How do I add a default value to columns in an existing table?

Question

Possible Duplicate:
Add a default value to a column through a migration

I know it wouldn't affect existing data, but for every record going forward, I would like for there to be a default value - i.e. not null to be stored in the column.

How do I do that for existing columns without having to drop the columns?

see http://stackoverflow.com/questions/7098602/add-a-default-value-to-a-column-through-a-migration — jstim, Oct 11 '12 at 23:53
http://stackoverflow.com/questions/8627156/adding-default-true-to-boolean-in-existing-rails-column/8627171#8627171 — Robin, Oct 11 '12 at 23:54

score 1 · Answer 1 · answered Oct 12 '12 at 00:18

1

Following the links in the comments, this works for me:

change_table :my_model do |t|
     t.change_default :my_column, 0
end

Where 0 is the default value I wanted to set - and :my_column is the name of the column.

Additional Info can be found in the API Docs

answered Oct 12 '12 at 00:18

marcamillion

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Keep in mind that on MySQL this will change existing NULL values to the new default, but not on Postgres. – Max Dunn Oct 12 '12 at 01:21
Interesting. Will keep that in mind. – marcamillion Oct 12 '12 at 01:21

How do I add a default value to columns in an existing table?

1 Answers1