.best_image(), dims, upscale=upscale, **options)
        except SyntaxError:
            # Only catch SyntaxError: not a tiff, otherwise, I had Heroku rebooting
            # and caused me to remove a good image.
            log.error("Problem generating thumbnail for #%s @ %s. Removed it. %s",
                    self.id, dims, self.best_image().url, exc_info=True)
            # Remove all images.
            self.image = ""
            self.save()
            return None

[szuprefix]

File "/app/.heroku/python/lib/python2.7/site-packages/sorl/thumbnail/engines/pil_engine.py", line 71, in _orientation
exif = image._getexif()

`` python

def _orientation(self, image):
        try:
            exif = image._getexif()
        except (AttributeError, IOError, KeyError, IndexError):
            exif = None

        if exif:
            orientation = exif.get(0x0112)

            if orientation == 2:
                image = image.transpose(Image.FLIP_LEFT_RIGHT)
            elif orientation == 3:
                image = image.rotate(180)
            elif orientation == 4:
                image = image.transpose(Image.FLIP_TOP_BOTTOM)
            elif orientation == 5:
                image = image.rotate(-90).transpose(Image.FLIP_LEFT_RIGHT)
            elif orientation == 6:
                image = image.rotate(-90)
            elif orientation == 7:
                image = image.rotate(90).transpose(Image.FLIP_LEFT_RIGHT)
            elif orientation == 8:
                image = image.rotate(90)

        return image   

why except (AttributeError, IOError, KeyError, IndexError) ?
we got a SyntaxError("not a TIFF IFD") , not in the error list, this is the bug.
why not just except Exception ??
if could not get exif, just ignore, keep going.

[szuprefix]

all right , they have already removed the bug.

    def _orientation(self, image):
        try:
            exif = image._getexif()
        except:
            exif = None