CODEWITHSUNDEEP
ruby-on-rails
user3868832
user3868832

Reputation: 620

Rails 4 override a model attribute with parent attribute

What is the best way to achieve the following in Rails 4? Parent and child model have the same attribute. If child model hasn't set said attribute then it inherits from the parent, otherwise, it renders its own value.

I tried to create a method in the child method with the same name as the model attribute to do the logic, but that causes a stack level too deep error.

  def age_of_seniority
    age_of_seniority.present? ? age_of_seniority : borough.age_of_seniority
  end

Update

I don't want to change the method name, I would like to be able to access it as a normal attribute

Upvotes: 3

Views: 487

Answers (3)

Rajdeep Singh
Rajdeep Singh

Reputation: 17834

You can do this using read_attribute

def age_of_seniority
  read_attribute(:age_of_seniority) || borough.age_of_seniority
end

Upvotes: 3

Headshota
Headshota

Reputation: 21439

You are recursively calling the method from within the method, this of course will cause a stack overflow.

def age_of_seniority
    age_of_seniority.present? ? age_of_seniority : borough.age_of_seniority
end

If the age_of_seniority is stored in the instance variable, you access it with:

@age_of_seniority

So in your code:

def age_of_seniority
  @age_of_seniority.present? ? @age_of_seniority : borough.age_of_seniority
end

And to call the overrided method from parent, you can just use super. not quite sure what's borough.age_of_seniority doing.

Upvotes: 0

Yule
Yule

Reputation: 9764

Call super:

def seniority_age
  super || borough.age_of_seniority
end

A simple example:

class Parent     

  attr_accessor :seniority_age     

end     

class Child < Parent     

  def seniority_age     
    super||'foo'     
  end     

end     

c = Child.new    
puts c.seniority_age    
c.seniority_age = "bar"     
puts c.seniority_age

returns:

foo

bar

Upvotes: 1

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