background_downloader

Issue #189 related to resume on Android versions prior to S, and to expediting a task prior to S

See https://stackoverflow.com/a/68468786/4172761

Fixes issue with parsing priority from JSON Fixes issue with setting expedited for Android versions prior to S. This effectively ignores priority (expedited) scheduling for tasks prior to Android S and defaults to normal.

Minor improvements to TaskQueue and MemoryTaskQueue

Bug fix for web compilation

Task priority levels

The Task.priority field must be 0 <= priority <= 10 with 0 being the highest priority, and defaults to 5. On Desktop and iOS all priority levels are supported. On Android, priority levels <5 are handled as 'expedited', and >=5 is handled as a normal task.

Task queues

Once you enqueue a task with the FileDownloader it is added to an internal queue that is managed by the native platform you're running on (e.g. Android). Once enqueued, you have limited control over the execution order, the number of tasks running in parallel, etc, because all that is managed by the platform. If you want more control over the queue, you need to add a TaskQueue.

The MemoryTaskQueue bundled with the background_downloader allows:

• pacing the rate of enqueueing tasks, based on minInterval, to avoid 'choking' the FileDownloader when adding a large number of tasks
• managing task priorities while waiting in the queue, such that higher priority tasks are enqueued before lower priority ones
• managing the total number of tasks running concurrently, by setting maxConcurrent
• managing the number of tasks that talk to the same host concurrently, by setting maxConcurrentByHost
• managing the number of tasks running that are in the same Task.group, by setting maxConcurrentByGroup

A TaskQueue conceptually sits 'in front of' the FileDownloader queue. To use it, add it to the FileDownloader and instead of enqueuing tasks with the FileDownloader, you now add tasks to the queue:

final tq = MemoryTaskQueue();
tq.maxConcurrent = 5; // no more than 5 tasks active at any one time
tq.maxConcurrentByHost = 2; // no more than two tasks talking to the same host at the same time
tq.maxConcurrentByGroup = 3; // no more than three tasks from the same group active at the same time
FileDownloader().add(tq); // 'connects' the TaskQueue to the FileDownloader
FileDownloader().updates.listen((update) { // listen to updates as per usual
  print('Received update for ${update.task.taskId}: $update')
});
for (var n = 0; n < 100; n++) {
  task = DownloadTask(url: workingUrl, metData: 'task #$n'); // define task
  tq.add(task); // add to queue. The queue makes the FileDownloader().enqueue call
}

Because it is possible that an error occurs when the taskQueue eventually actually enqueues the task with the FileDownloader, you can listen to the enqueueErrors stream for tasks that failed to enqueue.

The default TaskQueue is the MemoryTaskQueue which, as the name suggests, keeps everything in memory. This is fine for most situations, but be aware that the queue may get dropped if the OS aggressively moves the app to the background. Tasks still waiting in the queue will not be enqueued, and will therefore be lost. If you want a TaskQueue with more persistence, subclass the MemoryTaskQueue and add persistence. In addition, if your app is suspended by the OS due to resource constraints, tasks waiting in the queue will not be enqueued to the native platform and will not run in the background. TaskQueues are therefore best for situations where you expect the queue to be emptied while the app is still in the foreground.

Fix #164 for progress updates for uploads.

Android external storage

Add configuration for Android to use external storage instead of internal storage. Either your app runs in default (internal storage) mode, or in external storage. You cannot switch between internal and external, as the directory structure that - for example - BaseDirectory.applicationDocuments refers to is different in each mode. See the configuration document for important details and limitations

Use (Config.useExternalStorage, String whenToUse) with values 'never' or 'always'. Default is Config.never.

Server suggested filename

If you want the filename to be provided by the server (instead of assigning a value to filename yourself), you now have two options. The first is to create a DownloadTask that pings the server to determine the suggested filename:

final task = await DownloadTask(url: 'https://google.com')
        .withSuggestedFilename(unique: true);

The method withSuggestedFilename returns a copy of the task it is called on, with the filename field modified based on the filename suggested by the server, or the last path segment of the URL, or unchanged if neither is feasible (e.g. due to a lack of connection). If unique is true, the filename will be modified such that it does not conflict with an existing filename by adding a sequence. For example "file.txt" would become "file (1).txt". You can now also supply a taskWithFilenameBuilder to suggest the filename yourself, based on response headers.

