AQL（ArangoDb）中的递归遍历

Question

When traversing trees or graphs (in my case a DAG), I often see the use for recursion. Is this supported or planned to be supported in AQL in the near future?

Say I have an AQL query or sub-query (a traversal) and would like to call it recursively. Could it be done wrapped in Foxx perhaps?

Answer 1

as things stand there is no recursion in AQL itself. Recursion could be wrapped in Foxx using recursion in JavaScript, eg:

var recursion = function(last) {
  if (last.length > 3) {
    return last;
  }
  return recursion(db._query("<some AQL query>", {last: last}));
}


controller.get("/recursive", function (req, res) {
  res.json(recursion(["a","b","c"]));
}

For graph traversals we have plans to extend AQL with some operators to define "For All" or "For Any" filters on the traversal path. Which could handle many patters directly. The syntax will probably look like:

FOR v,e,p IN 1..12 OUTBOUND "vertex/start" edges
  FILTER p.vertices[*].age ALL >= 35
  RETURN v

Which will than find all paths of length 1 to 12 where all vertices have the age attribute greater or equal to 35 .

Hope this helps.