javascript - 如何检查 firebase data() 中地理点字段上的空值

Question

我正在添加用户地理点，我想在将数据推送到数组之前检查 snapShot.data().location.geopoint 是否为空，但我不断收到以下错误:

ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'geopoint' of undefined
TypeError: Cannot read property 'geopoint' of undefined
 

这是实际的代码吗？

query.get()
            .then(list => {
              list.forEach(snapShot => {
                let userLat = (snapShot.data().location.geopoint.latitude > 0) ? snapShot.data().location.geopoint.latitude : 0;
                let userLong = (snapShot.data().location.geopoint.longitude > 0) ? snapShot.data().location.geopoint.longitude : 0;

                console.log('use lat long', userLat, userLong);

                let distance = this.geo.distance(this.geo.point(myLat, myLong), this.geo.point(userLat, userLong));
                if (distance <= this.userSettings.distance.upper) {
                  this.userInfo.push({
                    userId: snapShot.data().userId,
                    displayName: snapShot.data().displayName,
                  });
                }
              });
            })

鉴于它提示我添加的实际空值检查，我将如何检查地理点中的空值:

            let userLat = (snapShot.data().location.geopoint.latitude > 0) ? snapShot.data().location.geopoint.latitude : 0;

Answer 1

您可以使用 snapshot.get(fieldPath) API ( docs ) 并执行以下操作:

let userLat = 0;
let userLong = 0;

if (snapShot.get("location.geopoint")) {
  userLat = snapShot.get("location.geopoint").latitude;
  userLong = snapShot.get("location.geopoint").longitude;
}