Question

I have a Meeting model which has multiple Participants. Participant has a few boolean attributes: accepted, rejected ect. I would like check all participants of a meeting if their are all accepted == true.
Is there a quick way to check all boolean attributes of child objects similar to sum method (as in total_price = items.sum(&:price) )?

Answer 1

You could use count:

all_true = items.count(:conditions => [ 'bool_column = ?', true ]) == items.count

And if you don’t have NULLs to worry about in your boolean column:

all_true = items.count(:conditions => [ 'bool_column = ?', false ]) == 0

Or you could do it this way (as suggested by klochner) to get around the usual NULL problems and avoid a double count:

all_true = items.count(:conditions => [ 'bool_column = ? or bool_column is null', false ]) == 0

You could check several boolean columns at once too.