The second approach is to set the filename field of the DownloadTask to DownloadTask.suggestedFilename, to indicate that you would like the server to suggest the name. In this case, you will receive the name via the task's status and/or progress updates, so you have to be careful not to use the original task's filename, as that will still be DownloadTask.suggestedFilename. For example:

final task = await DownloadTask(url: 'https://google.com', filename: DownloadTask.suggestedFilename);
final result = await FileDownloader().download(task);
print('Suggested filename=${result.task.filename}'); // note we don't use 'task', but 'result.task'
print('Wrong use filename=${task.filename}'); // this will print '?' as 'task' hasn't changed

Set content length if not provided by server

To provide progress updates (as a percentage of total file size) the downloader needs to know the size of the file when starting the download. Most servers provide this in the "Content-Length" header of their response. If the server does not provide the file size, yet you know the file size (e.g. because you have stored the file on the server yourself), then you can let the downloader know by providing a {'Range': 'bytes=0-999'} or a {'Known-Content-Length': '1000'} header to the task's header field. Both examples are for a content length of 1000 bytes. The downloader will assume this content length when calculating progress.

Bug fix

Partial Downloads, using a Range header, can now be properly paused on all platforms.

Add displayName field to Task that can be used to store and display a 'human readable' description of the task. It can be displayed in a notification using {displayName}.

Bug fix for regression in compiling for Web platform (through stubbing - no actual web functionality).

Add ParallelDownloadTask. Some servers may offer an option to download part of the same file from multiple URLs or have multiple parallel downloads of part of a large file using a single URL. This can speed up the download of large files. To do this, create a ParallelDownloadTask instead of a regular DownloadTask and specify chunks (the number of pieces you want to break the file into, i.e. the number of downloads that will happen in parallel) and urls (as a list of URLs, or just one). For example, if you specify 4 chunks and 2 URLs, then the download will be broken into 8 pieces, four each for each URL.

Note that the implementation of this feature creates a regular DownloadTask for each chunk, with the group name 'chunk' which is now a reserved group. You will not get updates for this group, but you will get normal updates (status and/or progress) for the ParallelDownloadTask.

Enable compile for Web platform (through stubbing - no actual web functionality).

Automatically dismiss "complete" and "error" notifications when the user taps on the notification.

Bug fix for validating URLs to allow localhost URLs.

Update to Android Gradle Plugin 8.1.0

Add configuration Config.useCacheDir for Android and improved temp file logic. By default (Config.whenAble) the downloader will now use the application's cacheDir when the size of the file to download is less than half of the cacheQuotaBytes given to the app by Android, and use filesDir otherwise. If you find that downloads do not complete (or cannot be resumed when paused) this indicates the OS is removing the temp file from the cacheDir due to low memory conditions. In that situation, consider using Config.never to force the use of filesDir, but make sure to clean up remnant temp files in filesDir, as the OS does not do that for you.

Fix for Android 33 related to the new predictive back gesture navigation

Documentation updates

Failed download tasks can now be resumed (under certain conditions) even if the Task.allowPause field is false. Resuming a failed task will attempt to continue the download where the failure occurred. If retries are set to a value >0 then retries will also first attempt to resume, and only start from scratch if that fails.

Tasks can only resume if the ETag header provided by the server is strong, and equal to the ETag at the moment the download was paused/failed, or if it is not provided at all.

Configuration

Add configuration of the downloader for several aspects:

• Running tasks in 'foreground mode' on Android to allow longer runs and prevent the OS killing some tasks when the app is in the background
• Setting the request timeout value and, for iOS only, the 'resourceTimeout'
• Checking available space before attempting a download
• Setting a proxy
• Localizing the notification button texts on iOS
• Bypassing TLS Certificate validation (for debug mode only)

Please read the configuration document for details on how to configure.

Configuration is experimental, so please test thoroughly before using in production, and let me know if there are any issues.

Network speed and time remaining in TaskStatusUpdate

TaskStatusUpdate now has fields networkSpeed (in MB/s) and timeRemaining. Check the associated hasNetworkSpeed and hasTimeRemaining before using the values in these fields. Use networkSpeedAsString and timeRemainingAsString for human readable versions of these values.

Filter TaskRecord entries by status: allRecordsWithStatus

The database now has method allRecordsWithStatus to filter records based on their TaskStatus

Bug fix for taskNotificationTapCallback: convenience methods that await a result, such as download (but not enqueue), now use the default taskNotificationTapCallback, even though those tasks are in the awaitGroup, because that behavior is more in line with expectations. If you need a separate callback for the awaitGroup, then set it after setting the default callback. You set the default callback by omitting the group parameter in the registerCallbacks call.

