I've just started learning Ruby on Rails and I was wondering if there is a way by which I can access a variable defined in a model's method. I have a controller where I want to access the variable. I have a model
class abc
def score
sum = 10
end
end
And there is a controller
class FirstController < ApplicationController
def get_score
end
end
So I want to get the value of variable sum in method get_score. How can I achieve this?
This is an object orientated programming question; you're not calling a variable from your model, you're accessing either an attribute or an instance value (very important in terms of scoping etc) from a class.
--
You'll either need to make the variable a class variable, invoke it as an instance method, or have class method to return it:
#app/models/model.rb
class Model < ActiveRecord::Base
cattr_accessor :sum #-> Model.sum class variable (static)
@@sum = 10
def self.sum
10 #-> Model.sum class method (static)
end
end
What you do depends on what type of data you're looking to return.
- If the data is static, use a class method / variable
- If the data is dynamic, use an instance method
Above is the code you'd use if you want to return a static value.
If you wanted to return a dynamic value, you'd use:
#app/models/model.rb
class Model < ActiveRecord::Base
def score
self.games * self.goals # -> @model.sum instance method (dynamic)
end
end
--
The difference is that if you use a class value, it is only available through initialization of the class. IE you can call Model.sum and have access to the record.
Instance methods / values are only accessible through an instance of the class:
@model = Model.find 5 #-> creates a new instance of the class
@model.sum #-> pulls the dynamic sum value of the class instance
In your case, you'd be best using an instance method:
#app/models/abc.rb
class Abc < ActiveRecord::Base
def score
10
end
end
#app/controllers/first_controller.rb
class FirstController < ApplicationController
def get_score
@abc = Abc.new
@abc.sum #-> 10
end
end
This way, your data will be dynamic, allowing you to manipulate it etc.
In ruby method returns the last statement value if return statement is not return explicitly. You can access the score as follows:
class FirstController < ApplicationController
def get_score
Abc.new.score
end
end
Remember the class name is always starts with capital letter.
In your abc.rb model file:
class Abc < ActiveRecord::Base
def self.score
sum = 10
end
end
Now you can access score method using Model name anywhere like.
class FirstController < ApplicationController
def get_score
Abc.score # you will get 10 here
end
end
scoreusing any object of classabc.