A field for handling a has_many (through) relation.

This field is not orderable or searchable.

Field-specific options

See Backpex.Field for general field options.

• :display_field (atom/0) - Required. The field of the relation to be used for displaying options in the select.

• :live_resource (atom/0) - Required. The corresponding live resource of the association. Used to display the title of the modal and generate defaults for :child_fields fields.

• :sort_by (list of atom/0) - A list of columns by which the child element output will be sorted. The sorting takes place in ascending order.

• :child_fields (keyword/0) - WIP

• :pivot_fields (keyword/0) - List to map additional data of the pivot table to Backpex fields.

• :options_query (function of arity 2) - Manipulates the list of available options in the select. Can be used to select additional data for the display_field option or to limit the available entries.",

  Defaults to fn (query, _field) -> query end which returns all entries.

Example

@impl Backpex.LiveResource
def fields do
[
  addresses: %{
    module: Backpex.Fields.HasManyThrough,
    label: "Addresses",
    display_field: :street,
    live_resource: DemoWeb.AddressLive,
    sort_by: [:zip, :city],
    pivot_fields: [
      type: %{
        module: Backpex.Fields.Select,
        label: "Address Type",
        options: [Shipping: "shipping", Billing: "billing"]
      }
    ]
  }
]
end

The field requires a Ecto.Schema.has_many/3 relation with a mandatory through option in the main schema. Any extra column in the pivot table besides the relational id's must be mapped in the pivot_fields option or given a default value.