Querying for huge number of keys from rails mongoid

Question

I have a rails app running on mongo. There is one Document that I need to query to perform a big calculation. The list of keys is huge like 50 plus.

I will be writing the calculation method in the model itself.

Since the number of keys is huge if I keep assigning the value of key to a local variable and use them, I would have to create 50 plus local variables. It would look like follows:

def get_score
  record = Model.last
  a1 = record['k1'],
  a2 = record['k2'],
  a3 = record['k3'] 
  ##---so--on 50 plus keys
  #formulae. Where I will be using the a1...a50 variables to calculate.
end

This would make the method unnecessarily look huge and wont look efficient at all. Is there a way where I can add these keys into a file or hash and map and call those keys on the model at a once?

Answer 1

To avoid repeated hash accesses, you could do:

hash={'a1'=>1,'a2'=>2}
eval (1..2).map { |i| "@a#{i} = hash['a#{i}'];" }.join

This gives you @a1 and @a2 .

I can't figure out how to create local variables programmatically. You can write to a binding but not to the local scope it seems.