firebase - 无法将网址保存在Firestore中

Question

我正在使用下面的代码将flutter应用程序中的选定图像上载到Firebase存储，这已成功完成，但是我无法将图片的url保存在firestore中，在这种情况下我在做什么错？

您可以在下面的代码中看到尝试存储URL的尝试。请指导我该如何纠正？

Future uploadFile(String uid) async {

    StorageReference reference = FirebaseStorage.instance.ref().child('profile_pic/$uid');
    StorageUploadTask uploadTask = reference.putFile(avatarImageFile);
    StorageTaskSnapshot storageTaskSnapshot;
    uploadTask.onComplete.then((value) {
      if (value.error == null) {
        storageTaskSnapshot = value;
        storageTaskSnapshot.ref.getDownloadURL().then((downloadUrl) {
          setState(() {
            photoUrl = downloadUrl;

          });
          Firestore.instance
              .collection('users')
              .document(uid)
              .setData({ 'photoUrl': photoUrl}).then((data) async {
            setState(() {
              isLoading = false;
            });
            Fluttertoast.showToast(msg: "Upload success");
          }).catchError((err) {
            setState(() {
              isLoading = false;
            });
            Fluttertoast.showToast(msg: err.toString());
          });
        }, onError: (err) {
          setState(() {
            isLoading = false;
          });
          Fluttertoast.showToast(msg: 'This file is not an image');
        });
      } else {
        setState(() {
          isLoading = false;
        });
        Fluttertoast.showToast(msg: 'This file is not an image');
      }
    }, onError: (err) {
      setState(() {
        isLoading = false;
      });
      Fluttertoast.showToast(msg: err.toString());
    });
  }

Answer 1

该方法已经声明为异步方法，因此请尝试使用await而不是then():

Future uploadFile(String uid) async {

    StorageReference reference = FirebaseStorage.instance.ref().child('profile_pic/$uid');
    StorageTaskSnapshot snapshot = await reference.putFile(avatarImageFile).onComplete;
      if (snapshot.error == null) {
        final String photoUrl = await snapshot.ref.getDownloadURL();
           Firestore.instance
              .collection('users')
              .document(uid)
              .setData({ 'photoUrl': photoUrl}).then((data) async {
            setState(() {
              isLoading = false;
            });
            Fluttertoast.showToast(msg: "Upload success");
          }).catchError((err) {
            setState(() {
              isLoading = false;
            });
            Fluttertoast.showToast(msg: err.toString());
          });
        }, onError: (err) {
          setState(() {
            isLoading = false;
          });
          Fluttertoast.showToast(msg: 'This file is not an image');
        });
      } else {
        setState(() {
          isLoading = false;
        });
        Fluttertoast.showToast(msg: 'This file is not an image');
      }
    }, onError: (err) {
      setState(() {
        isLoading = false;
      });
      Fluttertoast.showToast(msg: err.toString());
    });
  }

现在，当使用 await时，您将能够首先检索该URL，然后将其保存在Firestore中。