How do I pass query parameters using angular.js

I am trying to pass parameters for a cypher query. I have stepped through the sequence to xhr.send() and am passing it this data:

{"query":"match (U:User {UserID: {UID}})-[:HAS_ROLES]->(R: Roles) return R.Roles as Roles, {IDX} as indx","params":"{UID : \"0012\" ,IDX : 0} "}

Wireshark shows the data being sent to Neo4j as this:

Object Member Key: "query" String value: Member Key: "params" Object

Every POST I send has an empty params object, so clearly the way I am passing this data is not correct. How do I populate the params object?

I am using the ANNE stack.

Michael D. Spence Mockingbird Data Systems, Inc.

            function runAdhocQueryParams(query,myparams) {
                var call = $http({
                    method: 'POST',
                    data: { query: query, params: myparams },
                    url: '/api/runAdhocQuery',
                    headers: { 'Content-Type': 'application/json' }
                });

                return $q.when(call);
            }

    query is
    match (U:User {UserID: {UID}})-[:HAS_ROLES]->(R: Roles) return R.Roles as Roles, {IDX} as indx

    myparams is (in JSON)

    {
      "UID": "0012",
      "IDX": 0
    }