Internal server error when creating object with an already existing name

[ChristinaSi]

When creating an article, a recipe, a quantity, a shop section, a purchase list, a meal on the same day or a tag with a name that already exists the message "Internal server error" appears. Check the name when submitting object, show good error message and stay on the same site with the forms still filled.

[dboehmer]

I started to do this for quantities, purchase lists, shop sections but with our current setup it's a tedious task:-(

I think we should solve this by adopting a framework for input validation (a Perl module for the server side part). I'm will do some research on this later and come back to this issue …