- First ecommence project
“Let’s go over our models and their attributes:
name
- this attribute will be responsible for preserving titles of categories and products that we create. This field is set to be a
CharField, since we want it to store text value, which then translates into a VARCHAR value in our database. The maximum character count is set to 100.
slug
- This is a field intended to be used in URLs. A slug is a short label that contains only letters, numbers, underscores, or hyphens. We will use the slug field to build beautiful, SEO-friendly URLS for our e-commerce listings. Both, name and slug fields, are set to be unique, meaning Django will prevent multiple categories having the same name and slug fields.
category
- This field defines a many-to-one relationship, meaning that each product belongs to a specific category, and the category can contain any number of products. To keep track of the relationship between
CategoryandProductmodels, Django will actually create extra column in the Product table to store theCategoryid, under which a specific product belongs. This extra category id column makes it easy to, for example, retrieve all of the products for “a specific Category. As for related_name parameter, Django has a built-in syntax we can use, known as FOO_set, where FOO is a lowercased source model name. So, for our Category model, we can use category_set syntax to access all related Product instances. related_name parameter is entirely optional, but I prefer adding it to models, which then allows us to set the name of this reverse relationship explicitly.
image
- The image file. By default, images will be uploaded to the products folder.
description
- Field for storing product description. We are using TextField here instead of CharField, since we do not want to limit the description's length.
shu
- Scoville Heat Units (SHU) - since we will be selling hot sauces, we need a field to indicate, how hot the sauce is.
price
- this field uses Python’s decimal.Decimal type to store a fixed precision decimal number. The maximum number of digits (including the decimal places) is “set using the max_digits attribute and decimal places with decimal_places attribute. We use DecimalField instead of FloatField to avoid rounding issues.
available
- A Boolean value to indicate whether the product is available or not. If no value (True/False) is specified, a database record is created with the default value specified (True).”
- model metadata is “anything that’s not a field”. Note that adding Meta class to our models is optional.”
- Used to deal with images
@admin.register(Product)
class ProductAdmin(admin.ModelAdmin):
list_display =('name', 'category', 'slug', 'price', 'available')
list_filter = ('category', 'available')
list_editable = ('price', 'available')
prepopulated_fields = {'slug': ('name',)}
We added a couple of new attributes here. list_filter will enable us to filter products by their category and availability. When we create some products, you will notice a sidebar in the Products section very similar to the one in Users. We will use the list_editable attribute to set the fields that can be edited from the administration site's display page. This will allow us to edit “multiple rows at once. Any field in list_editable must also be present in the list_display attribute since only the displayed fields can be edited. While we are in the admin site, let’s add one more category to the portfolio (I will go with Extreme. Notice how the slug field is being filled in automatically).
“Django also comes with its own template system called Django template language (DTL), which enables us to customize, how the template is presented. It comes with four constructs:
-
{{variables}}- allow us to render a value from the context . They are surrounded by{{ and }} -
tags- provide arbitrary logic in the rendering process. They most often serve as a control structure in shape of “if” statement or a “for” loop. Tags are surrounded by {% and %} -
filters- transform the values of variables and tag arguments. They are surrounded by{{ and }}and come after variable we want to transform, separated by | (e.g.{{ review.created|date}}). They can also take arguments:{{ review.created|date:"Y-m-d"}} -
comments- look like this: {# this won't be rendered #}. A{% comment %}tag provides multi-line comments and has to be concluded by{% endcomment %}
“To pass our category_slug to product_list view, we will need to modify urls.py file residing in listings application to include another URL that will be responsible for passing slug to our view:
“This view is pretty straightforward. We provide category slug and product slug and fetch the corresponding product. We then pass it to our detail.html template, which we will build shortly. You might wonder where does category_id field comes from. Django, by default, adds it as the last column to our table to keep track of the relationship between category and product we defined in our models.py file.”
“We start by importing redirect function. Instead of simply using render function to show an updated detail page, we want to reroute a user back to the product detail page to avoid potentially performing the review submission twice if the user refreshed the page right after publishing the review. Then we import our Review model and ReviewForm that we just built.”
“In this new product_detail view, we differentiate between POST and GET requests. POST request will occur when a user submits a new review. If a user just visits the page, GET request will take place. In this case, we render the page within the product detail.html template, including ReviewForm().
When POST request occurs, we perform the following actions:
- Instantiate ReviewForm with submitted data.
- Check whether the form is valid. That’s where our MinValueValidator and MaxValueValidator do their part. This method validates data submitted in the form and returns True if all fields contain valid data. If any of the fields contain invalid data, we redirect the user back to the page without creating a Review object.
- If the form is valid, we retrieve validated data by accessing the .cleaned_data attribute of the form. This attribute is a dictionary of form fields and their values. This means we can access our submitted data using basic dictionary notations.
- Then we create a new Review object with data provided and save it to the database. Note that the author attribute defaults to "Anonymous" for now. Once we implement user accounts, we will modify this accordingly.”
- Finally, we redirect the user back to our product detail page. Our product_detail view then handles the HTTP request with GET request.method.”
{{ review_form.rating.0 }}
{{ review_form.rating.1 }}
{{ review_form.rating.2 }}
{{ review_form.rating.3 }}
{{ review_form.rating.4 }}
“It would be pretty handy to display the shopping cart link with the product cost up on the navbar, so it is visible and accessible from all of the pages. For this functionality, we will build a context processor to include the current cart in the request context, regardless of the view processing the request. Context processor is a Python function that takes the HttpRequest object as an argument and returns a dictionary that gets added to the request context. Context processors are useful, especially when we need to make something available globally to all templates”
The Order model is responsible for managing order information such as customer details, when was the order created and updated, the status of the order, optional note from customer, transport method, and related cost. For created and updated timestamps, we use slightly different arguments as they serve a different purpose. auto_now_add sets the field to now when the object is created, while auto_now sets the field to now every time the object is saved. Orders will be sorted based on the creation date in descending order from the latest. get_total_cost() method calculates the total cost of the purchased items and adds related transport cost to provide total order cost.”