Return :id from Ecto.Multi Transaction

Questions / Help
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1

I do have a problem regarding returning the created id from multi. Here is the sample code:

Ecto.Multi.new
|> Ecto.Multi.insert(:post, %Post{})
|> MyRepo.transaction

But all this does is return changes. How do I get the created id for it?

2

Ecto.Repo.transaction/2 will return an {:ok, changes} tuple where you can pattern match on the :post change to get the post and pull the id out. This should work:

Ecto.Multi.new
|> Ecto.Multi.insert(:post, %Post{})
|> MyRepo.transaction
|> case do
  {:ok, %{post: post} ->
    {:ok, post}
  {:error, _, reason, _} ->
     {:error, reason}
end

As a side note, Ecto.Multis are generally used to make multiple transactions which depend upon each other. If you are only inserting the one post you could use Repo.insert and just pass a changeset or struct.

2 Likes
3

Oh, right I forgot to pattern match the inside result that’s why I can’t output the post.id. Thanks @A-Legg