Django Admin: Store and display Images in Postgres Binary field (By obligation)

Question

I have a small project of the backoffice for a pos program. actually the images are stored in binary field so, I must work with them. As example I have the following model for one categories table: models.py

class Categories(models.Model):
    id = models.CharField(primary_key=True, max_length=20, default=createid())
    name = models.CharField(unique=True, max_length=50)
    parentid = models.ForeignKey('self', db_column='parentid', blank=True, null=True)

    image = models.ImageField(upload_to="images", null=True)
    def __unicode__(self):              # __unicode__ on Python 2
        return '('+self.id+')'+self.name
    def save(self, *args, **kwargs):
        try:
            path1 = safe_join(os.path.abspath(settings.MEDIA_ROOT)+'\images', self.image)
            image_file = open(path1,'rb')
            file_content = image_file.read()

            self.image=file_content
        except:
            filename = 'no_image.png'
            path = safe_join(os.path.abspath(settings.MEDIA_ROOT), filename)
            #if not os.path.exists(path):
            #    raise ObjectDoesNotExist
            no_image = open(path, 'rb')
            file_content = no_image.read()
        super(Categories, self).save(*args, **kwargs)
    def image_thumb(self):
        if self.image:
            file_like=cStringIO.StringIO(self.image)

            return mark_safe(u'<img width="70" height="70" src="data:image/png;base64,%s" />') % file_like
        else:
            return '(No image)'
    image_thumb.short_description = 'Thumb'
    image_thumb.allow_tags = True

    class Meta:
        managed = False
        db_table = 'categories'

To avoid the database unnecessery structure changes, in models.py I changed the image column type to models.ImageField. In Database it is a binary field. Doing this and by overiding save method, i try to resolve the problem.

1)But when Itry to save the uploaded file I receive the following message:

DjangoUnicodeDecodeError at /admin/app/categories/34/ 'utf8' codec can't decode byte 0x89 in position 0: invalid start byte. You passed in '\x89PNG\r\n\x1a\n\x....<

2) I cannot retrieve the right format to display image in file_like varible

I use python 2.7 and django 1.7

Any help is highly happreciated

Jim Bob · Accepted Answer · 2016-04-23 13:17:36Z

5

To use the BinaryField, in the model do something like...

image_file = models.BinaryField(blank=True)

Then to read from a form POST...

image_file = request.FILES['image_file'].file.read()

Simple as that.

answered Apr 23, 2016 at 13:17

Jim Bob

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Bernhard Vallant · Accepted Answer · 2015-03-23 11:03:01Z

0

Try using Django's built-in BinaryField instead of the ImageField.

answered Mar 23, 2015 at 11:03

Bernhard Vallant

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1 Comment

user2012749 Over a year ago

Can you tell me how we can use BinaryField in my case?

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