diff --git a/server.rb b/server.rb
index accc13c..54cf8ab 100755
--- a/server.rb
+++ b/server.rb
@@ -250,20 +250,23 @@ def add_part(part)
   # update family
   family = nil
   field = "family"
-  part[field] = nil if part[field] and 0 == part[field].length
   if part[field] then
-    statement = @db.prepare("SELECT id FROM part WHERE name = ?")
-    family = statement.execute(part[field]).to_a
-    raise StandardError.new("family not existing") if family.empty?
-    update = @db.prepare("UPDATE part SET #{field} = ? WHERE id = ?")
-    update.execute(family[0]["id"], part["id"])
-    family = get_part_by_id(family[0]["id"])
+    if part[field].empty? then
+      update = @db.prepare("UPDATE part SET #{field} = NULL WHERE id = ?")
+      update.execute(part["id"])
+    else
+      statement = @db.prepare("SELECT id FROM part WHERE name = ?")
+      family = statement.execute(part[field]).to_a
+      raise StandardError.new("family not existing") if family.empty?
+      update = @db.prepare("UPDATE part SET #{field} = ? WHERE id = ?")
+      update.execute(family[0]["id"], part["id"])
+      family = get_part_by_id(family[0]["id"])
+    end
   end
   # update fields
   fields_txt = ["name", "description", "details", "mpn", "package", "datasheet", "page"];
   fields_txt.each do |field|
     next unless part[field]
-    part[field] = nil if part[field].kind_of?(String) and 0 == part[field].length
     next if family and family[field] == part[field]
     update = @db.prepare("UPDATE part SET #{field} = ? WHERE id = ?")
     update.execute(part[field], part["id"])
@@ -271,7 +274,6 @@ def add_part(part)
   # update manufacturer and package
   field_ref = ["manufacturer"]
   field_ref.each do |field|
-    part[field] = nil if part[field] and 0 == part[field].length
     next if family and family[field] == part[field]
     if part[field] then
       statement = @db.prepare("SELECT id FROM #{field} WHERE LOWER(name) = ?")