Question

帮助者应该返回一个google api调用，但它会向控制台输出undefined一次，并且在获得响应时不会更新：

onCreated模板：

this.distances = new ReactiveDict('restDistances');

助手：

distanceIs: function (destination, id){
    var origin = Session.get('userLatLng');
    Tracker.autorun(function(){
        console.log(123);
        console.log(Blaze._globalHelpers.getDistance(Template.instance().distances, id, origin, destination));
        return Blaze._globalHelpers.getDistance(Template.instance().distances, id, origin, destination);
});

}

Template.registerHelper('getDistance', function(template, id, origin, destination){
  var map;
  var directionsDisplay;
  var directionsService;
  directionsDisplay = new google.maps.DirectionsRenderer;
  directionsService = new google.maps.DirectionsService;
  directionsDisplay.setMap(map);
  directionsService.route({
    origin: {lat: origin[0], lng: origin[1]},
    destination: {lat: destination[1], lng: destination[0]},
    travelMode: google.maps.TravelMode["DRIVING"]
}, function (response, status) {
    if(status == google.maps.DirectionsStatus.OK) {
      directionsDisplay.setDirections(response);
      directionsDisplay.setOptions({suppressMarkers: true});
      var distanceinmeter = (response.routes[0].legs[0].distance.value);
      var timeInMinutes = response.routes[0].legs[0].duration.value;
      console.log(distanceinmeter); //OK
      template.set(id, distanceinmeter );
      Tracker.autorun(function(){
        console.log(template.get(id));
        return template.get(id);
      });
    } else {
      console.log('rout not found');
    }
  })
});

Answer 1

让我们尝试以下方法 - 您甚至不需要Tracker.autorun()。

Template.myTemplate.onCreated(function(){
  this.distances = new ReactiveDict('restDistances');
});

Template.myTemplate.helpers({
  distanceIs: function (destination, id){
    const origin = Session.get('userLatLng');
    Blaze._globalHelpers.getDistance(Template.instance(), id, origin, destination);
    // the reactive var will automatically get updated when it is set from the
    // callback of directionsService.route()
    return Template.instance().distances.get('restDistances);
  }
});

Template.registerHelper('getDistance', function(template, id, origin, destination){
  var map, directionsDisplay, directionsService;
  directionsDisplay = new google.maps.DirectionsRenderer;
  directionsService = new google.maps.DirectionsService;

  directionsDisplay.setMap(map);
  directionsService.route({
    origin: {lat: origin[0], lng: origin[1]},
    destination: {lat: destination[1], lng: destination[0]},
    travelMode: google.maps.TravelMode["DRIVING"]
}, function (response, status) {

    if (status == google.maps.DirectionsStatus.OK) {
      directionsDisplay.setDirections(response);
      directionsDisplay.setOptions({suppressMarkers: true});
      // set the reactive var to the desired value
      template.distances.set('restDistances', response.routes[0].legs[0].distance.value);
      // there is no need to return here since it would be to the 
      // directionsServices.route callback and not the outer function

    } else {
      console.log('route not found');
    }
  })
});

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1 个答案: