How to make a Union of two queries using Django Filter

Question

I was racking my brain to do union of two darlings using Django Filter and I ended up doing it on hand (Model.objects.raw("SELECT....")).

How could I union with Django’s ORM?

Note: I have 2 different tables with some common fields.

Table1

• table1_id
• name
• Description
• created_at
• user_id

Table2

• table2_id
• name
• Description
• created_at
• user_id

The relationship I want to maintain is between user_id. I want to put these records together and sort through created_at.

Answer 1

Depending on the type of relationship you are looking for, this can help you:

Table1.objects.filter(user_id__in=[x.user_id for x in Table2.objects.all()]).order_by('created_at')

Anyway, you can test the SQL equivalent of any Django query as follows:

query_aleatoria = Table1.objects.filter(description__contains='abacaxi')
print(query_aleatoria.query) # considerando python 3+

Edit:

I suggest you review your database structure, this user_id It seems to me a good candidate for foreign key, in which case the query would be easier. If you could include your relational model in your question, it would be of great help.

Answer 2

qs1 = Table1.objects.values("user_id", "created_at")
qs2 = Table2.objects.values("user_id", "created_at")
qs1.union(qs2).order_by("created_at")

https://docs.djangoproject.com/en/3.0/ref/models/querysets/#Union

Answer 3

Another way I found to make it work is by using the chain.

from itertools import chain

query1 = Blog1.objects.all()
query2 = Blog2.objects.all()

posts = list( chain(query1, query2) )