filter

The filter method is a part of the QuerySet class.

This method allows you to retrieve multiple instances of a model from the database based on the provided criteria.

Quick example

from models import Article

articles = Article.manager.filter(title='Hello World')

This would translate to the following SQL query:

SELECT * FROM articles WHERE title = 'Hello World';

Chain multiple filters

Because querysets are lazily evaluated, you can chain multiple filters together to create more complex queries.

from models import Article

query = Article.manager.filter(title='Hello World')

author = input('Enter author name: ')

if author != '':
    query = query.filter(author=author)

AND operator

The filter method supports the AND operator implicitly. When you provide multiple conditions to the filter method, it combines them using the AND operator.

This allows you to filter records based on multiple conditions that all need to be true.

Quick example

from models import Article

articles = Article.manager.filter(title='Hello World', author='John Doe')

This would translate to the following SQL query:

SELECT * FROM articles WHERE title = 'Hello World' AND author = 'John Doe';

IN operator

The filter method also supports the IN operator by adding the suffix __in to the field name.

This allows you to filter records based on a list of values.

Quick example

from models import Article

articles = Article.manager.filter(id__in=[1, 2, 3])

This would translate to the following SQL query:

SELECT * FROM articles WHERE id IN (1, 2, 3);

OR operator

The filter method supports the OR operator by using the Q object. When you provide multiple conditions to the Q object and combine them with the | operator, it translates to the OR operator in SQL.

This allows you to filter records based on multiple conditions where at least one needs to be true.

Quick example

from blazingapi.auth.models import User
from blazingapi.orm.query import Q

admin = User.manager.filter(Q(username="admin") | Q(username="root"))

This would translate to the following SQL query:

SELECT * FROM users WHERE username = 'admin' OR username = 'root';

LIMIT operator

The all and filter methods support limiting the number of results returned by using Python's list slicing syntax. This translates to the LIMIT clause in SQL.

This allows you to retrieve a specific number of records from the database.

Quick example

from models import Article

articles = Article.manager.all()[:10]

This would translate to the following SQL query:

SELECT * FROM articles LIMIT 10;

OFFSET operator

The all and filter methods support offsetting the results returned by using Python's list slicing syntax. This translates to the OFFSET clause in SQL.

This allows you to skip a specific number of records before starting to return the results from the database.

Quick example

from models import Article

articles = Article.manager.all()[10:]

This would translate to the following SQL query:

SELECT * FROM articles OFFSET 10;

The difference between the get method and the filter method is that the get method will return a single instance of the model, while the filter method will return a list of instances even if the number of rows is 1.