无法在地理编码函数内分配组件变量值

Question

GetLocation(address: string) {
  var geocoder = new google.maps.Geocoder();
  geocoder.geocode({ 'address': address }, (results, status) => {
    if (status == google.maps.GeocoderStatus.OK) {
      this.lat = results[0].geometry.location.lat(); 
      this.lng = results[0].geometry.location.lng();   <== this.lat value is undefined
    }
    else {
      alert("Something went wrong : " + status);
    }
  });
}

这里我无法在地理编码函数中分配组件级别变量 'lat' 和 'lng' 的值。仅供参考：其中结果的位置对象中有值，但在分配该值后它仍然未定义我不知道为什么？

Answer 1

import { Component, OnInit, NgZone } from '@angular/core';  <= 1. I have to import NgZone

constructor(private ngZone: NgZone) { }  <= 2. declared it here

ngOnInit() { }

GetLocation(address: string) {
  var geocoder = new google.maps.Geocoder();
  geocoder.geocode({ 'address': address }, (results, status) => this.ngZone.run(() => { <= 3. and used it here
    if (status == google.maps.GeocoderStatus.OK) {
      this.lat = results[0].geometry.location.lat();
      this.lng = results[0].geometry.location.lng();
    }
    else {
      alert("Something went wrong : " + status);
    }
  }));
}

我找到了解决方案。我必须从 '@angular/core' 导入 NgZone 并在回调函数中使用 this.ngZone.run() 函数，如 3.hint.

无法在地理编码函数内分配组件变量值

Cannot assign component variable value inside geocode function

google-maps

google-geocoder

angular6