传递带有Google Maps Distance Matrix请求的标识符

Question

I'm trying to use Google's Distance Matrix Service to calculate the driving distance between Point A to Point B, then Point B to Point C and so on.

I realise the matrix system is designed to determine a different set of results, but it's my intention to make multiple separate requests consecutively. However, when I make a request, the asynchronous nature means that when it is returned, there is no way of knowing which request it was (Point A to B or Point B to C), especially as it reformats the address you give it initially, so even keeping an array of requests doesn't help, as the addresses sent don't match the ones received.

So my question is, is it possible to pass an identifier along with the request, so that you can keep track of which request corresponds to which address? I have tried the following:

var service = new google.maps.DistanceMatrixService();
            service.getDistanceMatrix(
            {
                origins: [address1],
                destinations: [address2],
                travelMode: google.maps.TravelMode.DRIVING,
                unitSystem: google.maps.UnitSystem.METRIC,
                uniqueIdentifier: 1
            }, someOtherName);

But the API doesn't like the "uniqueIdentifier" field being passed.

Thanks!

Answer 1

No. You can't do that. However, what you can do is push an identifier on the returned results object instead. In this example I've separated the code into a function and a call to that function, passing in an identifier as a parameter to the function, adding it to the results object, and picking it out of the data that's passed to the callback.

function getDistance(identifier, callback) {
  var service = new google.maps.DistanceMatrixService();
  service.getDistanceMatrix({
    origins: [address1],
    destinations: [address2],
    travelMode: google.maps.TravelMode.DRIVING,
    unitSystem: google.maps.UnitSystem.METRIC
  }, function (results) {
     results.identifier = identifier;
     callback(results);
  });
}

var identifier = 1;
getDistance(identifier, function (results) {
  console.log(results.identifier); // 1
});