5. Catalog¶
The catalog presumably is that part, where customers of our e-commerce site spend the most time. Often it even makes sense, to start the Catalog List View on the main landing page.
In this documentation we presume that categories of products are built up using specially tagged CMS pages in combination with a djangoCMS apphook. This works perfectly well for most implementation, but some sites may require categories implemented independently of the CMS.
Using an external django-SHOP plugin for managing categories is a very conceivable solution, and we will see separate implementations for this feature request. Using such an external category plugin can make sense, if this e-commerce site requires hundreds of hierarchical levels and/or these categories require a set of attributes which are not available in CMS pages. If you are going to use externally implemented categories, please refer to their documentation, since here we proceed using CMS pages as categories.
A nice aspect of django-SHOP is, that it doesn’t require the programmer to write any special
Django Views in order to render the catalog. Instead all merchant dependent business logic goes
into a serializer, which in this documentation is referred as ProductSerializer
.
5.1. Catalog List View¶
In this documentation, the catalog list view is implemented as a django-CMS page. Depending on whether the e-commerce aspect of that site is the most prominent part or just a niche of the CMS, select an appropriate location in the page tree and create a new page. This will become the root of our catalog list.
But first we must Create the CatalogListApp.
5.1.1. Create the CatalogListApp
¶
To retrieve a list of product models, the Catalog List View requires a djangoCMS apphook. This
CatalogListApp
must be added into a file named cms_apps.py
and located in the root folder
of the merchant’s project:
from cms.apphook_pool import apphook_pool
from shop.cms_apphooks import CatalogListCMSApp
class CatalogListApp(CatalogListCMSApp):
def get_urls(self, page=None, language=None, **kwargs):
return ['myshop.urls.products']
apphook_pool.register(CatalogListApp)
as all apphooks, it requires a file defining its urlpatterns:
from django.conf.urls import url
from shop.views.catalog import ProductListView
urlpatterns = [
url(r'^$', ProductListView.as_view()),
# other patterns
]
By default the ProductListView
renders the catalog list of products assigned to the current CMS
page. In this example, only model attributes for fields declared in the default
ProductSummarySerializer
are available in the render context for the used CMS template, as well
as for a representation in JSON suitable for client side rendered list views. This allows us to
reuse this Django View (ProductListView
) whenever the catalog list switches into infinite scroll
mode, where it only requires the product’s summary, composed of plain old JavaScript objects.
5.1.1.1. Customized Product Serializer¶
In case we need Additional Product Serializer Fields, let’s add them to this class using the serializer fields from the Django RESTFramework library. This can be useful for product serializers which shall provide more information on our catalog list view.
For this customized serializer, we normally only require a few attributes from our model, therefore we can write it as:
from shop.serializers.bases import ProductSerializer
class CustomizedProductSerializer(ProductSerializer):
class Meta:
model = Product
fields = [all-the-fields-required-for-the-list-view]
Additionally, we have to rewrite the URL pattern from above as:
from django.conf.urls import url
from shop.views.catalog import ProductListView
from myshop.serializers import CustomizedProductSerializer
urlpatterns = [
url(ProductListView.as_view(
serializer_class=CustomizedProductSerializer,
)),
# other patterns
]
Here the CustomizedProductSerializer
is used to create a more specialized representation of our
product model.
5.1.2. Add the Catalog to the CMS¶
In the page list editor of django-CMS, create a new page at an appropriate location of the page tree. As the page title and slug we should use something describing our product catalog in a way, both meaningful to the customers as well as to search engines.
Next, we change into Advanced Settings mode.
As a template we use one with a big placeholder, since it must display our list of products.
As Application, select “Catalog List”. This selects the apphook we created in the previous section.
Then we save the page, change into Structure mode and locate the placeholder named Main Content. Add a Container plugin, followed by a Row and then a Column plugin. As the child of this column choose the Catalog List View plugin from section Shop.
Finally we publish the page. If we have assigned products to that CMS page, they should be rendered now.
5.2. Catalog Detail View¶
The product’s detail pages are the only ones we typically do not control with django-CMS placeholders. This is because we often have thousands of products and creating a CMS page for each of them, would be kind of overkill. It only makes sense for shops selling up to a dozen of different products.
Therefore, the template used to render the products’s detail view is selected automatically by the
ProductRetrieveView
[1] following these rules:
- look for a template named
<myshop>/catalog/<product-model-name>-detail.html
[2] [3], otherwise - look for a template named
<myshop>/catalog/product-detail.html
[2], otherwise - use the template
shop/catalog/product-detail.html
.
[1] | This is the View class responsible for rendering the product’s detail view. |
[2] | (1, 2) <myshop> is the app label of the project in lowercase. |
[3] | <product-model-name> is the class name of the product model in lowercase. |
5.2.1. Use CMS Placeholders on Detail View¶
If we require CMS functionality for each product’s detail page, its quite simple to achieve. To the
class implementing our product model, add a djangoCMS Placeholder field named placeholder
.
