coercing to Unicode Django -

i'm building sample django application collects few input products , picture..

i have integrated product model forms , trying add new products through django admin...

i following error, when try create new product..

error:

typeerror @ /admin/catalog/product/add/ coercing unicode: need string or buffer, tuple found   request method: post   request url: http://127.0.0.1:8000/admin/catalog/product/add/   django version: 1.4.3   exception type: typeerror   exception value: coercing unicode: need string or buffer, tuple found   exception location: c:\python27\lib\ntpath.py in abspath, line 471  

code:

models.py

class product(models.model):     name = models.charfield(max_length=255,unique=true)     slug = models.slugfield(max_length=255,unique=true,help_text="unique value product page url, created name.")     brand = models.charfield(max_length=50)     sku = models.charfield(max_length=50)     price = models.decimalfield(max_digits=9,decimal_places=2)     old_price = models.decimalfield(max_digits=9,decimal_places=2,blank=true,default=0.00)     #image = models.charfield(max_length=50)     is_active = models.booleanfield(default=true)     is_bestseller = models.booleanfield(default=false)     is_featured = models.booleanfield(default=false)     quantity = models.integerfield()     description = models.textfield()     meta_keywords = models.charfield(max_length=255,help_text="comma-delimited set of seo keywords meta tag")     meta_description = models.charfield(max_length=255,help_text="content description meta tag")     created_at = models.datetimefield(auto_now_add=true)     updated_at = models.datetimefield(auto_now=true)     categories = models.manytomanyfield(category)     image = models.imagefield(upload_to='images/products/main')     thumbnail = models.imagefield(upload_to='images/products/thumbnails')     image_caption = models.charfield(max_length=200)      class meta:         db_table = 'products'         ordering = ['-created_at']      def __unicode__(self):         return self.name      @models.permalink     def get_absolute_url(self):         return ('catalog_product',(),{'product_slug':self.slug})     @property         def sale_price(self):         if self.old_price > self.price:             return self.price         else:             return none 

settings.py

media_root = "static/", 

request object:

get  no data  post   variable  value   sku u'239'  meta_description u'iphone'  meta_keywords u'iphone'  name u'apple iphone'  _save u'save'  is_active u'on'  price u'239'  description u'iphone'  old_price u'200'  slug u'apple_iphone'  image_caption u'phone'  csrfmiddlewaretoken u'suo3uq5sfz0bo153cxicixpcmnv5hhsn'  brand u'apple'  categories u'1'  quantity u'1'   files   variable  value   image <inmemoryuploadedfile: snip.png (image/png)>  thumbnail <inmemoryuploadedfile: snip.png (image/png)> 

is there problem uploading png file in image object?