I already google'd aroung a little bit and seems there's no satisfying answer for my problem.
I have a table with column of type string.
I'd like to run following migration:
class ChangeColumnToBoolean < ActiveRecord::Migration
def up
change_column :users, :smoking, :boolean
end
end
When I run this I get following error
PG::Error: ERROR: column "smoking" cannot be cast automatically to type boolean
HINT: Specify a USING expression to perform the conversion.
: ALTER TABLE "users" ALTER COLUMN "smoking" TYPE boolean
I know I can perform this migration using pure SQL but still it would be nicer if I could do it with Rails. I went through Rails code and seems theres no such possibility, but maybe someone knows a way?
I'm not interested in:
– pure SQL
– dropping the column
– creating another column, converting data, dropping original and then renaming
Best Answer
If your strings in
smoking
column are already valid boolean values, the following statement will change the column type without losing data:Similarly, you can use this statement to cast columns to integer:
I am using Postgres. Not sure whether this solution works for other databases.