Plone: running Plone without copies of blobs

// under blob blobs files patch plone problem python

Having a bad day? Just bombed your only copies of some files that you’d been storing as blobs together with your Plone database? Maybe you had the blobs stored incorrectly on your Zeo client, rather than the server, and then in a hasty effort to free some space (due to an on-going issue with blobs eating HDD space), deleted them. Whoops..they’re gone and their references are still in your Plone database. Or, in a less disastrous situation, maybe you just want to be able to run your Plone database without needing lost blobs? Read on.The suggestion, as mentioned elsewhere on the Interwebs, is to catch the exception that gets raised on accessing relevant blobs. The two locations to catch (as of plone.app.blob 1.0b18) are:

plone/app/blob/mixins.py

def getScale(self, instance, scale=None, **kwargs):
    """ get scale by name or original """
    try:
        if scale is None:
            return self.getUnwrapped(instance, **kwargs)
        handler = IImageScaleHandler(self, None)
        if handler is not None:
            return handler.getScale(instance, scale)
    except:
        pass
    return None

plone/app/blob/field.py

def get_size(self):
    """ return the size of the blob """
    try:
        blob = openBlob(self.blob)
        size = fstat(blob.fileno()).st_size
        blob.close()
    except:
        size = 100
    return size

If you put these try/catch statements in, you’ll stop your site from dying when accessing the View and Edit pages for your content. This means you can safely replace lost blobs with files again, or otherwise just use your site without the files, like if your client sends you only the database to save on size. Happy days.

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