Get required_fields from changeset

Questions / Help
1

I read in Ecto.schema that we can get the fields and types of the fields by doing this:

Model.__ schema__(:fields)
Model.__ schema__(:types)

I have module attribute constant @required_fields and @optional_feilds.
Is there any way I can get required_fields and optional_fields from changeset or schema functions?

Thanks

2

No. But you can filter the values in Model.__ schema__(:fields) …

Or you can write your own functions or macros to return these fields

def required_fields do
  @required_fields
end

Then the filter would work like this

required_fields = Model.required_fields()
Model.__ schema__(:fields)
|> Enum.filter(fn field -> field in required_fields end)

EDIT: ignore me, see the answer below.

2 Likes
3

Required fields are stored in the :required field on the Changeset struct:

iex> changeset = Friends.Person.changeset(%Friends.Person{})
iex> changeset.required
[:first_name, :last_name]

you can check all other fields with e.g.:

iex> t Ecto.Changeset.t
@type t() :: %Ecto.Changeset{
        action: action(),
        changes: %{optional(atom()) => term()},
        constraints: [constraint()],
        data: Ecto.Schema.t() | map() | nil,
        empty_values: term(),
        errors: [{atom(), error()}],
        filters: %{optional(atom()) => term()},
        params: %{optional(String.t()) => term()} | nil,
        prepare: [(t() -> t())],
        repo: atom() | nil,
        repo_opts: Keyword.t(),
        required: [atom()],
        types: nil | %{optional(atom()) => Ecto.Type.t()},
        valid?: boolean(),
        validations: [{atom(), term()}]
      }
3 Likes
4

Thanks that helps. Didn’t know that