Question

Let’s say I’ve got a table that I’m trying to convert. Its got column names Item1, Item2… Item25. I don’t have control over the column names, I’m converting from this into a better structure.

Because there’s a pattern to the naming convention, I can create the column names on the fly. The problem is that when I try to use my variable as an object key, it gets passed through as a literal instead of the contents of the variable.

For instance, this works:

if !order.item1.empty?
  OrderItem.create(
  :item => order.item1,
  :quantity => order.qty1,
  :price => order.price1
)

But rather than make 25 variations of that by hand, I’d like to do something like

i = 1
while i < 25
    item_ref = "item" + i.to_s
    if !order.item_ref.empty?
    OrderItem.create(
        :item => order.item_ref,
        etc...)
    i += 1
    end
end

But of course this doesn’t work. Rails tries to look up order.item_ref instead of order.item1, which doesn’t exist.

I’ve hit this issue a couple of times on various projects, any thoughts?

Answer 1

order.send item_ref; Also, use 25.times do |i| (starts at 0) or (1..25).each do |i| rather than your own loop.