CODEWITHSUNDEEP
ruby-on-railsrails-activerecord
Kyle
Kyle

Reputation: 4376

Hash getter and setter on ActiveRecord object

I have an ActiveRecord object that was serializing a hash property to one of my database columns. I'd like to get away from this since querying by one of the hash keys is very difficult/not clean. So I've split all the keys of the hash up into separate properties on the model. However, I have a lot of places using this code so in the meantime while I convert everything I'd like to have a property on my ActiveRecord object that is for Rails only (i.e. it doesn't populate back to my database) that wraps up those properties into a hash like it used to be and allows values to be set and get.

So for instance, this is what I used to have:

class MyCls < ActiveRecord::Base
    serialize :state, Hash
    attr_accessible :id, :mode

I'm getting rid of :state and replace it with 7 different values that made up this hash. But I'd still like to be able to access those values like this: MyObj.state[:obj_num]. Even though I now have obj_num as a property (i.e. MyObj.obj_num). I'm thinking the best way to do this would be to have a state property with a getter and a setter, but I can't quite seem to get the syntax right. For the setter I'd need to support both setting the hash as a whole and setting individual keys.

Upvotes: 0

Views: 965

Answers (1)

davidb
davidb

Reputation: 8954

First to say: I dont think thats the best solution. When you touch this code again in lets say 3 years it will be like "WHAAAAAT HAVE I DONE?"... It whould the best solution to replace all the snippets in your code with other code.

You can prepend the method_missing method of the object after removing this line serialize :state to fetch all calls that want to access the not anymore existing serialized field of the object. Its explained here:

http://blog.enriquez.me/2010/2/21/dont-forget-about-respond-to-when-implementing-method-missing/

Its called metaprogramming. Thats the "rails magic" that makes all the find_by_attribute_name stuff working without defining each of these methods. Can be cool stuff but you need to be very carefull and you need to know what your doing.

Upvotes: 1

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