Rails 3: Avoiding nested ifs when testing for nested parameters

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 standa开发者_StackOverflowrd (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...

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For the second one you can use and statements.

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