Problem: We wanted to add custom validation message, and call the same mysql table column with different names depending on the value of some other field. After much googling I couldn’t find any suitable answers. Posting the solution I came up with, so that it can be of help to others:

Solution: 

I couldn’t find solutions using procs, interpolations, etc. I wrote a custom validator, as all the columns are available there. Below is the sample code:

Please note that linktype and url are columns in the links table.

Also answered a related question on Stackoverflow here:

http://stackoverflow.com/questions/5085284/how-can-i-interpolate-ivars-into-rails-i18n-strings-during-validation/13881719#13881719