Improved wishlist based on @dfalk's work

cartridge/shop/defaults.py

@@ -293,3 +293,15 @@
     editable=False,
     default=True,
 )
+
+register_setting(
+    name="SHOP_WISHLIST_NOTIFICATIONS",
+    label=_(
+        "Sends email notifications if an item in user's wishlist is in stock"
+    ),
+    description=_(
+        "Sends email notifications if an item in user's wishlist is in stock"
+    ),
+    editable=True,
+    default=True,
+)

cartridge/shop/managers.py

@@ -202,3 +202,36 @@ def get_valid(self, code, cart):
             if products.filter(variations__sku__in=cart.skus()).count() == 0:
                 raise self.model.DoesNotExist
         return discount
+
+
+class WishlistManager(Manager):
+
+    def from_request(self, request):
+        """
+        Gets current user's wishlist. Authenticated users' wishlists are stored
+        in the database, while unauthenticated users' are stored in a cookie.
+        Note that this method returns a `list` of SKUs in both cases, not a
+        `QuerySet` of `ProductVariation` objects.
+        """
+        if request.user.is_authenticated():
+            wishlist = []
+            skus = self.filter(user=request.user).values_list("sku", flat=True)
+            for sku in skus:
+                wishlist.append(sku)
+        else:
+            wishlist = request.COOKIES.get("wishlist", "").split(",")
+            if not wishlist[0]:
+                wishlist = []
+        return wishlist
+
+    def delete_for_request(self, sku_to_delete, request):
+        """
+        Delete item from user's wishlist. Authenticated users' wishlists are
+        stored in the database, while unauthenticated users' are stored in a
+        cookie. In the latter case, the SKU is removed directly from
+        `request.wishlist`, which is provided by `ShopMiddleware`.
+        """
+        if request.user.is_authenticated():
+            self.get(user=request.user, sku=sku_to_delete).delete()
+        else:
+            request.wishlist.remove(sku_to_delete)

cartridge/shop/middleware.py

@@ -1,7 +1,7 @@
 
 from mezzanine.conf import settings
 
-from cartridge.shop.models import Cart
+from cartridge.shop.models import Cart, Wishlist
 
 
 class SSLRedirect(object):
@@ -29,7 +29,4 @@ class ShopMiddleware(SSLRedirect):
     """
     def process_request(self, request):
         request.cart = Cart.objects.from_request(request)
-        wishlist = request.COOKIES.get("wishlist", "").split(",")
-        if not wishlist[0]:
-            wishlist = []
-        request.wishlist = wishlist
+        request.wishlist = Wishlist.objects.from_request(request)

cartridge/shop/models.py

@@ -1,9 +1,11 @@
 from decimal import Decimal
 from operator import iand, ior
 
+from django.contrib.auth.models import User
+from django.contrib.auth.signals import user_logged_in
 from django.core.urlresolvers import reverse
 from django.db import models
-from django.db.models.signals import m2m_changed
+from django.db.models.signals import m2m_changed, pre_save
 from django.db.models import CharField, F, Q
 from django.db.models.base import ModelBase
 from django.db.utils import DatabaseError
@@ -18,6 +20,7 @@
 from mezzanine.generic.fields import RatingField
 from mezzanine.pages.models import Page
 from mezzanine.utils.models import AdminThumbMixin, upload_to
+from mezzanine.utils.email import send_mail_template
 
 from cartridge.shop import fields, managers
 
@@ -305,6 +308,30 @@ def update_stock(self, quantity):
                 self.product.save()
 
 
+@receiver(pre_save, sender=ProductVariation,
+          dispatch_uid="wishlist_notifications_on_save")
+def wishlist_notifications_on_save(sender, instance, **kwargs):
+    if settings.SHOP_WISHLIST_NOTIFICATIONS is not True:
+        return
+    if instance.id:
+        productvariation = ProductVariation.objects.get(pk=instance.id)
+        old_stock = productvariation.num_in_stock
+        if (old_stock == 0) and (instance.num_in_stock > old_stock):
+            # Send email
+            email_from = settings.DEFAULT_FROM_EMAIL
+            wishlist = Wishlist.objects.filter(sku=productvariation.sku)
+            for item in wishlist:
+                email_to = item.user.email
+                subject = _("Notification from wishlist")
+                context = {
+                    "productvariation": productvariation,
+                    "user": item.user,
+                }
+                send_mail_template(subject, "email/wishlist_notification",
+                                   email_from, email_to, context,
+                                   fail_silently=settings.DEBUG)
+
+
 class Category(Page, RichText):
     """
     A category of products on the website.
@@ -843,3 +870,31 @@ def calculate(self, amount):
     class Meta:
         verbose_name = _("Discount code")
         verbose_name_plural = _("Discount codes")
+
+
+class Wishlist(models.Model):
+
+    user = models.ForeignKey(User)
+    sku = fields.SKUField()
+
+    objects = managers.WishlistManager()
+
+    class Meta:
+        unique_together = ('user', 'sku')
+        verbose_name = _("Wishlist item")
+        verbose_name_plural = _("Wishlist items")
+
+
+@receiver(user_logged_in, sender=User)
+def transfer_wishlist_data(sender, request, user, *args, **kwargs):
+    skus = getattr(request, "wishlist", [])
+    if not skus:
+        return
+    existed = (Wishlist.objects.filter(user=user, sku__in=skus)
+                               .values_list("sku", flat=True))
+    for sku in skus:
+        if sku not in existed:
+            wishlist = Wishlist()
+            wishlist.user = user
+            wishlist.sku = sku
+            wishlist.save()

