How to Cast a CharField to an Integer in Django ORM Queries?

Casting Char to Integer in Django ORM Queries

When querying with Django Object-Relational Mapper (ORM), it might be necessary to cast a character field (CharField) to an integer. This can be achieved using the Cast function, introduced in Django 1.10.

In the given query:

<code class="sql">select student_id from students where student_id like "%97318%" order by CAST(student_id as UNSIGNED) desc;</code>

The student_id field, being a CharField, needs to be cast to an integer (INT) for sorting. To perform this operation in Django ORM, use the following syntax:

<code class="python">from django.db.models import Cast
from django.db.models.functions import Cast

students.objects.annotate(
    student_id_int=Cast('student_id', 'INT')  # Casting CharField to integer
).order_by('-student_id_int')</code>

The Cast function takes two arguments:

• The field name to be cast.
• The data type to cast the field to.

In this example, we cast the student_id field to INT, effectively converting it to an integer for the sorting operation. This allows for accurate sorting of the results using the order_by clause.

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