fix: add back in writable? option to relationships, and add attribute_writable? to belongs_to

.formatter.exs

@@ -18,6 +18,7 @@ locals_without_parens = [
   attribute: 1,
   attribute: 2,
   attribute: 3,
+  attribute_writable?: 1,
   authorize_if: 1,
   authorize_if: 2,
   authorize_unless: 1,

lib/ash/changeset/changeset.ex

@@ -1796,6 +1796,15 @@ defmodule Ash.Changeset do
 
         add_error(changeset, error)
 
+      %{writable?: false} = relationship ->
+        error =
+          InvalidRelationship.exception(
+            relationship: relationship.name,
+            message: "Relationship is not editable"
+          )
+
+        add_error(changeset, error)
+
       %{manual: manual} = relationship when not is_nil(manual) ->
         error =
           InvalidRelationship.exception(

lib/ash/resource/relationships/belongs_to.ex

@@ -21,6 +21,7 @@ defmodule Ash.Resource.Relationships.BelongsTo do
     :writable?,
     :context,
     :description,
+    :attribute_writable?,
     validate_destination_field?: true,
     cardinality: :one,
     type: :belongs_to
@@ -39,6 +40,8 @@ defmodule Ash.Resource.Relationships.BelongsTo do
           primary_key?: boolean,
           define_field?: boolean,
           field_type: term,
+          writable?: boolean,
+          attribute_writable?: boolean,
           destination_field: atom,
           private?: boolean,
           source_field: atom | nil,
@@ -56,12 +59,6 @@ defmodule Ash.Resource.Relationships.BelongsTo do
 
   @opt_schema Ash.OptionsHelpers.merge_schemas(
                 [
-                  writable?: [
-                    type: :boolean,
-                    doc:
-                      "Whether or not the attribute created by this relationship will be marked with `writable?: true`.",
-                    default: false
-                  ],
                   primary_key?: [
                     type: :boolean,
                     default: false,
@@ -73,6 +70,15 @@ defmodule Ash.Resource.Relationships.BelongsTo do
                     doc:
                       "Whether this relationship must always be present, e.g: must be included on creation, and never removed (it can still be changed)"
                   ],
+                  attribute_writable?: [
+                    type: :boolean,
+                    default: false,
+                    doc: """
+                    Whether this relationship's generated attribute will be marked as writable.
+
+                    Has no effect when combined with `define_field?: false`.
+                    """
+                  ],
                   define_field?: [
                     type: :boolean,
                     default: true,

lib/ash/resource/relationships/has_many.ex

@@ -16,6 +16,7 @@ defmodule Ash.Resource.Relationships.HasMany do
     :violation_message,
     :manual,
     :api,
+    :writable?,
     no_fields?: false,
     could_be_related_at_creation?: false,
     validate_destination_field?: true,
@@ -32,6 +33,7 @@ defmodule Ash.Resource.Relationships.HasMany do
           no_fields?: boolean,
           name: atom,
           type: Ash.Type.t(),
+          writable?: boolean,
           destination: Ash.Resource.t(),
           destination_field: atom,
           private?: boolean,

lib/ash/resource/relationships/has_one.ex

@@ -18,6 +18,7 @@ defmodule Ash.Resource.Relationships.HasOne do
     :not_found_message,
     :violation_message,
     :manual,
+    :writable?,
     no_fields?: false,
     could_be_related_at_creation?: false,
     validate_destination_field?: true,
@@ -33,6 +34,7 @@ defmodule Ash.Resource.Relationships.HasOne do
           name: atom,
           read_action: atom,
           no_fields?: boolean,
+          writable?: boolean,
           type: Ash.Type.t(),
           filter: Ash.Filter.t() | nil,
           destination: Ash.Resource.t(),

lib/ash/resource/relationships/many_to_many.ex

@@ -19,6 +19,7 @@ defmodule Ash.Resource.Relationships.ManyToMany do
     :description,
     :context,
     :filter,
+    :has_many,
     could_be_related_at_creation?: false,
     validate_destination_field?: true,
     cardinality: :many,
@@ -29,6 +30,7 @@ defmodule Ash.Resource.Relationships.ManyToMany do
           type: :many_to_many,
           cardinality: :many,
           source: Ash.Resource.t(),
+          has_many: boolean,
           private?: boolean,
           filter: Ash.Filter.t() | nil,
           read_action: atom,

lib/ash/resource/relationships/shared_options.ex

@@ -53,6 +53,13 @@ defmodule Ash.Resource.Relationships.SharedOptions do
       For example, if a value is added that has no match in the destination (very hard to do with the way Ash relationship changes work).
       """
     ],
+    writable?: [
+      type: :boolean,
+      default: true,
+      doc: """
+      Wether or not the relationship may be edited.
+      """
+    ],
     read_action: [
       type: :atom,
       doc: """

lib/ash/resource/transformers/belongs_to_attribute.ex

@@ -29,7 +29,7 @@ defmodule Ash.Resource.Transformers.BelongsToAttribute do
             else
               not relationship.required?
             end,
-          writable?: relationship.writable?,
+          writable?: relationship.attribute_writable?,
           private?: true,
           primary_key?: relationship.primary_key?
         )

test/resource/relationships/belongs_to_test.exs

@@ -56,6 +56,24 @@ defmodule Ash.Test.Resource.Relationships.BelongsToTest do
              ] = Ash.Resource.Info.attributes(Post)
     end
 
+    test "it creates an attribute that honors attribute_writable?" do
+      defposts do
+        relationships do
+          belongs_to(:foobar, FooBar, attribute_writable?: true)
+        end
+      end
+
+      assert [
+               _,
+               %Ash.Resource.Attribute{
+                 name: :foobar_id,
+                 primary_key?: false,
+                 type: Ash.Type.UUID,
+                 writable?: true
+               }
+             ] = Ash.Resource.Info.attributes(Post)
+    end
+
     test "it creates a relationship" do
       defposts do
         relationships do