feat: Support Many To Many Association (#9)

* feat: Support Many To Many Association

* feat: put nil outside the association type

lib/typed_ecto_schema/ecto_type_mapper.ex

@@ -1,14 +1,13 @@
 defmodule TypedEctoSchema.EctoTypeMapper do
   @moduledoc false
 
-  alias Ecto.Association.NotLoaded
-
-  @schema_many_function_name [:embeds_many, :has_many]
+  @schema_many_function_name [:embeds_many, :has_many, :many_to_many]
 
   @schema_assoc_function_name [
     :has_many,
     :has_one,
-    :belongs_to
+    :belongs_to,
+    :many_to_many
   ]
 
   @module_for_ecto_type %{
@@ -42,8 +41,8 @@ defmodule TypedEctoSchema.EctoTypeMapper do
   def type_for(ecto_type, function_name, nullable_default, opts) do
     ecto_type
     |> base_type_for(opts)
-    |> wrap_in_list_if_many(function_name)
-    |> add_not_loaded_if_assoc(function_name)
+    |> wrap_embeds_many(function_name)
+    |> wrap_assoc_type(function_name)
     |> add_nil_if_nullable(field_is_nullable?(nullable_default, function_name, opts))
   end
 
@@ -137,23 +136,26 @@ defmodule TypedEctoSchema.EctoTypeMapper do
       any()
     end
   end
-  @spec wrap_in_list_if_many(Macro.t(), function_name()) :: Macro.t()
-  defp wrap_in_list_if_many(type, function_name)
-       when function_name in @schema_many_function_name do
+
+  @spec wrap_assoc_type(Macro.t(), function_name()) :: Macro.t()
+  defp wrap_assoc_type(type, function_name) when function_name in @schema_assoc_function_name do
     quote do
-      list(unquote(type))
+      unquote(Ecto.Schema).unquote(function_name)(unquote(type))
     end
   end
 
-  defp wrap_in_list_if_many(type, _), do: type
+  defp wrap_assoc_type(type, _function_name) do
+    type
+  end
 
-  @spec add_not_loaded_if_assoc(Macro.t(), function_name()) :: Macro.t()
-  defp add_not_loaded_if_assoc(type, function_name)
-       when function_name in @schema_assoc_function_name do
-    quote(do: unquote(type) | unquote(NotLoaded).t())
+  @spec wrap_embeds_many(Macro.t(), function_name()) :: Macro.t()
+  defp wrap_embeds_many(type, :embeds_many) do
+    quote do
+      list(unquote(type))
+    end
   end
 
-  defp add_not_loaded_if_assoc(type, _), do: type
+  defp wrap_embeds_many(type, _), do: type
 
   @spec add_nil_if_nullable(Macro.t(), nullable :: boolean) :: Macro.t()
   defp add_nil_if_nullable(type, false), do: type

lib/typed_ecto_schema/syntax_sugar.ex

@@ -13,7 +13,8 @@ defmodule TypedEctoSchema.SyntaxSugar do
     :embeds_many,
     :has_one,
     :has_many,
-    :belongs_to
+    :belongs_to,
+    :many_to_many
   ]
 
   @embeds_function_names [:embeds_one, :embeds_many]

lib/typed_ecto_schema/type_builder.ex

@@ -10,6 +10,7 @@ defmodule TypedEctoSchema.TypeBuilder do
           | :has_one
           | :has_many
           | :belongs_to
+          | :many_to_many
 
   @typep schema_option ::
            {:null, boolean()}

test/typed_ecto_schema_test.exs

@@ -37,6 +37,14 @@ defmodule TypedEctoSchemaTest do
     end
   end
 
+  defmodule ManyToMany do
+    use TypedEctoSchema
+
+    typed_schema "many_to_many" do
+      field(:int, :integer)
+    end
+  end
+
   {:module, _name, bytecode, _exports} =
     defmodule TestStruct do
       use TypedEctoSchema
@@ -57,6 +65,7 @@ defmodule TypedEctoSchemaTest do
         has_one(:has_one, HasOne)
         has_many(:has_many, HasMany)
         belongs_to(:belongs_to, BelongsTo)
+        many_to_many(:many_to_many, ManyToMany, join_through: "join_table")
         timestamps()
       end
 
