How to convert type String to type File in Flutter

Question

I am running a project with flutter-web

This time is first time doing project with flutter-web. and now i just knew that flutter web doesn't supports Dart:io

So i am trying to use dart.html and... it is quite different compare to dart:io

uploadImage(ReservationPvd reservationPvd) async {
    final XFile? photo = await ImagePicker().pickImage(source: ImageSource.gallery);
    File image = File(photo!.path);
    MultipartFile imageFile = await MultipartFile.fromFile(photo.path);
    reservationPvd.updateInfo('image', image);
    reservationPvd.updateInfo('imageFile', imageFile);
  }

this following code is the code that i've used in my other project with flutter. and I need to save this File to Type File and MultipartFile

File image = File(photo!.path);

and this following code gives an error message, and it says

The argument type 'String' can't be assigned to the parameter type 'List<Object>'

i have googled for a 3 days but i really can't solve this problem...

does anyone knows how to upload fine ways to upload in flutter-web?

error message says Unsupported operation: MultipartFile is only supported where dart:io is available. — Noah_J.C_Lee
– Noah_J.C_Lee, Commented Aug 22, 2022 at 13:09

cloudpham93 · Accepted Answer · 2022-08-22 14:35:11Z

1

I have flutter-web project and it use MultipartFile.fromBytes not MultipartFile.fromFile. Because in flutter-web you can't get File from path. Try this:

uploadImage(ReservationPvd reservationPvd) async {
    final XFile? photo = await ImagePicker().pickImage(source: ImageSource.gallery);

    MultipartFile imageFile = MultipartFile.fromBytes(await photo!.readAsBytes());
    
    reservationPvd.updateInfo('image', image);
    reservationPvd.updateInfo('imageFile', imageFile);
  }

edited Aug 22, 2022 at 14:35

answered Aug 22, 2022 at 14:30

cloudpham93

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3 Comments

Noah_J.C_Lee Over a year ago

oh this worked but problem is now i can't save image to a server

cloudpham93 Over a year ago

It work normal for me. Check your upload code

Noah_J.C_Lee Over a year ago

worked perfect realy thx

fravolt · Accepted Answer · 2022-08-22 12:57:27Z

1

I suspect your File class may be imported from the wrong dependency. It should use File from dart:io like so:

import 'dart:io';

And it's likely you're currently using dart:html:

import 'dart:html';

Auto import suggests dart:html over dart:io for me as well, so this is the most likely cause I think.

answered Aug 22, 2022 at 12:57

fravolt

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2 Comments

Noah_J.C_Lee Over a year ago

but i can't use dart:io... because it is flutter-web...

fravolt Over a year ago

Ah of course, my bad. I don't suppose using an Image.network(...) instead of File is going to help you here either?

Onyema_Anthony · Accepted Answer · 2022-08-22 14:15:55Z

1

to get around dart io not supported in web after you pick the image instead of File(file.path) you say file.readAsBytes(); the you store the output of file.readAsBytes() in a Uint8List variable. when you want to display the images you use MemoryImage() provided in flutter

answered Aug 22, 2022 at 14:15

Onyema_Anthony

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