Is there a better way to declare this?
if current_user.received_replies.unread.count > 0 What I'm trying to do is match condition only if there's at least one unread object.
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3 Answers
unless current_user.received_replies.unread.empty? # ... end Or, if your if has an else, switch the cases (because unless/else is fugly as hell):
if current_user.received_replies.unread.empty? # ... else # ... end 
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I'd use:
if current_user.received_replies.unread.any? From the docs:
= Array.any? (from ruby core) === Implementation from Enumerable ------------------------------------------------------------------------------ enum.any? [{|obj| block } ] -> true or false ------------------------------------------------------------------------------ Passes each element of the collection to the given block. The method returns true if the block ever returns a value other than false or nil. If the block is not given, Ruby adds an implicit block of {|obj| obj} (that is any? will return true if at least one of the collection members is not false or nil. %w{ant bear cat}.any? {|word| word.length >= 3} #=> true %w{ant bear cat}.any? {|word| word.length >= 4} #=> true [ nil, true, 99 ].any? #=> true 
6 Comments
Niklas B.
That is not quite equivalent if the list contains falsy items. In the domain of
ActiveRecord it might be viable, but I've seen a lot confusion about this where people thought it was just the negation of empty?, which is not true in general.
Andrew Marshall
@NiklasB. Wow I never noticed that. Kind of nasty that
[false].any? is false.Niklas B.
@Andrew: Why wouldn't it be? Usually this function is to check if a predicate holds for any of the items, like in
[1,2,3].any? { |x| x > 2 }. It's kind of unfortunate that it also works without a block (I don't see where it would be useful).Andrew Marshall
@NiklasB. Well that's my point, the version without a block is misleading and doesn't immediately seem to convey its check for truthyness. I agree that it shouldn't exist.
the Tin Man
I find the non-block version quite useful, but then I know that my array will contain truthy elements. If you don't know what is in your array the block is great to provide deeper inspection of the elements. If I have a array of unknown element types, I think I have a bigger problem than whether
any? works without a block. |
This could be a little bit better :
unless current_user.received_replies.unread.empty? 