This module generates a :select field with options downloaded from Repo.

Example of use for Article with one Category:

schema "articles" do
  belongs_to :category, App.Category
end

form
|> add(:category_id, Formex.Ecto.CustomField.SelectAssoc, label: "Category")

Formex will find out that :category_id refers to App.Category schema and download all rows from Repo ordered by name.

If you are using :without_choices option (from Formex.Field.create_field/3), you don’t need to implement :choice_label_provider, this module will do it for you.

Options

• choice_label - controls the content of <option>. May be the name of a field or a function. Example of use:

  form
  |> add(:article_id, SelectAssoc, label: "Article", choice_label: :title)

  form
  |> add(:user_id, SelectAssoc, label: "User", choice_label: fn user ->
    user.first_name<>" "<>user.last_name
  end)

• query - an additional query that filters the choices list. Example of use:

  form
  |> add(:user_id, SelectAssoc, query: fn query ->
    from e in query,
      where: e.fired == false
  end)

• group_by - wraps <option>’s in <optgroup>’s. May be :field_name, :assoc_name or [:assoc_name, :field_name]

  Example of use:

  schema "users" do
    field :first_name, :string
    field :last_name, :string
    belongs_to :department, App.Department
  end

  schema "departments" do
    field :name, :string
    field :description, :string
  end

  Group by last name of user:

  form
  |> add(:user_id, SelectAssoc, group_by: :last_name)

  Group by department, by :name (default) field:

  form
  |> add(:user_id, SelectAssoc, group_by: :department)

  Group by department, but by another field

  form
  |> add(:user_id, SelectAssoc, group_by: [:department, :description])

• search_field - schema field to be used in query in search/3. If it’s a nil, then the final value depends on the choice_label value:

  • if :choice_label is nil, :search_field becomes :name
  • if :choice_label is an atom, :search_field gets this atom
  • if :choice_label is a function, :search_field is still nil

• search_query - if the search_field functionality is not enough for you, use this to apply your own query. It’s necessary if you have more than one field to search, e.g. first name and last name.