Rails Migration changing column to use Postgres arrays

Question

I am trying to change a column in my database so that it can use the Postgres array data type. Currently the table column is of type string.

I am using the following

Answer 1

Using Rails 4.2 on postgresql 9.4 I was looking to do this and preserve my pre-existing string data as the first element in one element arrays.

It turns out that postgresql cannot coerce a string into a text array without a USING expression to tell it how.

After much fiddling with delicate postgres syntax, I found a good middle way with active record:

def change
  change_column :users, :event_location, :text, array: true, default: [], using: "(string_to_array(event_location, ','))"
end

The only direct postgresql there is the (string_to_array() ) function call. Here are the docs on that--note that you have to supply a delimiter.