Active Record 4.x and MySQL table column type without using migrations - mysql

Question

I'm doing some test with Sinatra v1.4.4 and Active Record v4.0.2. I've created a DBase and a table named Company with Mysql Workbench. In table Company there are two fields lat & long of DECIMAL(10,8) and DECIMAL(11,8) type respectively. Without using migrations I defined the Company model as follow:
class Company < ActiveRecord::Base
end
Everything works except the fact that lat and lng are served as string and not as float/decimal. Is there any way to define the type in the above Class Company definition. Here you can find the Sinatra route serving the JSON response:
get '/companies/:companyId' do |companyId|
begin
gotCompany = Company.find(companyId)
[200, {'Content-Type' => 'application/json'}, [{code:200, company: gotCompany.attributes, message: t.company.found}.to_json]]
rescue
[404, {'Content-Type' => 'application/json'}, [{code:404, message:t.company.not_found}.to_json]]
end
end
Active Record correctly recognize them as decimal. For example, executing this code:
Company.columns.each {|c| puts c.type}
Maybe its the Active Record object attributes method typecast?
Thanks,
Luca

Answer 1

You can wrap the getter methods for those attributes and cast them:
class Company < ActiveRecord::Base
def lat
read_attribute(:lat).to_f
end
def lng
read_attribute(:lng).to_f
end
end
That will convert them to floats, e.g:
"1.61803399".to_f
=> 1.61803399
Edit:
Want a more declarative way? Just extend ActiveRecord::Base:
# config/initializers/ar_type_casting.rb
class ActiveRecord::Base
def self.cast_attribute(attribute, type_cast)
define_method attribute do
val = read_attribute(attribute)
val.respond_to?(type_cast) ? val.send(type_cast) : val
end
end
end
Then use it like this:
class Company < ActiveRecord::Base
cast_attribute :lat, :to_f
cast_attribute :lng, :to_f
end
Now when you call those methods on an instance they will be type casted to_f.

Answer 2

Following diego.greyrobot reply I modified my Company class with an additional method. It overrides the attributes method and afterwards typecast the needed fields. Yet something more declarative would be desirable imho.
class Company < ActiveRecord::Base
def attributes
retHash = super
retHash['lat'] = self.lat.to_f
retHash['lng'] = self.lng.to_f
retHash
end
end