Added field responseBody to TaskStatusUpdate that, if not null, contains the server response for uploads, and for downloads that are not complete (e.g. .notFound). In those instances, the server response may contain useful information (e.g. a url where the uploaded file can be found, or the reason for the 'not found' status as provided by the server)

Improved handling of notification tap callbacks.

Bug fix for Flutter Downloader migration on iOS, issue #86

Uploading multiple files in a single request

If you need to upload multiple files in a single request, create a MultiUploadTask instead of an UploadTask. It has similar parameters as the UploadTask, except you specify a list of files to upload as the files argument of the constructor, and do not use fileName, fileField and mimeType. Each element in the files list is either:

• a filename (e.g. "file1.txt"). The fileField for that file will be set to the base name (i.e. "file1" for "file1.txt") and the mime type will be derived from the extension (i.e. "text/plain" for "file1.txt")
• a record containing (fileField, filename), e.g. ("document", "file1.txt"). The fileField for that file will be set to "document" and the mime type derived from the file extension (i.e. "text/plain" for "file1.txt")
• a record containing (filefield, filename, mimeType), e.g. ("document", "file1.txt", "text/plain")

The baseDirectory and directory fields of the MultiUploadTask determine the expected location of the file referenced, unless the filename used in any of the 3 formats above is an absolute path (e.g. "/data/user/0/com.my_app/file1.txt"). In that case, the absolute path is used and the baseDirectory and directory fields are ignored for that element of the list. Once the MultiUpoadTask is created, the fields fileFields, filenames and mimeTypes will contain the parsed items, and the fields fileField, filename and mimeType contain those lists encoded as a JSON string.

Use the MultiTaskUpload object in the upload and enqueue methods as you would a regular UploadTask.

Flutter Downloader migration

Bug fixes related to migration from Flutter Downloader (see version 7.6.0). The migration is still experimental, so please test thoroughly before relying on the migration in your app.

Bug fixes

Fixed a bug on iOS related to NSNull Json decoding

Added SqlitePersistentStorage as an alternative backing storage for the downloader, and implemented migration of a pre-existing database from the Flutter Downloader package. We use the sqflite package, so this is only supported iOS and Android.

To use the downloader with SQLite backing and migration from Flutter Downloader, initialize the FileDownloader at the very beginning of your app:

final sqlStorage = SqlitePersistentStorage(migrationOptions: ['flutter_downloader', 'local_store']);
FileDownloader(persistentStorage: sqlStorage);
// start using the FileDownloader

This will migrate from either Flutter Downloader or the default LocalStore.

Added an optional parameter to the tasksFinished method that allows you to use it the moment you receive a status update for a task, like this:

void downloadStatusCallback(TaskStatusUpdate update) async {
    // process your status update, then check if all tasks are finished
    final bool allTasksFinished = update.status.isFinalState && 
        await FileDownloader().tasksFinished(ignoreTaskId: update.task.taskId) ;
    print('All tasks finished: $allTasksFinished');
  }

This excludes the task that is currently finishing up from the test. Without this, it's possible tasksFinished returns false as that currently finishing task may not have left the queue yet.

Added pathInSharedStorage method, which obtains the path to a file moved to shared storage.

To check if a file exists in shared storage, obtain the path to the file by calling pathInSharedStorage and, if not null, check if that file exists.

On Android 29+: If you have generated a version with an indexed name (e.g. 'myFile (1).txt'), then only the most recently stored version is available this way, even if an earlier version actually does exist. Also, only files stored by your app will be returned via this call, as you don't have access to files stored by other apps.

On iOS: To make files visible in the Files browser, do not move them to shared storage. Instead, download the file to the BaseDirectory.applicationDocuments and add the following to your Info.plist:

<key>LSSupportsOpeningDocumentsInPlace</key>
<true/>
<key>UIFileSharingEnabled</key>
<true/>

This will make all files in your app's Documents directory visible to the Files browser.

