startUpload abstract method
Starts a file upload operation in the background.
The upload continues even if the app moves to the background. Progress can be tracked using getUploadProgress.
Parameters:
filePath: Local path of the file to uploaduploadUrl: The URL where the file should be uploaded toheaders: Optional HTTP headers to include in the requestfields: Optional form fields to include in the multipart request
Returns a task ID string that can be used to track progress or cancel the task.
Throws an Exception if the upload fails to start.
Implementation
Future<String> startUpload({
required String filePath,
required String uploadUrl,
Map<String, String>? headers,
Map<String, String>? fields,
});