cartridge/shop/templates/email/wishlist_notification.txt

@@ -0,0 +1,11 @@
+{% extends "email/base.txt" %}
+{% load shop_tags i18n %}
+
+{% block main %}
+{% trans "Dear" %} {{ user }},
+
+{% trans "This product is available for order" %}:
+
+{{ productvariation }}
+
+{% endblock %}

cartridge/shop/templates/shop/wishlist.html

@@ -11,7 +11,7 @@
 
 {% block main %}
 {% if error %}{{ error }}{% endif %}
-{% if request.wishlist %}
+{% if wishlist_items %}
 <table class="table table-striped wishlist">
 	{% for item in wishlist_items %}
 	<tr>

cartridge/shop/utils.py

@@ -48,6 +48,20 @@ def add_item(self, *args, **kwargs):
         self._request.session["cart"] = cart.id
 
 
+class CookieBackedWishlist(object):
+    """
+    A dummy wishlist object used for unauthenticated users, backed by cookie
+    storage.
+    """
+    def __init__(self, request):
+        super(CookieBackedWishlist, self).__init__()
+        self.request = request
+
+    def save(self, *args, **kwargs):
+        if self.sku not in self.request.wishlist:
+            self.request.wishlist.append(self.sku)
+
+
 def make_choices(choices):
     """
     Zips a list with itself for field choices.
@@ -113,3 +127,12 @@ def set_locale():
                 "configure the SHOP_CURRENCY_LOCALE setting in your settings "
                 "module.")
         raise ImproperlyConfigured(msg % currency_locale)
+
+
+def get_wishlist(request):
+    if request.user.is_authenticated():
+        from cartridge.shop.models import Wishlist
+        wishlist = Wishlist()
+    else:
+        wishlist = CookieBackedWishlist(request)
+    return wishlist

cartridge/shop/views.py

@@ -3,6 +3,7 @@
 from django.contrib.auth.decorators import login_required
 from django.contrib.messages import info
 from django.core.urlresolvers import get_callable, reverse
+from django.db import IntegrityError
 from django.http import Http404, HttpResponse
 from django.shortcuts import get_object_or_404, redirect
 from django.template import RequestContext
@@ -19,8 +20,8 @@
 from cartridge.shop import checkout
 from cartridge.shop.forms import AddProductForm, DiscountForm, CartItemFormSet
 from cartridge.shop.models import Product, ProductVariation, Order, OrderItem
-from cartridge.shop.models import DiscountCode
-from cartridge.shop.utils import recalculate_discount, sign
+from cartridge.shop.models import DiscountCode, Wishlist
+from cartridge.shop.utils import recalculate_discount, sign, get_wishlist
 
 
 # Set up checkout handlers.
@@ -60,13 +61,16 @@ def product(request, slug, template="shop/product.html"):
                 info(request, _("Item added to cart"))
                 return redirect("shop_cart")
             else:
-                skus = request.wishlist
-                sku = add_product_form.variation.sku
-                if sku not in skus:
-                    skus.append(sku)
-                info(request, _("Item added to wishlist"))
                 response = redirect("shop_wishlist")
-                set_cookie(response, "wishlist", ",".join(skus))
+                wishlist = get_wishlist(request)
+                wishlist.user = request.user
+                wishlist.sku = add_product_form.variation.sku
+                try:
+                    wishlist.save()
+                except IntegrityError:
+                    pass
+                set_cookie(response, "wishlist", ",".join(request.wishlist))
+                info(request, _("Item added to wishlist"))
                 return response
     context = {
         "product": product,
@@ -76,7 +80,8 @@ def product(request, slug, template="shop/product.html"):
         "variations_json": variations_json,
         "has_available_variations": any([v.has_price() for v in variations]),
         "related_products": product.related_products.published(
-                                                      for_user=request.user),
+            for_user=request.user
+        ),
         "add_product_form": add_product_form
     }
     return render(request, template, context)
@@ -110,15 +115,16 @@ def wishlist(request, template="shop/wishlist.html"):
             message = _("Item removed from wishlist")
             url = "shop_wishlist"
         sku = request.POST.get("sku")
-        if sku in skus:
-            skus.remove(sku)
+        if sku in request.wishlist:
+            Wishlist.objects.delete_for_request(sku, request)
         if not error:
             info(request, message)
             response = redirect(url)
-            set_cookie(response, "wishlist", ",".join(skus))
+            set_cookie(response, "wishlist", ",".join(request.wishlist))
             return response
 
     # Remove skus from the cookie that no longer exist.
+    skus = request.wishlist
     published_products = Product.objects.published(for_user=request.user)
     f = {"product__in": published_products, "sku__in": skus}
     wishlist = ProductVariation.objects.filter(**f).select_related(depth=1)