FQL recursive function to get nested documents

explanation.md

This is how you'd call the function:

Call(Function("GetNestedDocument"), [Ref(Collection("SomeCollection"), "264260207986606612"), 0, 3])

Parameters:

• A Ref of a document.
• Current depth. Since AFAIK we cannot have default values in Lambda we need to pass 0 for the first level.
• Max depth. The max number of levels the recursive function will go.

query.js

CreateFunction({
  name: "GetNestedDocument",
  body: Query(
    Lambda(
      ["documentRef", "depth", "maxDepth"],
      Let(
        {
          document: Get(Var("documentRef")),
          documentDataArray: ToArray(Select(["data"], Var("document"))),
          nextDepth: Add(Var("depth"), 1)
        },
        {
          ref: Select(["ref"],Var("document")),
          ts: Select(["ts"],Var("document")),
          data: ToObject(
            Map(
              Var("documentDataArray"),
              Lambda(
                ["key","value"],
                If(
                  And(
                    IsRef(Var("value")),
                    LTE(Var("nextDepth"),Var("maxDepth"))
                  ),
                  [
                    Var("key"),
                    Call(Function("GetNestedDocument"), [Var("value"), Var("nextDepth") ,Var("maxDepth")])
                  ],
                  [Var("key"), Var("value")]
                )
              )
            )
          )
        }
      )
    )
  )
})