Course Content

Django ORM Ninja: Advanced Techniques for Developers

1. Introduction to Django ORM

Introduction to the Course Introduction to the ORM Start a New Project Initialize a New Project

2. Models, datatypes, and fields

Defining The First Model Field Data Types Define Other Models Migrations Admin Interface

3. Queries

Create Query Retrieve Query Lazy Queries Ordering and Slicing Updating Deleting

4. Relations

Many-to-One ForeignKey Arguments One-to-One Many-to-Many

5. Complex Queries

Field Lookups Q and F Objects Aggregations Annotations Minimazing Database Hints

6. Advanced

Class Meta Constrains Transactions Basics User Model

Django ORM Ninja: Advanced Techniques for Developers

Annotations

Annotation in Django ORM allows you to attach additional information to each object in a QuerySet. It's a powerful feature for augmenting the results of queries with calculated values, which can be aggregates computed over related objects or values derived from model fields.

Basic Annotation

Example 1:

Assume each Book has a pages field. This annotates each genre with the total number of pages of all books within that genre.

Example 2:

Assume each Book has a rating field.

Adds an average rating for the books written by each author.

Advanced Annotation Use Cases

Example 1:

Assume each Book has a publication_date field.

Counts how many books each author published per year.

Example 2:

Finds the most recently published book for each genre.

Annotation with Filters

Example 1:

Counts the number of fantasy books written by each author.

1. What is the primary purpose of annotation in Django ORM?

2. What does the following annotation query accomplish?

What is the primary purpose of annotation in Django ORM?

Select the correct answer

To modify database structure.

To delete records from the database.

To attach additional information to each object in a QuerySet.

To create new database tables.

What does the following annotation query accomplish?

Select the correct answer

It counts how many books each author published per year.

It finds the publication year of the oldest book for each author.

It calculates the average publication year of books for each author.

It lists all authors who have published books in a specific year.

Everything was clear?

Section 5. Chapter 4

Course Content

Django ORM Ninja: Advanced Techniques for Developers

1. Introduction to Django ORM

Introduction to the Course Introduction to the ORM Start a New Project Initialize a New Project

2. Models, datatypes, and fields

Defining The First Model Field Data Types Define Other Models Migrations Admin Interface

3. Queries

Create Query Retrieve Query Lazy Queries Ordering and Slicing Updating Deleting

4. Relations

Many-to-One ForeignKey Arguments One-to-One Many-to-Many

5. Complex Queries

Field Lookups Q and F Objects Aggregations Annotations Minimazing Database Hints

6. Advanced

Class Meta Constrains Transactions Basics User Model

Django ORM Ninja: Advanced Techniques for Developers

Annotations

Annotation in Django ORM allows you to attach additional information to each object in a QuerySet. It's a powerful feature for augmenting the results of queries with calculated values, which can be aggregates computed over related objects or values derived from model fields.

Basic Annotation

Example 1:

Assume each Book has a pages field. This annotates each genre with the total number of pages of all books within that genre.

Example 2:

Assume each Book has a rating field.

Adds an average rating for the books written by each author.

Advanced Annotation Use Cases

Example 1:

Assume each Book has a publication_date field.

Counts how many books each author published per year.

Example 2:

Finds the most recently published book for each genre.

Annotation with Filters

Example 1:

Counts the number of fantasy books written by each author.

1. What is the primary purpose of annotation in Django ORM?

2. What does the following annotation query accomplish?

What is the primary purpose of annotation in Django ORM?

Select the correct answer

To modify database structure.

To delete records from the database.

To attach additional information to each object in a QuerySet.

To create new database tables.

What does the following annotation query accomplish?

Select the correct answer

It counts how many books each author published per year.

It finds the publication year of the oldest book for each author.

It calculates the average publication year of books for each author.

It lists all authors who have published books in a specific year.

Everything was clear?

Section 5. Chapter 4

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