Re: [Rails] Re: How to set new object fields with not-hash object in ActiveRecord?

Fred, thanks for your reply.

On Sat, Apr 30, 2011 at 12:29 AM, Frederick Cheung
<frederick.cheung@gmail.com> wrote:
>
>
> On Apr 29, 11:16 am, Haruka YAGNI <hya...@gmail.com> wrote:
>> Hi, everyone.
>> I am using Geokit and Geokit-Rails3 on Ruby on Rails 3.0.3 / Ruby
>> 1.8.7.
>>
>> My model Location (which acts_as_mappable) is often created with lat
>> and lng.
>>
>> For avoiding repeating yourself, I tried to override initialize method
>> and try to use Geokit::LatLng.normalize (this method creates a LatLng
>> object from string/array/etc..), but the following codes does not
>> work, and show curious errors.
>>
>> There are also tests using the original style (:lat=>..., :lng=>...)
>> and they works fine.
>> According to "p ll" in location.rb, ll is correct.
>>
>> Thanks in advance.
>>
>> -- location.rb
>> class Location < ActiveRecord::Base
>>   acts_as_mappable :default_units=>:kms, :default_formula=>:flat
>>   attr_accessible :lat, :lng
>>
>>   def initialize(args)
>>     begin
>>       ll = Geokit::LatLng.normalize(args)
>>       p ll
>>       lat = ll.lat; lng = ll.lng
>>     rescue
>>       super
>>     end
> This doesn't actually set your attributes, it just creates 2 local
> variables.
> Moreover, you're not (unless an exception is thrown) calling super, so
> active record's internal state isn't setup correctly - somethig like
> super(:lat => ll.lat, :lng => ll.lng) is probably alright.

Thanks, it passes the test.
super(in rescue) is called when the parameter is a normal hash, because
Geokit::LatLng.normalize throws an exception when it cannot make
LatLng object from the argument, and LatLng does not support a hash.

> You probably also want to be careful of the case where the object is
> being loaded from the database

Some sites warns that AR does not call initialize method on loading a object
from DB. I just use my custom initialization on newly creating a object from
a form input.

As long as I tested (just make a new object and load it), this method works
without problem.
Is there possibility of some bugs? How can I test it?

>
> Fred
>
>
>>   end
>> end
>>
>> -- a part of location_spec.rb
>>     it "should make new Location from LatLng object" do
>>       Location.create!(Geokit::LatLng.normalize("35,135")).lat.should
>> == 35
>>     end
>>
>>     it "should make new Location from String" do
>>       Location.create!("35, 150").lat.should == 35
>>     end
>>
>>     it "should make new Location from Array" do
>>       p Location.new([35,150])#.lat.should == 35
>>     end
>>
>> -- errors (shortly)
>>   NoMethodError: ... while evaluationg nil.[]
>>   NoMethodError: undefined method `has_key?' for nil:NilClass  (in `p')
>
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--
Haruka YAGNI
hyagni@gmail.com

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