Json text to text array migration questions

Rails
1

Hi,

I have field in postgres (9.2.4) with type json. The field looks like

   Column        |            Type             | Modifiers | Storage

|
Stats target | Description
---------------------±----------------------------±----------±---------±-------------±------------
my_id_field | json | |
extended
| |

When I do " select my_id_field::json from table1", it returns something
like

[]
[]
[]
[“abc”]
[]
[]
[]

I like to change this from type json to text[] and included the
following
in the migration

execute “alter table table1 add column new_id_field text[] default
‘{}’::text[]”
execute “UPDATE table1 SET new_id_field = [my_id_field] where
my_id_field
is not null”

I ended up with data like [[“abc”]] and [[]], which was not what I
wanted

Questions:

  1. how do I convert the json type to text[]?
  2. in ActiveRecord, how do I select rows from table1 that are not []?

TIA
m