Bug fixes:

• Fixed bug when download is interrupted due to lost network connection (on Android)
• Fixed bug with moveToSharedStorage on iOS: shared storage is now 'faked' on iOS, creating subdirectories of the regular Documents directory, as iOS apps do not have access to shared media and download directories
• Fixed bug with notifications disappearing on iOS

Bug fix for type cast errors and for thread safety on iOS for notifications

Added method expectedFileSize() to DownloadTask, and added field expectedFileSize to
TaskProgressUpdate (provided to callbacks or listeners during download), and TaskRecord entries in the database. Note that this field is only valid when 0 < progress < 1. It is -1 if file size cannot be determined.

Improved DownloadProgressIndicator widget:

• In collapsed state, now shows progress as 'n' files finished out of 'total' started (and progress as that fraction)
• Option to force collapsed state always by setting maxExpandable to 0. When set to 1, the indicator collapses only when the second download starts. When set greater than 1, the indicator expands to show multiple simultaneous downloads.

Added usage examples upfront in the readme

Added DownloadProgressIndicator widget and modified the example app to show how to wire it up.

The widget is configurable (e.g. pause and cancel buttons) and can show multiple downloads simultaneously in either an expanded or collapsed mode.

If tracking downloads in persistent storage, pausing a file now does not override the stored progress with progressPaused.

Fixed bugs.

Added option to use a different persistent storage solution than the one provided by default. The downloader stores a few things in persistent storage, and uses a modified version of the localstore package by default. To use a different persistent storage solution, create a class that implements the PersistentStorage interface, and initialize the downloader by calling FileDownloader(persistentStorage: yourStorageClass()) as the first use of the FileDownloader.

A simple example is included in the example app (using the sqflite package).

Fixed a few bugs.

Added tasksFinished method that returns true if all tasks in the group have finished

Fixed bug related to allTasks method

Added namespace to Android build.gradle and removed irrelevant log messages

Fixed permission bug on Android 10

Changed class modifiers to allow mocking with Mockito

Migrating the persistent data from the documents directory to the support directory, so it is no longer visible in - for example - the iOS Files app, or the Linux home directory.

Further Dart 3 changes (not visible to user).

Migration to Dart 3 - not other functional change or API change. If you use Dart 2 please use version 6.1.1 of this plugin, which will be maintained until the end of 2023.

Most classes in the package are now final classes, and under the hood we use the new Records and Pattern matching features of Dart 3. None of this should matter if you've used the package as intended.

Fixed a bug on iOS related to NSNull Json decoding

Added an optional parameter to the tasksFinished method that allows you to use it the moment you receive a status update for a task, like this:

void downloadStatusCallback(TaskStatusUpdate update) async {
    // process your status update, then check if all tasks are finished
    final bool allTasksFinished = update.status.isFinalState && 
        await FileDownloader().tasksFinished(ignoreTaskId: update.task.taskId) ;
    print('All tasks finished: $allTasksFinished');
  }

This excludes the task that is currently finishing up from the test. Without this, it's possible tasksFinished returns false as that currently finishing task may not have left the queue yet.

Added pathInSharedStorage method, which obtains the path to a file moved to shared storage.

To check if a file exists in shared storage, obtain the path to the file by calling pathInSharedStorage and, if not null, check if that file exists.

On Android 29+: If you have generated a version with an indexed name (e.g. 'myFile (1).txt'), then only the most recently stored version is available this way, even if an earlier version actually does exist. Also, only files stored by your app will be returned via this call, as you don't have access to files stored by other apps.

On iOS: To make files visible in the Files browser, do not move them to shared storage. Instead, download the file to the BaseDirectory.applicationDocuments and add the following to your Info.plist:

<key>LSSupportsOpeningDocumentsInPlace</key>
<true/>
<key>UIFileSharingEnabled</key>
<true/>

This will make all files in your app's Documents directory visible to the Files browser.

Bug fixes:

• Fixed bug when download is interrupted due to lost network connection (on Android)
• Fixed bug with moveToSharedStorage on iOS: shared storage is now 'faked' on iOS, creating subdirectories of the regular Documents directory, as iOS apps do not have access to shared media and download directories
• Fixed bug with notifications disappearing on iOS

Bug fix for type cast errors and for thread safety on iOS for notifications

Added tasksFinished method that returns true if all tasks in the group have finished

Fixed bug related to allTasks method

Fixed permission bug on Android 10

Added namespace to Android build.gradle and removed irrelevant log messages

Migrating the persistent data from the documents directory to the support directory, so it is no longer visible in - for example - the iOS Files app, or the Linux home directory.

Bug fix for request method where the httpRequestMethod override was not taken into account properly.

