from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.contrib.contenttypes.models import ContentType
from django.db.models.signals import post_save, post_delete
 
from lxml.etree import ElementTree, Element, SubElement
import StringIO
 
class XMLModelWriter:
    def __init__(self, model, file_name):
        self.model = model
        self.file_name = file_name
    def write(self):
        content_type = ContentType.objects.get_for_model(model=self.model)
        try:
            model_class = content_type.model_class()
            object_name = model_class._meta.object_name
            root = Element((object_name + 's').lower())
            element_tree = ElementTree(root)
            for object in model_class.objects.all():
                element = SubElement(root, object_name.lower())
                for field in object._meta.fields:
                    child = SubElement(element, field.name)
                    value = getattr(object, field.name)
                    if value != None:
                        if isinstance(value, models.base.Model):
                            # This field is a foreign key, so save the primary key
                            # of the referring object
                            pk_name = value._meta.pk.name
                            pk_value = getattr(value, pk_name)
                            child.text = unicode(pk_value)
                        else:
                            print value
                            child.text = unicode(value)
            new_file = open(self.file_name, 'w')
            element_tree.write(new_file, pretty_print=True, xml_declaration=True, encoding='utf-8')
        except ContentType.DoesNotExist:
            pass
 
class Item(models.Model):
    picture = models.CharField("Picture", blank=True, max_length=100)
    title = models.CharField("Title", blank=True, max_length=100)
    link = models.URLField("Link", verify_exists=False, blank=True)
    color = models.CharField("Color", blank=True, max_length=100)    
 
    def __unicode__(self):
        return self.title
 
    class Meta:
        verbose_name = "Item"
        verbose_name_plural = "Items"
def item_handler(sender, **kwargs):
    writer = XMLModelWriter(Item, 'D:/test/items.xml')
    writer.write() 
 
post_save.connect(item_handler, sender=Item)
post_delete.connect(item_handler, sender=Item)