Adding id to assocs when inserting changeset

Questions / Help
1

Hi, I have an Order model that has_many OrderItem.

I want to be able to insert an order and its order items with a single changeset:

alias MyApp.Orders.Order
alias MyApp.Orders.OrderItem

order = %{
  name: "Order 1",
  order_items: [
    %{
      sku_id: 1,
      quantity: 5
    },
    %{
      sku_id: 2,
      quantity: 10
    }
  ]
}

%Order{}
|> Order.changeset(order)
|> MyApp.Repo.insert!()

But Ecto points that order_items must have an order_id.

How can I generate the IDs properly?

Perhaps I am doing it wrong and should use a Multi?

2

What you have is normally fine, but it requires that your Order.changeset function has some stuff to make it work. Can you show what you have for that function?

3

Seconded! I’d check for a missing |> cast_assoc(:order_items).

Here’s an example from the Ecto Associations guide for reference:

Inserting parent and child records together

…

Using external data

# Params represent data from a form, API, CLI, etc
params = %{
  "title" => "Shawshank Redemption",
  "release_date" => "1994-10-14",
  "characters" =>
    [
      %{"name" => "Andy Dufresne", "age" => "50"},
      %{"name" => "Red", "age" => "60"}
    ]
}

%Movie{}
|> cast(params, [:title, :release_date])
|> cast_assoc(:characters)
|> Repo.insert()
1 Like
4

Check your OrderItem.changeset function - it shouldn’t have validate_required on order_id, but this result suggests that it does.

5

Thanks @benwilson512 and @al2o3cr

Removing validate_required from the changeset did it.

6

It also may be worth reviewing the assoc_constraint/3 and foreign_key_constraint/3 to see if that was what you actually want.

1 Like