Added unregisterCallBacks to remove callbacks if you no longer want updates, and resetUpdates to reset the updates stream so it can be listened to again.

Bug fix for DownloadTask.withSuggestedFilename for servers that do not follow case convention for the Content-Disposition header.

Breaking changes:

• The TaskStatusCallback and TaskProgressCallback now take a single argument (TaskStatusUpdate and TaskProgressUpdate respectively) instead of multiple arguments. This aligns the callback API with the updates listener API, and makes it easier to add data to an update in the future. For example, in this version we add an exception property to programmatically handle exceptions
• Similarly, the download and upload methods now return a TaskStatusUpdate instead of a TaskStatus
• For consistency, the taskStatus property of the TaskRecord (used to store task information in a persistent database) is renamed to status
• The trackTasks method no longer takes a group argument, and starts tracking for all tasks, regardless of group. If you need tracking only for a specific group, call the new trackTasksInGroup method

Other changes (non-breaking):

• You can override the httpRequestMethod used for requests by setting it in the Request, DownloadTask or UploadTask. By default, requests and downloads use GET (unless post is set) and uploads use POST
• The download, upload, downloadBatch and uploadBatch methods now take an optional onElapsedTime callback that is called at regular intervals (defined by the optional elapsedTimeInterval which defaults to 5 seconds) with the time elapsed since the call was made. This can be used to trigger UI warnings (e.g. 'this is taking rather long') or to cancel the task if it does not complete within a desired time. For performance reasons the elapsedTimeInterval should not be set to a value less than one second, and this mechanism should not be used to indicate progress.
• If a task fails, the TaskStatusUpdate will contain a TaskException that provides information about the type of exception (e.g. a TaskFileSystemException indicates an issue with storing or retrieving the file) and contains a description and (for TaskHttpException only) the httpResponseCode. If tasks are tracked, the The following TaskException subtypes may occur:
  • TaskException (general exception)
  • TaskFileSystemException (issue retrieving or storing the file)
  • TaskUrlException (issue with the url)
  • TaskConnectionException (issue with the connection to the server)
  • TaskResumeException (issue with pausing or resuming a task)
  • TaskHttpException (issue with the HTTP connection, e.g. we received an error response from the server, captured in httpResponseCode)

Fixed a few bugs.

Adds handler for when the user taps a notification, and an openFile method to open a file using the platform-specific convention.

To handle notification taps, register a callback that takes Task and NotificationType as parameters:

FileDownloader().registerCallbacks(
            taskNotificationTapCallback: myNotificationTapCallback);
            
void myNotificationTapCallback(Task task, NotificationType notificationType) {
    print('Tapped notification $notificationType for taskId ${task.taskId}');
  }

To open a file, call FileDownloader().openFile and supply either a Task or a full filePath (but not both) and optionally a mimeType to assist the Platform in choosing the right application to use to open the file. The file opening behavior is platform dependent, and while you should check the return value of the call to openFile, error checking is not fully consistent.

Note that on Android, files stored in the BaseDirectory.applicationDocuments cannot be opened. You need to download to a different base directory (e.g. .applicationSupport) or move the file to shared storage before attempting to open it.

If all you want to do on notification tap is to open the file, you can simplify the process by adding tapOpensFile: true to your call to configureNotifications, and you don't need to register a taskNotificationTapCallback.

Adds withSuggestedFilename for DownloadTask. Use:

   final task = await DownloadTask(url: 'https://google.com')
       .withSuggestedFilename(unique: true);

The method withSuggestedFilename returns a copy of the task it is called on, with the filename field modified based on the filename suggested by the server, or the last path segment of the URL, or unchanged if neither is feasible. If unique is true, the filename will be modified such that it does not conflict with an existing filename by adding a sequence. For example "file.txt" would become "file (1).txt".

Bug fixes:

• Fix for issue #35 for pausing convenience download and a specific issue with nginx related to pause/resume
• Fix for issue #38 related to notification permissions on iOS

Fix issue #34 with moveToSharedStorage on iOS

An invalid url in the Task now results in false being returned from the enqueue call on all platforms. Previously, the behavior was inconsistent.

