edan_f0/oscar/apps/product/abstract_models.py

"""
Models of products
"""
import re
from itertools import chain

from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.template.defaultfilters import slugify
from django.core.urlresolvers import reverse
from django.core.exceptions import ObjectDoesNotExist

from oscar.apps.product.managers import BrowsableItemManager

def _convert_to_underscores(str):
    u"""
    For converting a string in CamelCase or normal text with spaces
    to the normal underscored variety
    """
    without_whitespace = re.sub('\s+', '_', str.strip())
    s1 = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', without_whitespace)
    return re.sub('([a-z0-9])([A-Z])', r'\1_\2', s1).lower()


class AbstractItemClass(models.Model):
    u"""Defines an item type (equivqlent to Taoshop's MediaType)."""
    name = models.CharField(_('name'), max_length=128)
    slug = models.SlugField(max_length=128, unique=True)
    options = models.ManyToManyField('product.Option', blank=True)

    class Meta:
        abstract = True
        ordering = ['name']
        verbose_name_plural = "Item classes"

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug= slugify(self.name)
        super(AbstractItemClass, self).save(*args, **kwargs)

    def get_absolute_url(self):
        return reverse('oscar-product-item-class', kwargs={'item_class_slug': self.slug})

    def __unicode__(self):
        return self.name


class AbstractItem(models.Model):
    u"""The base product object"""
    # If an item has no parent, then it is the "canonical" or abstract version of a product
    # which essentially represents a set of products.  If a product has a parent
    # then it is a specific version of a product.
    # 
    # For example, a canonical product would have a title like "Green fleece" while its 
    # children would be "Green fleece - size L".
    
    # Universal product code
    upc = models.CharField(_("UPC"), max_length=64, blank=True, null=True, db_index=True,
        help_text="""Universal Product Code (UPC) is an identifier for a product which is 
                     not specific to a particular supplier.  Eg an ISBN for a book.""")
    
    # No canonical product should have a stock record as they cannot be bought.
    parent = models.ForeignKey('self', null=True, blank=True, related_name='variants',
        help_text="""Only choose a parent product if this is a 'variant' of a canonical product.  For example 
                     if this is a size 4 of a particular t-shirt.  Leave blank if this is a CANONICAL PRODUCT (ie 
                     there is only one version of this product).""")
    
    # Title is mandatory for canonical products but optional for child products
    title = models.CharField(_('Title'), max_length=255, blank=True, null=True)
    slug = models.SlugField(max_length=255, unique=False)
    description = models.TextField(_('Description'), blank=True, null=True)
    item_class = models.ForeignKey('product.ItemClass', verbose_name=_('item class'), null=True,
        help_text="""Choose what type of product this is""")
    attribute_types = models.ManyToManyField('product.AttributeType', through='ItemAttributeValue',
        help_text="""An attribute type is something that this product MUST have, such as a size""")
    item_options = models.ManyToManyField('product.Option', blank=True, 
        help_text="""Options are values that can be associated with a item when it is added to 
                     a customer's basket.  This could be something like a personalised message to be
                     printed on a T-shirt.<br/>""")
    
    related_items = models.ManyToManyField('product.Item', related_name='relations', blank=True, help_text="""Related 
        items are things like different formats of the same book.  Grouping them together allows
        better linking betwen products on the site.<br/>""")
    
    # Recommended products
    recommended_items = models.ManyToManyField('product.Item', through='ProductRecommendation', blank=True)
    
    date_created = models.DateTimeField(auto_now_add=True)

    # This field is used by Haystack to reindex search
    date_updated = models.DateTimeField(auto_now=True, db_index=True)

    objects = models.Manager()
    browsable = BrowsableItemManager()

    # Properties

    @property
    def options(self):
        return list(chain(self.item_options.all(), self.get_item_class().options.all()))

    @property
    def is_top_level(self):
        u"""Return True if this is a parent product"""
        return self.parent_id == None
    
    @property
    def is_group(self):
        u"""Return True if this is a top level product and has more than 0 variants"""
        return self.is_top_level and self.variants.count() > 0
    
    @property
    def is_variant(self):
        u"""Return True if a product is not a top level product"""
        return not self.is_top_level

    @property
    def min_variant_price_incl_tax(self):
        u"""Return minimum variant price including tax"""
        return self._min_variant_price('price_incl_tax')
    
    @property
    def min_variant_price_excl_tax(self):
        u"""Return minimum variant price excluding tax"""
        return self._min_variant_price('price_excl_tax')

    @property
    def has_stockrecord(self):
        u"""Return True if a product has a stock record, False if not"""
        try:
            sr = self.stockrecord
            return True
        except ObjectDoesNotExist:
            return False

