Rails 3.1. Heroku PGError: operator does not exist: character varying = integer

Your problem is here:

WHERE "reviews"."trip_id" = 32

and the error message says that:

operator does not exist: character varying = integer

so you have created your trip_id column in reviews as a string rather than as an integer. That will work fine in SQLite because SQLite's type system is rather loose but it won't work in PostgreSQL as PostgreSQL is quite a bit stricter.

You could try adding a migration to fix the type of trip_id:

def change  change_column :reviews, :trip_id, :integerend

and if that doesn't work then drop and recreate the table:

def change  drop_table :reviews  create_table :reviews do |t|    #...    t.integer :trip_id    #...  endend

You could also do an ALTER TABLE through raw SQL if you have data that you want to preserve and the change_column doesn't work:

def change  execute %q{    alter table reviews    alter column trip_id    type int using cast(trip_id as int)  }end

That should work in PostgreSQL (but not SQLite) as long as you don't have any broken data in your trip_id.

Once you have that sorted out, you should install PostgreSQL and switch your development environment to that. Developing on top of SQLite and deploying to PostgreSQL (or developing on top of one database and deploying on top of any other database for that matter) is a bad idea and will cause you all sorts of grief and confusion.

You could leave the column as a text/varchar data type, and cast it as an integer...

WHERE "reviews"."trip_id"::int = 32

A simpler way to do the migration is this:

change_column :reviews, :trip_id, 'integer USING CAST(trip_id AS integer)'