How to use data binding in a server content editor?

Hello,

I have a problem using data binding in a server content editor because it’s expecting string. is there anything that I have to write to make data bindings work?
EDIT: putting it between quotes worked, but it becomes string while I need it as number

[
  {
    "$geoNear": {
      "near": {
        "type": "Point",
        "coordinates": [
          {{$_GET.lng}}, <-------- Expecting 'STRING', '}', got '{'
          {{$_GET.lat}}  <-------- same
        ]
      }, ...