What is the proper way to check for existence of objects in Rails / Ruby?

Question

I have a lot of models and relations. Due to this fact, there is lot of calls in views/controllers, which look like this:

 @object.something.with_something.value 

Some part of the chain can end up being nil, which is perfectly ok. What is the proper/clean/fast way to check for the existence of the terminal object?

Is calling something like:

 @object.something.with_something.value if defined? @object.something.with_something.value 

Considered ok?

Answer 1

Natively, you'd need to use the && operator (not defined?), but this can get very verbose, very quickly.

So instead of doing this:

(@object && @object.something && @object.something.with_something &&
  @object.something.with_something.value)

You can do this when ActiveSupport is present:

@object.try(:something).try(:with_something).try(:value)

Or install the invocation construction kit and use its guarded evaluation tools:

Ick::Maybe.belongs_to YourClass
maybe(@object) { |obj| obj.something.with_something.value }