@spec options_for([map()], atom() | (map() -> term())) :: [{term(), term()}]

Generates {label, value} tuples for a list of maps or structs to be used in dropdowns.

Labels and values may be field names or unary functions. The value defaults to the :id field.

Use case and result

Use a display field as the label and each record's :id as the submitted value:

iex> users = [%{id: 1, name: "Alice"}, %{id: 2, name: "Bob"}]
iex> JediHelpers.FormHelpers.options_for(users, :name)
[{"Alice", 1}, {"Bob", 2}]

iex> users = [%{id: 1, name: "Alice"}, %{id: 2, name: "Bob"}]
iex> JediHelpers.FormHelpers.options_for(users, &String.upcase(&1.name), :id)
[{"ALICE", 1}, {"BOB", 2}]

The result can be passed directly to a Phoenix <.input type="select"> options attribute. Raises ArgumentError when an item is not a map or when a selector is invalid, and KeyError when a selected field is absent.

@spec options_for([map()], atom() | (map() -> term()), atom() | (map() -> term())) ::
  [{term(), term()}]

Generates option tuples using configurable label and value selectors.

Each selector can be an atom naming a map field or a unary function. This is useful when a select submits a slug instead of an ID or needs a composite label.

Use case and result

iex> users = [
...>   %{id: 1, first_name: "Leia", last_name: "Organa", slug: "leia"},
...>   %{id: 2, first_name: "Luke", last_name: "Skywalker", slug: "luke"}
...> ]
iex> JediHelpers.FormHelpers.options_for(
...>   users,
...>   &"#{&1.last_name}, #{&1.first_name}",
...>   :slug
...> )
[{"Organa, Leia", "leia"}, {"Skywalker, Luke", "luke"}]