Question

In rails, if I test for a nested parameter and there is no :parent assigned, it will throw an error. So, for example,

   params[:page][:childpage][:grandchildpage].present?

throws ‘You have a nil object where you didn’t expect it’ if there’s no :page or :childpage. Similarly,

   demopage = @page.childpage.grandchildpage.present?

throws something similar.

The solution which dare not show it’s face is a whole bunch of nested if statements, which obviously isn’t good enough. So, the question is…what’s the standard (elegant) way of returning false instead of throwing an error should any parent element be blank? A rescue method, or is there something better?

I’m guessing this is pretty common, just wondering what the standard solution is.

Cheers…

Answer 1

For the second one you can use and statements.

demopage = @page &&
  @page.childpage &&
  @page.childpage.grandchildpage &&
  @page.childpage.grandchildpage.present?