How to Merge QuerySets in Django

Table of Content

• How to Merge QuerySets in Django
• What you Should Know When Merging QuerySets in Django
• Wrap Off

When working with Django, there might be a need to merge two querysets and run operations on them.

Here's how to merge two or more querysets into a single queryset without losing the capabilities of performing filter, count, distinct, etc. operations.

Take the following models as an example:

class Show(models.Model):
    title = models.CharField(max_length=255)
    content = models.TextField(blank=True)
    category = models.ForeignKey(Category, related_name='shows')
    author = models.ForeignKey(User, related_name='shows')

class Channel(models.Model):
    name = models.CharField(max_length=30, unique=True)
    shows = models.ManyToManyField(Show)

Assuming you have a task to display all the shows posted in a specific Channel together with shows written by a User using the Category fiction.

Note that this User might have posted some shows in a different Channel:

channel = Channel.objects.get(name='Channel 15')
user = User.objects.get(username='nsikak')

fiction_shows = channel.shows.all()
nsikak_shows = user.shows.filter(category__name='comedy')

At this point, we have two different querysets.

One contains all the shows from a channel and the other contains all the shows from a user using the comedy category.

Here comes the task of merging them.

How to Merge QuerySets in Django

The querysets can be merged, using the pipe | operator:

Checkout the example below:

shows = comedy_shows | nsikak_stories  # merge querysets

And you still can perform queryset operations:

recent_shows = shows.distinct().order_by('-date')[:10]

What you Should Know When Merging QuerySets in Django

• Mering with the pipe operator | only works on querysets from the same model.

• You need to merge before performing slicing on either of the querysets.

Wrap Off

There you have it! I hope you found this post useful somehow.

If you have any questions or need clarification, feel free to reach out to me.

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