@@ -218,6 +227,7 @@ defmodule TypedEctoSchemaTest do
           has_one(:has_one, HasOne)
           has_many(:has_many, HasMany)
           belongs_to(:belongs_to, BelongsTo)
+          many_to_many(:many_to_many, ManyToMany, join_through: "join_table")
           timestamps()
         end
 
@@ -236,12 +246,11 @@ defmodule TypedEctoSchemaTest do
                 enum_type_required: :foo1 | :foo2 | :foo3,
                 embed: Embedded.t() | nil,
                 embeds: list(Embedded.t()),
-                has_one: (HasOne.t() | unquote(NotLoaded).t()) | nil,
-                has_many: list(HasMany.t()) | unquote(NotLoaded).t(),
-                belongs_to:
-                  (BelongsTo.t() | unquote(NotLoaded).t())
-                  | nil,
+                has_one: unquote(Ecto.Schema).has_one(unquote(HasOne).t()) | nil,
+                has_many: unquote(Ecto.Schema).has_many(unquote(HasMany).t()),
+                belongs_to: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
                 belongs_to_id: integer() | nil,
+                many_to_many: unquote(Ecto.Schema).many_to_many(unquote(ManyToMany).t()),
                 inserted_at: unquote(NaiveDateTime).t() | nil,
                 updated_at: unquote(NaiveDateTime).t() | nil
               }
@@ -303,14 +312,11 @@ defmodule TypedEctoSchemaTest do
           enum_type_required: :foo1 | :foo2 | :foo3,
           embed: unquote(Embedded).t() | nil,
           embeds: list(unquote(Embedded).t()),
-          has_one:
-            (unquote(HasOne).t() | unquote(NotLoaded).t())
-            | nil,
-          has_many: list(unquote(HasMany).t()) | unquote(NotLoaded).t(),
-          belongs_to:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil,
+          has_one: unquote(Ecto.Schema).has_one(unquote(HasOne).t()) | nil,
+          has_many: unquote(Ecto.Schema).has_many(unquote(HasMany).t()),
+          belongs_to: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
           belongs_to_id: integer() | nil,
+          many_to_many: unquote(Ecto.Schema).many_to_many(unquote(ManyToMany).t()),
           inserted_at: unquote(NaiveDateTime).t() | nil,
           updated_at: unquote(NaiveDateTime).t() | nil
         ]
@@ -329,12 +335,8 @@ defmodule TypedEctoSchemaTest do
           normal: integer(),
           enforced: integer(),
           overriden: integer() | nil,
-          has_one:
-            (unquote(HasOne).t() | unquote(NotLoaded).t())
-            | nil,
-          belongs_to:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil,
+          has_one: unquote(Ecto.Schema).has_one(unquote(HasOne).t()) | nil,
+          belongs_to: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
           belongs_to_id: integer()
         ]
       end
@@ -348,21 +350,13 @@ defmodule TypedEctoSchemaTest do
       quote do
         [
           __meta__: unquote(Metadata).t(),
-          normal:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil,
+          normal: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
           normal_id: integer() | nil,
-          with_custom_fk:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil,
+          with_custom_fk: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
           custom_fk: integer() | nil,
-          custom_type:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil,
+          custom_type: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil,
           custom_type_id: binary() | nil,
-          no_define:
-            (unquote(BelongsTo).t() | unquote(NotLoaded).t())
-            | nil
+          no_define: unquote(Ecto.Schema).belongs_to(unquote(BelongsTo).t()) | nil
         ]
       end