Question

My state model looks like this:

class State < ActiveRecord::Base   belongs_to :country   named_scope :order_by_name, :order => :name    validates_presence_of [:country, :name]    def <=>(other)     name <=> other.name   end  end 

My country model looks like this:

class Country < ActiveRecord::Base   has_many :states   named_scope :order_by_name, :order => :name      def <=>(other)     name <=> other.name   end end 

This works in a SQLite environment:

>> Country.find_by_iso('US').states => [#<State id: 1, name: 'Alaska', abbr: 'AK',  #  ..... 

But in a postgresql environment, I get this:

>> Country.find_by_iso('US').states ActiveRecord::StatementInvalid: PGError: ERROR:  operator does not exist: character varying = integer LINE 1: SELECT * FROM 'states' WHERE ('states'.country_id = 214)                                                            ^ HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts. : SELECT * FROM 'states' WHERE ('states'.country_id = 214)  

Any thoughts?

Answer 1

The error message is quite clear, you’re trying to do a comparison between different types, hence the ‘character varying = integer’ notice.

The solution: make country_id a column of type ‘int’ instead of ‘varchar’.