Tell the end of a .each loop in ruby
Ruby on-RailsRubyLoopsEachRuby on-Rails Problem Overview
If i have a loop such as
users.each do |u|
#some code
end
Where users is a hash of multiple users. What's the easiest conditional logic to see if you are on the last user in the users hash and only want to execute specific code for that last user so something like
users.each do |u|
#code for everyone
#conditional code for last user
#code for the last user
end
end
Ruby on-Rails Solutions
Solution 1 - Ruby on-Rails
users.each_with_index do |u, index|
# some code
if index == users.size - 1
# code for the last user
end
end
Solution 2 - Ruby on-Rails
If it's an either/or situation, where you're applying some code to all but the last user and then some unique code to only the last user, one of the other solutions might be more appropriate.
However, you seem to be running the same code for all users, and some additional code for the last user. If that's the case, this seems more correct, and more clearly states your intent:
users.each do |u|
#code for everyone
end
users.last.do_stuff() # code for last user
Solution 3 - Ruby on-Rails
I think a best approach is:
users.each do |u|
#code for everyone
if u.equal?(users.last)
#code for the last user
end
end
Solution 4 - Ruby on-Rails
Did you tried each_with_index
?
users.each_with_index do |u, i|
if users.size-1 == i
#code for last items
end
end
Solution 5 - Ruby on-Rails
h = { :a => :aa, :b => :bb }
h.each_with_index do |(k,v), i|
puts ' Put last element logic here' if i == h.size - 1
end
Solution 6 - Ruby on-Rails
Another solution is to rescue from StopIteration:
user_list = users.each
begin
while true do
user = user_list.next
user.do_something
end
rescue StopIteration
user.do_something
end
Solution 7 - Ruby on-Rails
You can use @meager's approach also for an either/or situation, where you're applying some code to all but the last user and then some unique code to only the last user.
users[0..-2].each do |u|
#code for everyone except the last one, if the array size is 1 it gets never executed
end
users.last.do_stuff() # code for last user
This way you don't need a conditional!
Solution 8 - Ruby on-Rails
Sometimes I find it better to separate the logic to two parts, one for all users and one for the last one. So I would do something like this:
users[0...-1].each do |user|
method_for_all_users user
end
method_for_all_users users.last
method_for_last_user users.last
Solution 9 - Ruby on-Rails
There are no last method for hash for some versions of ruby
h = { :a => :aa, :b => :bb }
last_key = h.keys.last
h.each do |k,v|
puts "Put last key #{k} and last value #{v}" if last_key == k
end