dart - Uploading Screenshots to Firebase with Flutter

Question

I want to upload the screenshot image to Firestore, but I am having some null errors,

Future uploadImagetoFirebase() async {
await screenshotController.capture().then((value) => (File image) {
      _screenshot = image;
    });

String fileName = _screenshot.path;
Reference firebaseStorageRef =
    FirebaseStorage.instance.ref().child('orders/$fileName');
UploadTask uploadTask = firebaseStorageRef.putFile(_screenshot);
TaskSnapshot taskSnapshot = await uploadTask;
taskSnapshot.ref.getDownloadURL().then((value) => print('Done: $value'));


}

I am calling it with button like this:

 onPressed: () async {
            await uploadImagetoFirebase(); }  

This is the error stack:

 flutter ( 5143): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: NoSuchMethodError: The getter 'path' was called on null.
E/flutter ( 5143): Receiver: null
E/flutter ( 5143): Tried calling: path
E/flutter ( 5143): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
E/flutter ( 5143): #1      _CartState.uploadImagetoFirebase
package:CWCFlutter/model/cart.dart:88
E/flutter ( 5143): <asynchronous suspension>
E/flutter ( 5143): #2      _CartState.build.<anonymous closure>.<anonymous closure>.<anonymous closure>.<anonymous closure>
package:CWCFlutter/model/cart.dart:310
E/flutter ( 5143): #3      _InkResponseState._handleTap
package:flutter/…/material/ink_well.dart:993
E/flutter ( 5143): #4      _InkResponseState.build.<anonymous closure>
package:flutter/…/material/ink_well.dart:1111
E/flutter ( 5143): #5      GestureRecognizer.invokeCallback
package:flutter/…/gestures/recognizer.dart:183
E/flutter ( 5143): #6      TapGestureRecognizer.handleTapUp
package:flutter/…/gestures/tap.dart:598
E/flutter ( 5143): #7      BaseTapGestureRecognizer._checkUp
package:flutter/…/gestures/tap.dart:287
E/flutter ( 5143): #8      BaseTapGestureRecognizer.handlePrimaryPointer
package:flutter/…/gestures/tap.dart:222
E/flutter ( 5143): #9      PrimaryPointerGestureRecognizer.handleEvent
package:flutter/…/gestures/recognizer.dart:476
E/flutter ( 5143): #10     PointerRouter._dispatch
package:flutter/…/gestures/pointer_router.dart:77
E/flutter ( 5143): #11     PointerRouter._dispatchEventToRoutes.<anonymous closure>
package:flutter/…/gestures/pointer_router.dart:122
E/flutter ( 5143): #12     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
E/flutter ( 5143): #13     PointerRouter._dispatchEventToRoutes
package:flutter/…/gestures/pointer_router.dart:120
E/flutter ( 5143): #14     PointerRouter.route
package:flutter/…/gestures/pointer_router.dart:106
E/flutter ( 5143): #15     GestureBinding.handleEvent
package:flutter/…/gestures/binding.dart:358
E/flutter ( 5143): #16     GestureBinding.dispatchEvent
package:flutter/…/gestures/binding.dart:338
E/flutter ( 5143): #17     RendererBinding.dispatchEvent
package:flutter/…/rendering/binding.dart:267
E/flutter ( 5143): #18     GestureBinding._handlePointerEvent
package:flutter/…/gestures/binding.dart:295
E/flutter ( 5143): #19     GestureBinding._flushPointerEventQueue
package:flutter/…/gestures/binding.dart:240
E/flutter ( 5143): #20     GestureBinding._handlePointerDataPacket
package:flutter/…/gestures/binding.dart:213
E/flutter ( 5143): #21     _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter ( 5143): #22     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 5143): #23     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 5143): #24     _invoke1 (dart:ui/hooks.dart:265:10)
E/flutter ( 5143): #25     _dispatchPointerDataPacket (dart:ui/hooks.dart:174:5)

I am not sure how path was called on null, any ideas? Basically I await for the app to take a screenshot, then add that image in _screenshot File variable, then try to store it in 'orders' folder in Firestore. I have searched for answers, and they say you need to initialize Firestore somewhere, but I am not sure where that would be, I have only worked with older versions, and not sure how to do all things in the newer ones. Thank you!

I have tried setting the state as well, but getting the same error:

Future uploadImagetoFirebase() async {
await screenshotController.capture().then((value) => (File image) {
    setState(() {
              _screenshot = image;
          });     
});

What I came up with that seems to work as a solution

    Future<String> uploadImagetoFirebase2() async {
    File img = await screenshotController.capture();
    setState(() {
      _screenshot = img;
    });
//change filename not to be path, but something else short
    String fileName = img.path;

    Reference firebaseStorageRef =
        FirebaseStorage.instance.ref().child('orders/$fileName');
    UploadTask uploadTask = firebaseStorageRef.putFile(_screenshot);
    TaskSnapshot taskSnapshot = (await uploadTask);
    String uri = await taskSnapshot.ref.getDownloadURL();
    print(uri);
    return uri;
  }

question from:https://stackoverflow.com/questions/65906903/uploading-screenshots-to-firebase-with-flutter

Answer 1

try this;

Future<String> uploadImagetoFirebase() async {
File img = await screenshotController.capture();

String fileName = img.path;

Reference firebaseStorageRef =
    FirebaseStorage.instance.ref().child('orders/$fileName');
UploadTask uploadTask = firebaseStorageRef.putFile(_screenshot);
TaskSnapshot taskSnapshot = (await uploadTask);
String uri = await taskSnapshot.ref.getDownloadURL();
print(uri);
return uri;
}