Rails Migration to make a column null => true

问题:

I had originally created a table with column as

t.string   "email",  :default => "", :null => false 

The requirement has changed and now I need to allow email to be null. How can I write a migration to make :null => true

回答1:

Try:

change_column :table_name, :email, :string, :null => true 

回答2:

I could not get the above solution to work with Active Record 4.0.8 and Postgresql 9.3

However change_column_null worked perfectly.

change_column_null :users, :email, true 

The reverse has a nice option to update existing records (but not set the default) when null is not allowed.

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