Delete a grandchild association in a Ecto.Changeset

Questions / Help
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8

I mean working with a schema which is actually stored in the database, ie: if you change the Foo.foo value from “stored_value_in_db” to “new_value”, and later you delete_bar, when you apply_changes you lose the current changes. In this case, if you Repo.update(changeset) the Foo.foo value won’t be updated. I did something similar to the following to solve this problem (I didn’t try this code):

  def handle_event("delete_bar", index, socket) do
    bars = Ecto.Changeset.get_change(socket.assigns.changeset, :bars, [])
           |> List.delete_at(index)
    {:noreply, assign(socket, changeset: Ecto.Changeset.change(bars)}
  end

  def handle_event("delete_baz", indexes, socket) do
    changeset = socket.assigns.changeset
    [bar_index, baz_index] = indexes |> String.split("-") |> Enum.map(&String.to_integer/1)
    bars = Ecto.Changeset.get_change(socket.assigns.changeset, :bars, [])
           |> List.update_at(bar_index, fn bar_ch ->
       bazs = Ecto.Changeset.get_change(bar_ch, :bazs, [])
              |> List.delete_at(baz_index)
       Ecto.Changeset.change(bar_ch, bazs: bazs)
    end)
    {:noreply, assign(socket, changeset: Ecto.Changeset.change(changeset, bars: bars))}
  end

This way I avoid to apply_changes to don’t lose the changes