Question

I have a model for assessment criteria which has a :label field containing string values like

//P1
//P2
//P3
//P4
//M1
//M2
//M3
//M4
//D1
//D2
//D3
//D4
//etc.

I want to order my queries by this field but looking at the number first and then in the order of P, M, D for each number, resulting in:

//P1
//M1
//D1
//P2
//M2
//D2
//P3
//M3
//D3
//P4
//M4
//D4
//etc.

How could I achieve that?

Answer 1

Try this:

sort_order = "PMD"

%w(//P1 //P2 //P3 //P4 //M1 //M2 //M3 //M4 //D1 //D2 //D3 //D4 ).sort_by do  |str| 
  str.gsub(/^.{3}/, '') + sort_order.index(str[2]).to_s
end