change_column_null(table_name, column_name, null, default = nil)
Instance Public methods
Sets or removes a +NOT NULL+ constraint on a column. The null
flag indicates whether the value can be NULL. For example
change_column_null(:users, :nickname, false)
says nicknames cannot be NULL (adds the constraint), whereas
change_column_null(:users, :nickname, true)
allows them to be NULL (drops the constraint).
The method accepts an optional fourth argument to replace existing +NULL+s with some other value. Use that one when enabling the constraint if needed, since otherwise those rows would not be valid.
Please note the fourth argument does not set a column's default.
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