Ecto - Updating Nested (Polymorphic) Associations

Question

How to update a model with nested communication (using [Elixir, Phoenix, Ecto])?

I tried the following to process it as part of its parent update without success (using blog> platformatec as inspiration).

Models:

schema "user" do has_one :address, {"users_addresses", MyApp.Address}, foreign_key: :assoc_id end @required_fields ~w(address) ------ # Materialized in users_addresses table schema "abstract table: addresses" do field :assoc_id, :integer field :street_address, :string end 

Request (PATCH):

 { "user" => { "address" => { "street_address" => "1234" } } } 

Controller:

 def update(conn, %{"id" => id, "user" => params}) do user = MyApp.Repo.get(User, id) |> MyApp.Repo.preload [:address] if is_nil(user) do send_resp(conn, 404, "") else changeset = User.changeset(user, params) if changeset.valid? do case MyApp.Repo.update(changeset) do {:ok, model} -> send_resp(conn, 204, "") {:error, changeset} -> conn |> put_status(:unprocessable_entity) |> render(MyApp.ChangesetView, "error.json", changeset: changeset) end else conn |> put_status(:unprocessable_entity) |> render(MyApp.ChangesetView, "error.json", changeset: changeset) end end end 

Changes (from logs):

 %Ecto.Changeset{action: nil, changes: %{address: %Ecto.Changeset{action: :insert, changes: %{street_address: "1234"}, constraints: [], .... model: %MyApp.User{__meta__: #Ecto.Schema.Metadata<:loaded>, address: %MyApp.Address{__meta__: #Ecto.Schema.Metadata<:loaded>, assoc_id: 1229, id: 308, street_address: "41423 Jakubowski Village" .... } } } 

Error: Fixed with Ecto v1.0.3 or later

 ** (exit) an exception was raised: ** (Postgrex.Error) ERROR (undefined_table): relation "abstract table: addresses" does not exist (ecto) lib/ecto/adapters/sql.ex:479: Ecto.Adapters.SQL.model/6 (ecto) lib/ecto/repo/model.ex:219: Ecto.Repo.Model.apply/4 (ecto) lib/ecto/repo/model.ex:71: anonymous fn/10 in Ecto.Repo.Model.insert/4 (ecto) lib/ecto/repo/model.ex:340: anonymous fn/3 in Ecto.Repo.Model.wrap_in_transaction/8 (ecto) lib/ecto/adapters/sql.ex:531: anonymous fn/10 in Ecto.Adapters.SQL.transaction/3 (ecto) lib/ecto/pool.ex:262: Ecto.Pool.inner_transaction/3 (ecto) lib/ecto/adapters/sql.ex:534: Ecto.Adapters.SQL.transaction/3 (ecto) lib/ecto/association.ex:368: Ecto.Association.Has.on_repo_action/7 

Answer 1

(Postgrex.Error) ERROR (undefined_table): relation "abstract table: addresses" does not exist was caused by an error that should be fixed in Ecto v1.0.3 or later.

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In the above code, there is no identifier for the address, without this Ecto will insert a new resource instead of updating an existing one.

Request (PATCH):

 { "user" => { "address" => { "id" => 4, "street_address" => "1234" } } } 

The new controller code, including some of JoseValims, has suggested improvements:

  def update(conn, %{"id" => id, "user" => params}) do user = MyApp.Repo.get!(User, id) |> MyApp.Repo.preload [:address changeset = User.changeset(user, params) case MyApp.Repo.update(changeset) do {:ok, model} -> send_resp(conn, 204, "") {:error, changeset} -> conn |> put_status(:unprocessable_entity) |> render(MyApp.ChangesetView, "error.json", changeset: changeset) end end 

Or, in this situation, since the address is required and has_one , an identifier can be added on the server side:

  def update(conn, %{"id" => id, "user" => params}) do user = MyApp.Repo.get!(User, id) |> MyApp.Repo.preload [:address] address = params["address"] address = Map.put address, "id", user.address.id params = Map.put params, "address", address changeset = User.changeset(user, params) case MyApp.Repo.update(changeset) do {:ok, model} -> send_resp(conn, 204, "") {:error, changeset} -> conn |> put_status(:unprocessable_entity) |> render(MyApp.ChangesetView, "error.json", changeset: changeset) end end