Question

I am looking for “elegant” way to check if given object is nil and it’s attribute is nil or empty. At the moment I have this check

response = foo.call() # some service call, no http code given :)
raise StandardError, "Response is not valid" if response.nil? || response['data'].nil? || reponse['data'].emtpy?

Is there more elegant way to do this, and avoid triple OR check? Wrap in begin/catch is not elegant way in case somebody would suggest that.

Answer 1

What about this?

data = response.try(:[], 'data')
raise Exception, "Response is not valid" if data.nil? || data.empty?

As @ksol correctly mentions in the comments, try helper comes from ActiveSupport. But it is not difficult at all to re-implement.

class Object
  def try method, *args
    if respond_to? method
      send method, *args
    else
      nil
    end
  end
end

class Foo
  def hello name
    "hello #{name}"
  end
end

f = Foo.new
f.try(:bar) # => nil
f.try(:hello, 'world') # => "hello world"
nil.try(:wat) # => nil

Alternatives

Here’s Object#andand if you don’t want to drag along the entire activesupport and don’t feel like writing code that’s already written.

data = response.andand['data']
raise Exception, "Response is not valid" if data.nil? || data.empty?