Rails / ActiveRecord - 我怎样才能使这更简洁？

Question

In my view I have a line such as the following:

<%= @house.person.phone_number unless @house.person.nil?  %>

It seems like I have to do this sort of thing a lot as some fields are nullable.

Is there a better way to write this?

I could handle it at the model layer but thats not really model layer functionality, as I understand.

Answer 1

You can use delegate method supported by active record.

delegate :phone_number, :to => :person, :allow_nil => true

And call @house.phone_number directly, avoiding the person middleman too. If phone is nil, this will also return nil.

Answer 2

你可以使用@house.person.try(:phone_number)

Answer 3

These Strongly-Worded Suggestion of Demeter -type issues can certainly be wrapped up in the model by wrapping up the Person 's methods in the House , exposing less information in the process.

def person_phone_number
    @person.phone_number || ""
end

Kind of clunky; you could also meta-program them in to place.

Or create helpers, or a combo of both. This is a typical issue, and IMO there's nothing wrong with wrapping it up in the containing model.