diff --git a/app/models/metadata_belongs_to.rb b/app/models/metadata_belongs_to.rb
index e1b84438..8726f1b1 100644
--- a/app/models/metadata_belongs_to.rb
+++ b/app/models/metadata_belongs_to.rb
@@ -41,7 +41,7 @@ class MetadataBelongsTo < MetadataRelatedPosts
     # anterior
     if belonged_to.present?
       if belonged_to[inverse].respond_to? :has_one
-        belonged_to[inverse].value = nil
+        belonged_to[inverse].value = ''
       else
         belonged_to[inverse].value = belonged_to[inverse].value.reject do |rej|
           rej == post.uuid.value
diff --git a/app/models/metadata_has_one.rb b/app/models/metadata_has_one.rb
index 38911e1d..d1705e7d 100644
--- a/app/models/metadata_has_one.rb
+++ b/app/models/metadata_has_one.rb
@@ -1,29 +1,24 @@
 # 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
+class MetadataHasOne < MetadataBelongsTo
+  alias has_one belongs_to
+  alias had_one belonged_to
 
   def save
-    super
+    # XXX: DRY
+    if !changed?
+      self[:value] = document_value
+
+      return true
+    end
+
+    self[:value] = sanitize value
 
     return true unless changed?
     return true unless inverse?
 
-    had_one&.value = nil
-    has_one&.value = post.uuid.value
+    had_one[inverse]&.value = '' if had_one
+    has_one[inverse]&.value = post.uuid.value if has_one
 
     true
   end