Question

We have script/generate migration add_fieldname_to_tablename fieldname:datatype syntax for adding new columns to a model.

On the same line, do we have a script/generate for changing the datatype of a column? Or should I write SQL directly into my vanilla migration?

I want to change a column from datetime to date.

Answer 1

Use #change_column.

change_column(:table_name, :column_name, :date)

# a few more examples:
change_column(:suppliers, :name, :string, limit: 80)
change_column(:accounts, :description, :text)

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NOTE: the same result can be achieved even outside of db migrations, this might be handy for testing/debugging but this method needs to be used very cautiously:

ActiveRecord::Base.connection.change_column(:table_name, :column_name, :date)