activerecord - Rails Migration Prepend Column? -

i'm trying figure out how run migration prepends string beginning of column. in specific case have column called url stores after domain (e.g. /test.html). want prepend single string http://google.com beginning of url. in case of example, resulting string value of url entry http://google.com/test.html.

how can accomplish migration?

i'm not sure qualifies should put migration; generally, migrations change structure of database, rather change format of data inside of it.

the easiest , quickest way not futz around in database @ all, , instead make url method of model return "http://google.com#{read_attribute(:url)}". if want change data in database, i'd make rake task it, like:

namespace :data   task :add_domain     model.each |model|       model.url = "http://google.com#{model.url}" if model.url !~ /google\.com/       model.save if model.changed?     end   end end 

if must migration you, migration's up similar internals of rake task. (or call rake task directly.)