Then add the templatetag {% render_placeholder product.placeholder %}
to the template
implementing the detail view of our product. This placeholder then shall be used to add arbitrary
content to the product’s detail page. This for instance can be an additional text paragraphs,
some images, a carousel or whatever is available from the djangoCMS plugin system.
5.2.2. Route requests on Detail View¶
The ProductsListApp
, which we previously have registered into django-CMS, is able to route
requests on all of its sub-URLs. This is done by expanding the current list of urlpatterns:
from django.conf.urls import url
from shop.views.catalog import ProductRetrieveView
urlpatterns = [
# previous patterns
url(r'^(?P<slug>[\w-]+)$', ProductRetrieveView.as_view()),
# more patterns
]
If we need additional business logic regarding our product, we can create a customized serializer
class, named for instance CustomizedProductDetailSerializer
. This class then may access the
various attributes of our product model, recombine them and/or merge them into a serializable
representation, as described in Customized Product Serializer.
Additionally, we have to rewrite the URL pattern from above as:
from myshop.serializers import CustomizedProductDetailSerializer
urlpatterns = [
# previous patterns
url(r'^(?P<slug>[\w-]+)$', ProductRetrieveView.as_view(
serializer_class=CustomizedProductDetailSerializer,
)),
# more patterns
]
5.2.2.1. Additional Product Serializer Fields¶
Sometimes such a serializer field shall return a HTML snippet; this for instance is required for
image source (<img src="..." />
) tags, which must thumbnailed by the server when rendered using
the appropriate templatetags from the easythumbnail library. For these use cases add a field
of type media = SerializerMethodField()
with an appropriate method get_media()
to our
serializer class. This method then may forward the given product to a the built-in renderer:
class ProductDetailSerializer(BaseProductDetailSerializer):
# other attributes
def get_media(self, product):
return self.render_html(product, 'media')
This HTML renderer method looks up for a template following these rules:
- look for a template named
<myshop>/product/catalog-<product-model-name>-<second-argument>.html
[4] [5] [6], otherwise - look for a template named
<myshop>/product/catalog-product-<second-argument>.html
[4] [6], otherwise - use the template
shop/product/catalog-product-<second-argument>.html
[6].
[4] | (1, 2) <myshop> is the app label of the project in lowercase. |
[5] | <product-model-name> is the class name of the product model in lowercase. |
[6] | (1, 2, 3) <field-name> is the attribute name of the just declared field in lowercase. |
5.2.3. Emulate Categories¶
Since we want to use CMS pages to emulate categories, the product model must declare a relationship
between the CMS pages and itself. This usually is done by adding a Many-to-Many field named
cms_pages
to our Product model.
As we work with deferred models, we can not use the mapping table, which normally is generated
automatically for Many-to-Many fields by the Django framework. Instead, this mapping table must
be created manually and referenced using the though
parameter, when declaring the field:
from shop.models.product import BaseProductManager, BaseProduct
from shop.models.related import BaseProductPage
class ProductPage(BaseProductPage):
"""Materialize many-to-many relation with CMS pages"""
class Product(BaseProduct):
# other model fields
cms_pages = models.ManyToManyField(
'cms.Page',
through=ProductPage
)
objects = ProductManager()
In this example the class ProductPage
is responsible for storing the mapping information
between our Product objects and the CMS pages.
5.2.3.1. Admin Integration¶
To simplify the declaration of the admin backend used to manage our Product model, django-SHOP is shipped with a special mixin class, which shall be added to the product’s admin class:
from django.contrib import admin
from shop.admin.product import CMSPageAsCategoryMixin
from myshop.models import Product
@admin.register(Product)
class ProductAdmin(CMSPageAsCategoryMixin, admin.ModelAdmin):
fields = [
'product_name', 'slug', 'product_code',
'unit_price', 'active', 'description'
]
# other admin declarations
This then adds a horizontal filter widget to the product models. Here the merchant must select each CMS page, where the currently edited product shall appear on.
If we are using the method render_html()
to render HTML snippets, these are cached by
django-SHOP, if caching is configured and enabled for that project. Caching these snippets is
highly recommended and gives a noticeable performance boost, specially while rendering catalog list
views.
Since we would have to wait until they expire naturally by reaching their expire time,
django-SHOP offers a mixin class to be added to the Product admin class, to expire all HTML
snippets of a product altogether, whenever a product in saved in the backend. Simply add
shop.admin.product.InvalidateProductCacheMixin
to the ProductAdmin
class described
above.
Note
Due to the way keys are handled in many caching systems, the InvalidateProductCacheMixin
only makes sense if used in combination with the redis_cache backend.