For better database integrity, it's common to define database constraints, telling some fields to be bound to fields of other database tables, making some fields unique or not null. For advanced database constraints, such as making the fields unique with a condition or setting specific conditions for the values of some fields, Django has special classes: UniqueConstraint and CheckConstraint. In this recipe, you will see a practical example of how to use them.
Adding database constraints
by Aidas Bendoraitis,
Jake Kronika
Django 3 Web Development Cookbook - Fourth Edition
- Title Page
- Copyright and Credits
- About Packt
- Contributors
- Preface
- Getting Started with Django 3.0
- Introduction
- Technical requirements
- Working with a virtual environment
- Creating a project file structure
- Handling project dependencies with pip
- Configuring settings for development, testing, staging, and production environments
- Defining relative paths in the settings
- Handling sensitive settings
- Including external dependencies in your project
- Setting up STATIC_URL dynamically
- Setting UTF-8 as the default encoding for the MySQL configuration
- Creating the Git ignore file
- Deleting Python-compiled files
- Respecting the import order in Python files
- Creating an app configuration
- Defining overwritable app settings
- Working with Docker containers for Django, Gunicorn, Nginx, and PostgreSQL
- Models and Database Structure
- Introduction
- Technical requirements
- Using model mixins
- Creating a model mixin with URL-related methods
- Creating a model mixin to handle creation and modification dates
- Creating a model mixin to take care of meta tags
- Creating a model mixin to handle generic relations
- Handling multilingual fields
- Working with model translation tables
- Avoiding circular dependencies
- Adding database constraints
- Using migrations
- Changing a foreign key to the many-to-many field
- Forms and Views
- Introduction
- Technical requirements
- Creating an app with CRUDL functions
- Saving the author of a model instance
- Uploading images
- Creating a form layout with custom templates
- Creating a form layout with django-crispy-forms
- Working with formsets
- Filtering object lists
- Managing paginated lists
- Composing class-based views
- Providing Open Graph and Twitter Card data
- Providing schema.org vocabularies
- Generating PDF documents
- Implementing a multilingual search with Haystack and Whoosh
- Implementing a multilingual search with Elasticsearch DSL
- Templates and JavaScript
- Introduction
- Technical requirements
- Arranging the base.html template
- Using Django Sekizai
- Exposing settings in JavaScript
- Using HTML5 data attributes
- Providing responsive images
- Implementing a continuous scrolling
- Opening object details in a modal dialog
- Implementing the Like widget
- Uploading images via Ajax
- Custom Template Filters and Tags
- Introduction
- Technical requirements
- Following conventions for your own template filters and tags
- Creating a template filter to show how many days have passed since a post was published
- Creating a template filter to extract the first media object
- Creating a template filter to humanize URLs
- Creating a template tag to include a template, if it exists
- Creating a template tag to load a QuerySet in a template
- Creating a template tag to parse content as a template
- Creating template tags to modify request query parameters
- Model Administration
- Security and Performance
- Introduction
- Technical requirements
- Making forms secure from Cross-Site Request Forgery (CSRF)
- Making requests secure with Content Security Policy (CSP)
- Using django-admin-honeypot
- Implementing password validation
- Downloading authorized files
- Adding a dynamic watermark to images
- Authenticating with Auth0
- Caching the method return value
- Using Memcached to cache Django views
- Using Redis to cache Django views
- Hierarchical Structures
- Introduction
- Technical requirements
- Creating hierarchical categories with django-mptt
- Creating a category administration interface with django-mptt-admin
- Rendering categories in a template with django-mptt
- Using a single selection field to choose a category in forms with django-mptt
- Using a checkbox list to choose multiple categories in forms with django-mptt
- Creating hierarchical categories with django-treebeard
- Creating a basic category administration interface with django-treebeard
- Importing and Exporting Data
- Introduction
- Technical requirements
- Importing data from a local CSV file
- Importing data from a local Excel file
- Importing data from an external JSON file
- Importing data from an external XML file
- Preparing paginated sitemaps for search engines
- Creating filterable RSS feeds
- Using Django REST framework to create an API
- Bells and Whistles
- Introduction
- Technical requirements
- Using the Django shell
- Using database query expressions
- Monkey patching the slugify() function for better internationalization support
- Toggling the Debug toolbar
- Using ThreadLocalMiddleware
- Using signals to notify administrators about new entries
- Checking for missing settings
- Testing
- Deployment
- Introduction
- Technical requirements
- Releasing a reusable Django app
- Deploying on Apache with mod_wsgi for the staging environment
- Deploying on Apache with mod_wsgi for the production environment
- Deploying on Nginx and Gunicorn for the staging environment
- Deploying on Nginx and Gunicorn for the production environment
- Maintenance
- Other Books You May Enjoy
Adding database constraints
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