defmodule Ash.Resource.Transformers.BelongsToAttribute do
@moduledoc """
Creates the attribute for belongs_to relationships that have `define_attribute?: true`
"""
use Spark.Dsl.Transformer
alias Spark.Dsl.Transformer
alias Spark.Error.DslError
@extension Ash.Resource.Dsl
def transform(dsl_state) do
dsl_state
|> Transformer.get_entities([:relationships])
|> Enum.filter(&(&1.type == :belongs_to && &1.define_attribute?))
|> Enum.reject(fn relationship ->
dsl_state
|> Transformer.get_entities([:attributes])
|> Enum.find(&(Map.get(&1, :name) == relationship.source_attribute))
end)
|> Enum.reduce_while({:ok, dsl_state}, fn relationship, {:ok, dsl_state} ->
entity =
Transformer.build_entity(@extension, [:attributes], :attribute,
name: relationship.source_attribute,
type: relationship.attribute_type || :uuid,
allow_nil?:
if relationship.primary_key? do
false
else
relationship.allow_nil?
end,
writable?: relationship.attribute_writable?,
private?: !relationship.attribute_writable?,
primary_key?: relationship.primary_key?
)
valid_opts? = not (relationship.primary_key? && relationship.allow_nil?)
entity_or_error =
if valid_opts? do
entity
else
{:error,
"Relationship cannot be a primary key unless it is also marked as `allow_nil? false`"}
end
add_entity(entity_or_error, dsl_state, relationship)
end)
end
defp add_entity({:ok, attribute}, dsl_state, _relationship),
do: {:cont, {:ok, Transformer.add_entity(dsl_state, [:attributes], attribute, type: :append)}}
defp add_entity({:error, error}, _dsl_state, relationship),
do:
{:halt,
{:error,
DslError.exception(
message:
"Could not create attribute for belongs_to #{relationship.name}: #{inspect(error)}",
path: [:relationships, relationship.name]
)}}
def after?(Ash.Resource.Transformers.BelongsToSourceField), do: true
def after?(_), do: false
end