(ArgumentError) argument error - when trying to pass a list of values to a changeset

Question

I am trying to pass a list of values to a changeset and have following methods:

The schema and changeset method:

defmodule Pubcus.Country do

    use Pubcus.Web, :model

  schema "countries" do

    field :code, :string
    field :en, :string
    field :de, :string
    field :it, :string
    field :fr, :string

    timestamps

  end

  def changeset_all(model, list) when is_list(list) do

        list
        |> Enum.map(fn param -> changeset(model, param) end)

  end


  def changeset(model, params \\ %{}) do

        model
    |> cast(params, [:code, :en, :de, :it, :fr])
    |> validate_required([:code, :en])
    |> validate_length(:code, max: 2)
    |> unique_constraint(:code)

  end

end

Then the test:

defmodule Pubcus.CountryModelTest do

    use Pubcus.ModelCase

    alias Pubcus.Country

    @valid_attrs %{ code: "CH", en: "Switzerland", de: "Schweiz", it: "Svizzera", fr: "Suisse" }
    @invalid_attrs %{ code: "CHH" }

    @valid_attrs_list [ %{code: "CH", en: "Switzerland", de: "Schweiz", it: "Svizzera", fr: "Suisse"},
                                          %{code: "IT", en: "Italy", de: "Italien"},
                                          %{code: "FR", en: "Franche", de: "Frankreich"} ]

    test "a valid dataset" do

      changeset = Country.changeset(%Country{}, @valid_attrs)
      assert changeset.valid?

    end

    test "a invalid country code" do

      errors = errors_on(%Country{}, @invalid_attrs)
      assert {:code, "should be at most 2 character(s)"} in errors
      assert {:en, "can't be blank"} in errors

    end

    test "a valid list of countries" do

      changeset = Country.changeset_all(%Country{}, @valid_attrs_list)
      assert changeset.valid?

    end


end

When I test it, it shows me:

1) test a valid list of countries (Pubcus.CountryModelTest)
     test/models/country_model_test.exs:27
     ** (ArgumentError) argument error
     stacktrace:
       :erlang.apply([#Ecto.Changeset<action: nil, changes: %{code: "CH", de: "Schweiz", en: "Switzerland", fr: "Suisse", it: "Svizzera"}, errors: [], data: #Pubcus.Country<>, valid?: true>], :valid?, [])

What am I doing wrong?

Answer 1

The problem is that Country.changeset_all returns a list of Ecto.Changesets, not one Ecto.Changeset, so you can't do .valid? on that. You can iterate through the list and assert on each:

for changeset in Country.changeset_all(%Country{}, @valid_attrs_list) do
  assert changeset.valid?
end