Model Associations

Rails
1

Hi,

I have just started using rails and i am trying to use IP database to
get user location.

Here are the database schemas…

[code]CREATE TABLE IF NOT EXISTS ip_group_cities (
ip_start bigint(20) NOT NULL,
location int(11) NOT NULL,
UNIQUE KEY index_ip_group_cities_on_ip_start (ip_start)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS iso3166_countries (
code varchar(2) NOT NULL,
name varchar(64) NOT NULL,
UNIQUE KEY index_iso3166_countries_on_code (code)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS locations (
id int(11) NOT NULL AUTO_INCREMENT,
country_code varchar(2) NOT NULL,
region_code varchar(2) NOT NULL,
city varchar(64) NOT NULL,
zipcode varchar(8) NOT NULL,
latitude float NOT NULL,
longitude float NOT NULL,
metrocode varchar(3) NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;[/code]

and here is the sql SELECT locations.city,locations.id FROM ip_group_cities,locations where ip_group_cities.ip_start <= INET_ATON('$ip') AND ip_group_cities.location = locations.id order by ip_group_cities.ip_start desc limit 1

i have used these associaltions

class Iso3166Country < ActiveRecord::Base has_many :locations, :foreign_key: :id end

class IpGroupCity < ActiveRecord::Base has_one :locations, :foreign_key => :id end

class Location < ActiveRecord::Base has_many :ip_group_cities, :foreign_key => :location belongs_to :iso3166_countries, :foreign_key => :country_code end

But when i run this code

C = Location.find(1);

It does not show me the columns from the other tables… I mean i dont
see a name column from the Iso3166Countries table.

What am i doing wrong?

2 
C = Location.find(1);

It does not show me the columns from the other tables… I mean i dont
see a name column from the Iso3166Countries table.

All you are asking rails to do is load a location object - what were you
expecting it to do?

Fred

3

On 20 July 2010 20:27, Amit K. [email protected] wrote:

UNIQUE KEY index_ip_group_cities_on_ip_start (ip_start)
id int(11) NOT NULL AUTO_INCREMENT,
and here is the sql SELECT locations.city,locations.id FROM ip_group_cities,locations where ip_group_cities.ip_start <= INET_ATON('$ip') AND ip_group_cities.location = locations.id order by ip_group_cities.ip_start desc limit 1

i have used these associaltions

[code]class Iso3166Country < ActiveRecord::Base
has_many :locations, :foreign_key: :id

What is the foreign_key spec here supposed to be doing?

end
[/code]

[code]class IpGroupCity < ActiveRecord::Base
has_one :locations, :foreign_key => :id

If you really mean has_one then it should be :location (singular). I
suspect you mean belongs_to however since you have location has_many
IpGroupCities below. Again what is the foreign_key spec for?

end
[/code]

[code]class Location < ActiveRecord::Base
has_many :ip_group_cities, :foreign_key => :location

Again I do not understand the foreign key spec

belongs_to :iso3166_countries, :foreign_key => :country_code
end
[/code]

But when i run this code

[code]
C = Location.find(1);

You would be better to use lower case C.

[/code]

It does not show me the columns from the other tables… I mean i dont
see a name column from the Iso3166Countries table.

Try C.iso3166_country. It will not fetch the association data until
you ask.

Colin