Django: Homepage

from: https://developer.mozilla.org/en-US/docs/Learn/Server-side/Django/Home_page

Data flow and handling HTTP requests and responses

• URL mappers direct URLs and information to view functions
• View functions retrieve data from models and render HTML
• Templates: Define HTML for displaying data.

Creating the index page

catalog/

• index page
• includes counts of records in the database

URL mapping

locallibrary/urls.py

• Processes URLs starting with catalog/
• catalog.urls processes the substring

The import function django.urls.include() splits the URL string and sends the substring to the URLconf module.

/catalog/urls.py is a placeholder for the URLConf module

path()

• Defines a URL pattern and associates it with a view function.
• The name parameter is a unique identifier for URL mapping.
• Use the name parameter to reverse the URL mapper and dynamically generate a URL that directs to a resource.
• Reversed URL mapping is more robust than hard-coded links.
• Use the name parameter to create links

View

A view function

• Handles an HTTP request
• Retrieves necessary data from the database
• Generates an HTML page using a template to display the data

The first line in catalog/views.py imports render() to generate an HTML file.

The next line imports the model classes used to access data in views.

The view function 'index'

• Fetches the number of records using objects.all() on the model classes.
• Retrieves a collection of BookInstance objects where the status field is set to 'a' for available
• Calls the render() function to create an HTML page a return the page as a response.

The context variable is a dictionary, containing the placeholder data.

Template

• A template defines the structure a file, such as an HTML page
• Use placeholders for content

In the index view from 'locallibrary/catalog/views.py', the render() function will expect to find /django-locallibrary-tutorial/catalog/templates/index.html or return an error.

Extending templates

Declare a base template and extend it to replace different parts for each specific page.

Template tags

• loop through lists
• conditional operations

Template syntax

• Reference variables from the view
• Use filters to format variables

When defining a template specify the base template using the extends template tag. Then declare sections from the template to be replaced.

Our base template is /django-locallibrary-tutorial/catalog/templates/base_generic.html

The base template references /django-locallibrary-tutorial/catalog/static/css/styles.css that provides additional styling.

The index template

/django-locallibrary-tutorial/catalog/templates/index.html starts by extending the base template and then customizes the default content block specific to the template's needs.

Template variables

• Placeholders for the information from the view
• Variables are enclosed with double brace handlebars

The names of the variables correspond to the keys provided in the context dictionary within the view's render() function.

Referencing static files in templates

https://docs.djangoproject.com/en/5.0/howto/static-files/

Static resources include JavaScript, CSS, and images. You can specify the location in your templates relative to the STATIC_URL global setting. The default value of STATIC_URL is set to '/static/'. You can change it and host resources on a content delivery network.

To reference static files in a template, initially load the static template tag to include the template library. After that, use the static tag to provide the relative path to the desired file.

Linking to URLs

The base template uses the url template tag.

This tag

• Takes the name of a path() function called in urls.py
• Accepts the values for arguments the associated view will receive
• Returns a URL used to link to the resource

Configuring where to find the templates

https://docs.djangoproject.com/en/5.0/topics/templates/

Django searches for templates specified in the TEMPLATES object in the settings

In settings.py 'APP_DIRS': True instructs Django to look for templates within a "templates" subdirectory inside each app of the project. You can also specify particular directories for Django to search by setting 'DIRS': [].

View my commits here:

https://github.com/Samuel-Lubliner/local-library-django-tutorial/commit/3727b04dd95abbdf4e6d974fb0da10e17b16176c

See:

Writing your first Django app, part 3: Views and Templates
URL dispatcher
View functions
Templates
Managing static files
Django shortcut functions