Undefined value return by Angular - angularjs

Question

I have a Angular function to retrieve taxi annonces and i need to calculate the distance between the user connected et the author of annonce then I have something like this :
In my HTML :
<main class="main list_page" ng-controller="taxiRechercheCtrl" ng-init="loadRecherche()">
In Angular :
myApp.controller("taxiRechercheCtrl", ['$scope','$http','$location', 'TaxiService', 'UserService', function($scope, $http, $location, TaxiService, UserService){
$scope.loadRecherche = function(){
UserService.getPosition().then(function(position){
TaxiService.find($scope.recherche).then(function(response){
$scope.annonces = response.annonces;
for(var i=0;i<$scope.annonces.length;i++){
$scope.annonces[i].Distance = my calculate distance
}
}, function(err){
console.log(err);
});
}, function(err){
console.log(err);
});
};
$scope.calculeDistanceGoogle = function(origin, destination){
var origin1 = new google.maps.LatLng(origin.Latitude, origin.Longitude);
var destination1 = new google.maps.LatLng(destination.latitude, destination.longitude);
var args = {
origins: [origin1],
destinations: [destination1],
travelMode: 'DRIVING'
};
var service = new google.maps.DistanceMatrixService();
service.getDistanceMatrix(args, function(response, status) {
var elt = response.rows[0].elements[0];
$scope.distanceTxt = elt.distance.text;
});
return $scope.distanceTxt;
}
}
In $scope.annonces[i].Distance = my calculate distance, I want the distance value returned by my calculeDistanceGoogle function.
I tried :
$scope.calculeDistanceGoogle($scope.annonces[i].Ville, response.position).then(function(response){
console.log(response);
}, function(err){
console.log(err);
});
but I have the error : $scope.calculeDistanceGoogle(...).then is not a function.
I tried use $scope.distanceTxt variable, I try directly :
var myposition = $scope.calculeDistanceGoogle($scope.annonces[i].Ville, response.position);

Answer 1

The $scope.calculeDistanceGoogle(...) is not a function that return a Promise, so you can't call .then(...) clause.
And then, this code is wrong:
service.getDistanceMatrix(args, function(response, status) {
var elt = response.rows[0].elements[0];
$scope.distanceTxt = elt.distance.text;
});
return $scope.distanceTxt;
because probabily that service is asynchronous.
My suggestion is return a promise with the value of distanceTxt as data (add error if present on the promise too).