There are a few ways.

1. Use Nested Changesets
2. Insert each item individually in a transaction. (You would need to insert the user first so you have it’s id, then each article).
3. Use an EctoMulti.

The mutli is the same idea as 2 just a different way to do it.

If the user exists already you can upsert the user instead.

For 1 you can either do something like this:

Ecto.Changeset.cast(%User{}, changes, [:name])
|> Ecto.Changeset.cast_assoc(:articles)

Read more about cast assoc here https://link.medium.com/ZVBaeIrqM8

And check out the docs here https://hexdocs.pm/ecto/Ecto.Changeset.html

I want to use changeset; I don’t really see a reason to go for the 2. or 3. suggestion here.

Giving a list of IDs won’t work for cast_assoc (e.g. [5, 9, 18]). This is what is sent from Absinthe.

I’m not sure how to best solve this problem.