How to Achieve MySQL\'s GROUP_CONCAT Functionality in Django?

Django's Equivalent to MySQL's GROUP_CONCAT

In Django, GROUP_CONCAT is not built-in, but it can be emulated using a custom Aggregate Function.

Creating a Custom Aggregate Function

To create a custom Aggregate Function for GROUP_CONCAT, follow these steps:

from django.db.models import Aggregate

class Concat(Aggregate):
    function = 'GROUP_CONCAT'
    template = '%(function)s(%(distinct)s%(expressions)s)'

    def __init__(self, expression, distinct=False, **extra):
        super(Concat, self).__init__(
            expression,
            distinct='DISTINCT ' if distinct else '',
            output_field=CharField(),
            **extra)

This class defines the GROUP_CONCAT function and its behavior.

Using the Custom Aggregate Function

To use your custom Aggregate Function, simply include it in your query as follows:

query_set = Fruits.objects.values('type').annotate(count=Count('type'),
                       name=Concat('name')).order_by('-count')

This will return a QuerySet with the desired results:

apple, 2, "fuji,mac"
orange, 1, "navel"

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