    @property
    def score(self):
        try:
            pr = self.productrecord
            return pr.score
        except ObjectDoesNotExist:
            return 0

    def attribute_summary(self):
        u"""Return a string of all of a product's attributes"""
        return ", ".join([attribute.__unicode__() for attribute in self.attributes.all()])

    def get_title(self):
        u"""Return a product's title or it's parent's title if it has no title"""
        title = self.__dict__.setdefault('title', '')
        if not title and self.parent_id:
            title = self.parent.title
        return title
    
    def get_item_class(self):
        u"""Return a product's item class"""
        if self.item_class:
            return self.item_class
        if self.parent.item_class:
            return self.parent.item_class
        return None

    # Helpers
    
    def _min_variant_price(self, property):
        u"""Return minimum variant price"""
        prices = []
        for variant in self.variants.all():
            if variant.has_stockrecord:
                prices.append(getattr(variant.stockrecord, property))
        if not prices:
            return None
        prices.sort()
        return prices[0]

    class Meta:
        abstract = True
        ordering = ['-date_created']

    def __unicode__(self):
        if self.is_variant:
            return "%s (%s)" % (self.get_title(), self.attribute_summary())
        return self.get_title()
    
    @models.permalink
    def get_absolute_url(self):
        u"""Return a product's absolute url"""
        return ('oscar-product-item', (), {
            'item_class_slug': self.get_item_class().slug, 
            'item_slug': self.slug,
            'item_id': self.id})
    
    def save(self, *args, **kwargs):
        if self.is_top_level and not self.title:
            from django.core.exceptions import ValidationError
            raise ValidationError("Canonical products must have a title")
        if not self.slug:
            self.slug = slugify(self.get_title())
        super(AbstractItem, self).save(*args, **kwargs)


class ProductRecommendation(models.Model):
    u"""
    'Through' model for product recommendations
    """
    primary = models.ForeignKey('product.Item', related_name='primary_recommendations')
    recommendation = models.ForeignKey('product.Item')
    ranking = models.PositiveSmallIntegerField(default=0)


class AbstractAttributeType(models.Model):
    u"""Defines an attribute. (Eg. size)"""
    name = models.CharField(_('name'), max_length=128)
    code = models.SlugField(_('code'), max_length=128)
    has_choices = models.BooleanField(default=False)

    class Meta:
        abstract = True
        ordering = ['code']

    def __unicode__(self):
        return self.name

    def save(self, *args, **kwargs):
        if not self.code:
            self.code = _convert_to_underscores(self.name)
        super(AbstractAttributeType, self).save(*args, **kwargs)
        

class AbstractAttributeValueOption(models.Model):
    u"""Defines an attribute value choice (Eg: S,M,L,XL for a size attribute type)"""
    type = models.ForeignKey('product.AttributeType', related_name='options')
    value = models.CharField(max_length=255)

    class Meta:
        abstract = True

    def __unicode__(self):
        return u"%s = %s" % (self.type, self.value)


class AbstractItemAttributeValue(models.Model):
    u"""
    The "through" model for the m2m relationship between product.Item
    and product.AttributeType.  This specifies the value of the attribute
    for a particular product.
    
    Eg: size = L
    """
    product = models.ForeignKey('product.Item', related_name='attributes')
    type = models.ForeignKey('product.AttributeType')
    value = models.CharField(max_length=255)
    
    class Meta:
        abstract = True
        
    def __unicode__(self):
        return u"%s: %s" % (self.type.name, self.value)
    
    
class AbstractOption(models.Model):
    u"""
    An option that can be selected for a particular item when the product
    is added to the basket.  
    
    Eg a list ID for an SMS message send, or a personalised message to 
    print on a T-shirt.  
    
    This is not the same as an attribute as options do not have a fixed value for 
    a particular item - options, they need to be specified by the customer.
    """
    name = models.CharField(_('name'), max_length=128)
    code = models.SlugField(_('code'), max_length=128)
    
    REQUIRED, OPTIONAL = ('Required', 'Optional')
    TYPE_CHOICES = (
        (REQUIRED, _("Required - a value for this option must be specified")),
        (OPTIONAL, _("Optional - a value for this option can be omitted")),
    )
    type = models.CharField(_("Status"), max_length=128, default=REQUIRED, choices=TYPE_CHOICES)
    
    class Meta:
        abstract = True
        
    def __unicode__(self):
        return self.name
    
    def save(self, *args, **kwargs):
        if not self.code:
            self.code = _convert_to_underscores(self.name)
        super(AbstractOption, self).save(*args, **kwargs)