flutter firebase image upload takes time to get file url-CodePudding

i'm trying to upload an image to the cloud firestore and the firebase storage. I'm saving the image url in a variable called imgUrl, this variable is later on passed inside a function called addIntervention(). The problem is that the upload task takes few time so if I upload and click the save button directly, imgUrl will be having null value cus the image is still getting uploaded.

Here is my code:

IconButton(
                        icon: Icon(
                          Icons.image,
                          color: Palette.primaryColor,
                        ),
                        onPressed: () async {
                          ImagePicker imagePicker = ImagePicker();
                          XFile? file = await imagePicker.pickImage(
                              source: ImageSource.gallery);

                          if (file == null) return;

                          Reference referenceRoot =
                              FirebaseStorage.instance.ref();
                          Reference dirImages =
                              referenceRoot.child("iv_images");
                          Reference imgToUpload = dirImages.child(file.name);

                          try {
                            await imgToUpload.putFile(File(file.path));

                            var x = imgUrl = await imgToUpload.getDownloadURL();
                            imgUrl = x;
                          } catch (e) {}
                        },
                      ),

And for the button I took this snippet:

if (imgUrl.isEmpty) {
                                 QuickAlert.show(
                                    context: context,
                                    type: QuickAlertType.error,
                                    title: 'Error',
                                    text:
                                        'Please upload an image');
                              } else {
                                await addIntervention(
                                    imgUrl,
                                    etatLabel,
                                    numIntv,
                                    intervention,
                                    myPrice!,
                                    note,
                                    dateTime);

Noting that i'm using async/await for the save button as well, is there any way I can solve this? thanks in advance.

CodePudding user response：

You can try these tips:

First thing to make your upload time a lot less is to compress a picture, you don't have to compress the image till it gets blurry but a small amount of compression will significantly reduce your upload time. Also if a use selects an image then he/she may want to crop it too. So it will be better if you add that functionality too.

Luckily there's a package called image_cropper(link), which you can use to crop as well as for compressing your image.

If you don't want to show any loading indicator then you can directly pass the image to the next screen and run your processes in the background(which is called optimistic updating), but if you want to show a loading indicator then you can use this package called flutter_spinkit. It has a very large variety of loading indicators which you will love.
When a user clicks on a button, you can show a progress indicator on the button itself to indicate how much percent has been uploaded, has to be uploaded before the user can click on the button.

In the firebase, you can get percentage like this:

 Future getImage(BuildContext context) async {
    final picker = ImagePicker();
    final pickedFile = await picker.getImage(source: ImageSource.gallery);
    setState(() {
      _image = File(pickedFile.path);
    });
    StorageReference firebaseStorageRef = FirebaseStorage.instance.ref().child('profile/${Path.basename(_image.path)}}');
    StorageUploadTask uploadTask = firebaseStorageRef.putFile(_image);
    var dowurl = await (await uploadTask.onComplete).ref.getDownloadURL();   
     setState(() {    
       _imageURL = dowurl.toString();

     });

    print(_imageURL);
  } 

uploadTask.events.listen((event) {
      setState(() {
        _progress = event.snapshot.bytesTransferred.toDouble() /
            event.snapshot.totalByteCount.toDouble();
      });
    }).onError((error) {
      // do something to handle error
    });

Then you can display progress like this:

Text('Uploading ${(_progress * 100).toStringAsFixed(2)} %')