Rails gem - geoipcity is not being included in the application

I installed the geoip_city gem, and i tested the gem in irb... Now when I am using the gem in the application I get an error

unini开发者_JS百科tialized constant ApplicationController::GeoIPCity

I guessed it is because I did not add the line

require geoip_city

So I tried adding the line to the function I used the code in, but then I got the error

No such file -- geoip_city

Please help.

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Have your require rubygems before ?

require 'rubygems'
require 'geoip_city'