How to add to array in Ruby

Question

I'm sure this is simple but I can't seem to get it:

Works:

@build1 = Booking.build_booking('2009-06-13',3,2,18314)
@build2 = Booking.build_booking('2009-06-13',3,4,18317)
@build = @build1 + @build2

What I want to work...

#for item in @cart.items do
#  @build << Booking.build_booking('2009-06-13',3,2,18314)
#end

Doesn't work either...

#(1..3).each do |i|
#  @build << Booking.build_booking('2009-06-13',3,2,18314)
#end

Solution 1

For the two iterating examples you'd need to set @build prior to calling << on it.

I'm not sure what build_booking is returning but if it's an array (I'm guessing from the first, working, example) then you'd probably want to add the result of build_booking to @build. E.g.

@build = []
for item in @cart.items do
  @build += Booking.build_booking('2009-06-13',3,2,18314)
end

Solution 2

I prefer using the wonderful array-methods that ruby has to offer over a for loop:

@build = @cart.items.map { |item| Booking.build_booking('2009-06-13',3,2,18314) }

Comments

[holden]

according to the console after the addition @build.class = Array as are @build1 and @build2

[holden]

ah perfect... i tried += as my first guess but forgot the Array.new!

[dylanfm]

This is probably a good place to use inject too. ruby-doc.org/core/classes/Enumerable.html#M003171

[tadman]

I think the approach of Magnar is better than most here, since it generates the array by converting cart items into bookings directly instead of explicitly declaring an array and then making incremental alterations using the += operator. Array#map or the alternative name Array#collect is a very powerful tool.

[James A. Rosen]

@dylanfm #inject would certainly work, but it's overkill; #map works just fine!