Validate URL alias before saving Node

Question

I have a custom content type which has a url alias pattern of [node:type]/[node:title].

How can I validate the node form in order to prevent the url alias from becoming [node:type]/[node:title]-0 in case the same title is used somewhere else.

Basically, I would like to prevent the node from saving, and display an error message if the url alias will end up having a "-0" at the end.

Answer 1

How about using the Unique field module for this? Here is a quote about the module's project page:

This module performs additional validation when a node is created or updated by a user to require that a node's title, author, language, and CCK fields are unique within a given context.