Added optional properties to UploadTask related to multi-part uploads:

• fileField is the field name used to indicate the file (default to "file")
• mimeType overrides the mimeType derived from the filename extension
• fields is a Map<String, String> containing form field name/value pairs that will be uploaded along with the file in a multi-part upload

Added optional mimeType parameter for calls to moveToSharedStorage and moveFileToSharedStorage. This sets the mimeType directly, instead of relying on the system to determine the mime type based on the file extension. Note that this may change the filename - for example, when moving the test file google.html to SharedStorage.images while setting mimeType to 'images/jpeg', the path to the file in shared storage becomes /storage/emulated/0/Pictures/google.html.jpg (note the added .jpg).

Better permissions management, implementation of moveToSharedStorage for Android versions below Q

Minor fixes

Shared and scoped storage

The download directories specified in the BaseDirectory enum are all local to the app. To make downloaded files available to the user outside of the app, or to other apps, they need to be moved to shared or scoped storage, and this is platform dependent behavior. For example, to move the downloaded file associated with a DownloadTask to a shared 'Downloads' storage destination, execute the following after the download has completed:

    final newFilepath = await FileDownloader().moveToSharedStorage(task, SharedStorage.downloads);
    if (newFilePath == null) {
        ... // handle error
    } else {
        ... // do something with the newFilePath
    }

Because the behavior is very platform-specific, not all SharedStorage destinations have the same result. The options are:

• .downloads - implemented on all platforms, but on iOS files in this directory are not accessible to other users
• .images - implemented on Android and iOS only. On iOS files in this directory are not accessible to other users
• .video - implemented on Android and iOS only. On iOS files in this directory are not accessible to other users
• .audio - implemented on Android and iOS only. On iOS files in this directory are not accessible to other users
• .files - implemented on Android only
• .external - implemented on Android only

On MacOS, for the .downloads to work you need to enable App Sandbox entitlements and set the key com.apple.security.files.downloads.read-write to true. On Android, depending on what SharedStorage destination you move a file to, and depending on the OS version your app runs on, you may require extra permissions WRITE_EXTERNAL_STORAGE and/or READ_EXTERNAL_STORAGE . See here for details on the new scoped storage rules starting with Android API version 30, which is what the plugin is using.

Methods moveToSharedStorage and the similar moveFileToSharedStorage also take an optional directory argument for a subdirectory in the SharedStorage destination.

Thanks to @rebaz94 for implementing scoped storage on Android.

Library base directory

The BaseDirectory enum now also supports .applicationLibrary. On iOS and MacOS this is the directory provided by the path_provider package's getLibraryDirectory() call. On Other platforms, for consistency, this is the subdirectory 'Library' of the directory returned byn the getApplicationSupportDirectory() call.

Bug fix

Fixed a bug with iOS cancellation in non-US locales.

Notifications

On iOS and Android, for downloads only, the downloader can generate notifications to keep the user informed of progress also when the app is in the background, and allow pause/resume and cancellation of an ongoing download from those notifications.

Configure notifications by calling FileDownloader().configureNotification and supply a TaskNotification object for different states. For example, the following configures notifications to show only when actively running (i.e. download in progress), disappearing when the download completes or ends with an error. It will also show a progress bar and a 'cancel' button, and will substitute {filename} with the actual filename of the file being downloaded.

    FileDownloader().configureNotification(
        running: TaskNotification('Downloading', 'file: {filename}'),
        progressBar: true)

To also show a notifications for other states, add a TaskNotification for complete, error and/or paused. If paused is configured and the task can be paused, a 'Pause' button will show for the running notification, next to the 'Cancel' button.

There are three possible substitutions of the text in the title or body of a TaskNotification:

• {filename} is replaced with the filename as defined in the Task
• {progress} is substituted by a progress percentage, or '--%' if progress is unknown
• {metadata} is substituted by the Task.metaData field

Notifications on iOS follow Apple's guidelines, notably:

• No progress bar is shown, and the {progress} substitution always substitutes to an empty string. In other words: only a single running notification is shown and it is not updated until the download state changes
• When the app is in the foreground, on iOS 14 and above the notification will not be shown but will appear in the NotificationCenter. On older iOS versions the notification will be shown also in the foreground. Apple suggests showing progress and download controls within the app when it is in the foreground

While notifications are possible on desktop platforms, there is no true background mode, and progress updates and indicators can be shown within the app. Notifications are therefore ignored on desktop platforms.

The configureNotification call configures notification behavior for all download tasks. You can specify a separate configuration for a group of tasks by calling configureNotificationForGroup and for a single task by calling configureNotificationForTask. A Task configuration overrides a group configuration, which overrides the default configuration.

