feat: establecer relaciones bidireccionales

app/models/metadata_belongs_to.rb

@@ -40,13 +40,21 @@ class MetadataBelongsTo < MetadataRelatedPosts
     # Si estamos cambiando la relación, tenemos que eliminar la relación
     # anterior
     if belonged_to.present?
-      belonged_to[inverse].value = belonged_to[inverse].value.reject do |rej|
-        rej == post.uuid.value
+      if belonged_to[inverse].respond_to? :has_one
+        belonged_to[inverse].value = nil
+      else
+        belonged_to[inverse].value = belonged_to[inverse].value.reject do |rej|
+          rej == post.uuid.value
+        end
       end
     end
 
     # No duplicar las relaciones
-    belongs_to[inverse].value = (belongs_to[inverse].value.dup << post.uuid.value) unless belongs_to.blank? || included?
+    if belongs_to[inverse].respond_to? :has_one
+      belongs_to[inverse].value = post.uuid.value
+    else
+      belongs_to[inverse].value = (belongs_to[inverse].value.dup << post.uuid.value) unless belongs_to.blank? || included?
+    end
 
     true
   end

app/models/metadata_has_one.rb

@@ -1,4 +1,34 @@
 # frozen_string_literal: true
 
 class MetadataHasOne < MetadataHasMany
+  def had_one
+    return default_value if value_was.blank?
+
+    posts.find(uuid: value)
+  end
+
+  def has_one
+    return default_value if value.blank?
+
+    posts.find(uuid: value)
+  end
+
+  def had_many; end
+  def has_many; end
+
+  def save
+    super
+
+    return true unless changed?
+    return true unless inverse?
+
+    had_one&.value = nil
+    has_one&.value = post.uuid.value
+
+    true
+  end
+
+  def related_methods
+    @related_methods ||= %i[has_one had_one].freeze
+  end
 end