Building a dynamic query using recursion

I interpret that document as describing a different structure where both and and or take the terms they apply to in a list. For your example, start by writing the expression with explicit parentheses:

(a == 1 and (b == 4 and c == 3)) or (d == 2)

Rules:

• %{variable_name: %{eq: value}} corresponds to variable_name == value
• %{var1: %{eq: v1}, var2: %{eq: v2}} corresponds to (var1 == v1) and (var2 == v2)
• %{and: [X, Y, Z]} corresponds to the expression (X and (Y and Z))
• %{or: [X, Y, Z]} corresponds to the expression (X or (Y or Z))

so

%{
  a: %{eq: 1},
  b: %{eq: 4},
  c: %{eq: 3}
}

corresponds to (a == 1 and (b == 4 and c == 3)). So finally

%{
  or: [
    %{
      a: %{eq: 1},
      b: %{eq: 4},
      c: %{eq: 3}
    },
    %{
      d: %{eq: 2}
    }
  ]
}

corresponds to the original expression.

The recursion you’ll need to turn the map above into Ecto operations is the derivation in reverse. You’ll likely want to use explicit recursion for this, as it’s a depth-first traversal of the input.

Thanks Matt for the reply! So it’s almost like restructuring the input into a format that makes it easier to evaluate. I’ll give that a shot.

Just wanted to update and say thank you for taking your time and input! I was able to get something working (after lots of head banging ).

I’ll leave a repl.it here in case someone finds it helpful/useful and maybe even improve it.