When attempting to show its first notification, the downloader will ask the user for permission to show notifications (platform version dependent) and abide by the user choice. For Android, starting with API 33, you need to add <uses-permission android:name="android.permission.POST_NOTIFICATIONS" /> to your app's AndroidManifest.xml. Also on Android you can localize the button text by overriding string resources bg_downloader_cancel, bg_downloader_pause, bg_downloader_resume and descriptions bg_downloader_notification_channel_name, bg_downloader_notification_channel_description. Localization on iOS is not currently supported.

Better persistence for tasks that execute while the app is suspended by the operating system.
To ensure your callbacks or listener capture events that may have happened when your app was suspended in the background, call FileDownloader().resumeFromBackground() right after registering your callbacks or listener.

Previously, Android file downloads were limited to 8 minutes. Now, long downloads are possible provided the DownloadTask.allowPause field is set to true. Just before the download times out, the downloader will pause and then resume the task in a new worker, effectively resetting the 9 minute clock. As a result, the download will eventually complete

Pause and resume

To pause or resume a task, call:

• pause to attempt to pause a task. Whether a task can be canceled or not depends primarily on the server. Soon after the task is running (TaskStatus.running) you can call taskCanResume which will return a Future that resolves to true if the server appears capable of pause & resume. If that returns false, then calling pause will return false as well, and the call is ignored
• resume to resume a previously paused task, which returns true if resume appears feasible. The taskStatus will follow the same sequence as a newly enqueued task. If resuming turns out to be not feasible (e.g. the operating system deleted the temp file with the partial download) then the task will either restart as a normal download, or fail.

This adds TaskStatus.paused which may require updating switch statements to remain exhaustive, though this status will never appear unless you use pause.

Individual status and progress callbacks for batch upload and download

Adds status and progress callbacks for individual files in a batch. This is breaking if you used a batch progress callback earlier, as that is now a named parameter. Change:

   final result = await FileDownloader().downloadBatch(tasks, (succeeded, failed) {
      print('$succeeded files succeeded, $failed have failed');
      print('Progress is ${(succeeded + failed) / tasks.length} %');
   });

to

   final result = await FileDownloader().downloadBatch(tasks, batchProgressCallback: (succeeded, failed) {
    ...
   });

To also monitor status and progress for each file in the batch, add a taskStatusCallback (taking Task and TaskStatus as arguments) and/or a taskProgressCallback (taking Task` and a double as arguments).

iOS minimum version from 11.0 to 13.0

To improve Swift code readability and maintenance, the minimum iOS version has moved from 11.0 to 13.0

Fixed another bug with database.allRecords if taskId contains illegal filename characters (like '/'). For tracking record id purposes those are now replaced with '_'

Fixed bug with database.allRecords if taskId contains illegal filename characters (like '/'). For tracking record id purposes those are now replaced with '_'

Upgraded dependency to address issue with Windows platform database performance

Added creationTime field to Request and Task.

Added allRecordsOlderThan(Duration age, {String? group}) to database, making it easy to extract the TaskRecord entries that are stale.

Adds optional tracking of task status and progress in a persistent database.

To keep track of the status and progress of all tasks, even after they have completed, activate tracking by calling trackTasks() and use the database field to query. For example:

    // at app startup, start tracking
    await FileDownloader().trackTasks();
    
    
    // somewhere else: enqueue a download
    final task = DownloadTask(
            url: 'https://google.com',
            filename: 'testfile.txt');
    final successfullyEnqueued = await FileDownloader().enqueue(task);
    
    // somewhere else: query the task status by getting a `TaskRecord`
    // from the database
    final record = await FileDownloader().database.recordForId(task.taskId);
    print('Taskid ${record.taskId} with task ${record.task} has '
        'status ${record.taskStatus} and progress ${record.progress}'

You can interact with the database using allRecords, recordForId, deleteAllRecords, deleteRecordWithId etc. Note that only tasks that you asked to be tracked (using trackTasks, which activates tracking for all tasks in a group) will be in the database. All active tasks in the queue, regardless of tracking, can be queried via the FileDownloader.taskForId call etc, but those will only return the task itself, not its status or progress, as those are expected to be monitored via listener or callback. Note: tasks that are started using download, upload, batchDownload or batchUpload are assigned a special group name 'await', as callbacks for these tasks are handled within the FileDownloader. If you want to track those tasks in the database, call FileDownloader().trackTasks(FileDownloader.awaitGroup) at the start of your app.