Is it possible to have a scope with optional arguments?

Question

Is it possible to write a scope with optional arguments so that i can call the scope with and without arguments?

Something like:

scope :with_optional_args,  lambda { |arg|
  where("table.name = ?", arg)
}

Model.with_optional_args('foo')
Model.with_optional_args

I can check in the lambda block if an arg is given (like described by Unixmonkey) but on calling the scope without an argument i got an ArgumentError: wrong number of arguments (0 for 1)

Answer 1

Ruby 1.9 extended blocks to have the same features as methods do (default values are among them):

scope :cheap, lambda{|max_price=20.0| where("price < ?", max_price)}

Call:

Model.cheap
Model.cheap(15)

Answer 2

Yes. Just use a * like you would in a method.

scope :print_args, lambda {|*args|
    puts args
}

Answer 3

I used scope :name, ->(arg1, arg2 = value) { ... } a few weeks ago, it worked well, if my memory's correct. To use with ruby 1.9+