Empowering Your App with Flutter Document Picker Package

Welcome to our comprehensive coverage of Flutter's exciting feature: the document picker. Flutter, Google's open-source UI toolkit, has been a game-changer for mobile app creation. Among its many features, the ability to pick documents is critical for many modern applications, particularly those handling cloud files, local storage, user-generated content, and more.

Picking documents can range from selecting one file to choosing multiple files. It encapsulates a broad spectrum of operations, such as opening images, and PDFs, downloading Dart files from the cloud, etc. But how does the Flutter document picker package aid in this operation? Let's dive in!

About Flutter Document Picker Package

To facilitate the process of file or document selection, Flutter offers a convenient utility - the Flutter Document Picker. This package allows users to pick documents or files from their devices in a simplified manner, contributing significantly to an application's usability and smooth user interface.

When implementing document-picking operations in Flutter, you shouldn't reinvent the wheel. The Flutter Document Picker package is a well-optimized solution that integrates easily with most Flutter projects. One key purpose it serves is enabling users to upload or download files from local storage or a cloud service. Think PDFs, spreadsheets, images, and much more!

The functionality of the Flutter Document Picker is quite extensive. It can pick single or multiple files, verify extensions, filter files based on specific criteria, and more. It interacts efficiently with both the iOS UIDocumentPickerViewController and Android's Intent.ACTION_OPEN_DOCUMENT, supporting multiple platforms.

Flutter Document Picker Vs. Flutter File Picker: A Comparison

Before we delve into the nuts and bolts of the Flutter document picker, it's crucial to distinguish it from another familiar term: the Flutter file picker. While they might seem identical initially, subtle differences set them apart.

The Flutter file picker operates like the document but specializes in multimedia file selection (like images, audio, and video). Ideal for accessing files stored on the device, it offers multiple file selections and excellent extension filtering support, delivering a rich native experience.

On the other hand, the Flutter document picker focuses on a broader range of files. It can help you select files, including but not limited to Word documents, PDFs, Excel spreadsheets, and more. Like the file picker, it also offers single or multiple file selection but shines in its cross-platform compatibility and the ability to pick files filtered by specific extensions.

While both provide an interface for accessing files, choosing the right one depends on the application requirements. Combining the powers of both can sometimes lead to more comprehensive results.

Explanation: The Internal Workings of Flutter Document Picker

Let's uncover the mechanics behind the Flutter Document Picker. Initiated by a user's action to pick files, this package interacts with the device's native file explorer. It prompts the user to select file(s) based on the parameters fed into it.

When a file is picked, it's copied to the app's temporary directory. If required, the file's extension can be checked against a parameter called allowedFileExtensions, ensuring the selected file fits the desired extension. If it doesn't match, an 'extension_mismatch' error is returned.

On iOS, allowedUtiTypes filters files by list of UTI (Uniform Type Identifiers) types. The UTIs provide flexibility for working with file data in various formats, enhancing the user's ability to choose files. On Android, the plugin uses Intent.ACTION_OPEN_DOCUMENT, favoring applications with a minSdkVersion of 19 or more.

Notably, the document picker can sanitize invalid file name characters to provide compatibility with the local file system. This feature demonstrates its close integration with the platform native file explorer.

Furthermore, the FlutterDocumentPickerParams can specify a list of allowed file extensions, UTI types, MIME types, and invalid file name symbols, thus controlling the file picking operation.

How to Use Flutter Document Picker

Integrating and using Flutter Document Picker in your Flutter project is simple, provided you follow the below steps. We'll also offer a quick look at a basic code snippet to help understand its usage better.

Step 1: Add the Flutter Document Picker package dependency to your pubspec.yaml file.

Run flutter packages get command in your terminal to fetch the dependencies package.

Step 2: Import the package in your Dart file where the document picker functionality is required.

Step 3: Then, you can call the openDocument() method as shown below, which will prompt the user to select a file.

The above call will be placed inside a callback or an async function.

Step 4: For multiple file selection or filter by specific file extensions, you can provide some parameters to the openDocument() method using the FlutterDocumentPickerParams.

That's a basic overview of using Flutter Document Picker in your Flutter app to enhance document-picking functionalities. It's worth noting that the package efficiently handles permissions and provides a concise API, making your life as a developer easier.

Flutter Document Picker Example: A Step-by-step Guide

Let's solidify our understanding of the Flutter Document Picker with a comprehensive example. It will illustrate how to select files using the document picker and showcase the details such as the file name, file size, etc.

Create a new Flutter project using your preferred editor (VS Code, Android Studio, etc.). You can create a new Flutter project in VS Code using the below command in the terminal.

After successfully creating the flutter_document_picker_demo, open the pubspec.yaml file, add the flutter_document_picker dependency package, and then run flutter packages get.

Now, open the main.dart file and remove default starter code for a fresh start. We will build a simple Flutter app with a button that facilitates document picking when pressed.

Import the package and set up a stateful widget:

In this example, we have created a button, and when pressed, it invokes FlutterDocumentPicker.openDocument(). This opens the document picker, allowing the user to pick a .txt file. Upon selection, the chosen document's path is displayed on the app's screen.

Building this file picker demo should help solidify your understanding and get you started with the Flutter Document Picker.

Strategies to Pick Multiple Files with Flutter Document Picker

We've just seen how to select a single file using Flutter Document Picker, but what about when you need to select more than one file?

The Flutter Document Picker offers a convenient solution. Using the openDocuments() function, you can enable users to select multiple files simultaneously. Here is a basic example illustrating this:

In the example above, openDocuments() replaces openDocument(), highlighting Flutter's philosophy of "everything is a widget". You can extend the allowed file extensions based on your needs.

It's important to note that the paths returned are a List of Strings, representing the individual file paths of your selected files. You can use these paths to perform further operations on the selected files, such as displaying, reading, or uploading them.

Remember, picking multiple files adds another layer of complexity to your Flutter app, so it's crucial to consider user experience and handle all possible edge cases to ensure an optimal experience.

Integrating Flutter File and Document Picker with Native File Explorer

Exploring the capabilities of Flutter's document picker wouldn't be complete without discussing its integration with the native file explorer. Depending on the platform, the Flutter document picker uses Android's Intent.ACTION_OPEN_DOCUMENT or iOS's UIDocumentPickerViewController. This lends a more user-friendly and familiar interface to your Flutter app.

Users can easily navigate through their files and folders without getting lost, thanks to the native file explorer. This integration removes the need for an artificial file picker UI, providing more seamless file navigation on the platform. Filtering allowed file extensions or types ensures only relevant files are shown.

Let's add an example from our previous section, where we prompt the user to select a .txt file:

The allowed file extensions parameter lists only .txt as an acceptable file extension. Therefore, in the Android or iOS native file explorer called by the document picker, only .txt files are selectable, improving the user experience.

The seamless integration with the native file explorer offered by the Flutter document picker makes it a powerful tool in any developer's kit.

Understanding File Picker in Flutter: A Deep Dive

Now that you have a fundamental understanding of Flutter Document Picker, let's dive deeper into some of its core aspects and the available customization options. The flexibility of this tool is what makes it incredibly useful for developers, as you can tailor it to your specific needs.

1. Single or Multiple Files: As discussed earlier, you can pick one or multiple files simultaneously. The openDocument method picks a single file, while the openDocuments method allows multiple file selection.
2. Extension Filtering Support: You can restrict the type of files the user can pick by specifying the allowedFileExtensions parameter, which accepts a list of extension strings.
3. Platform Compatibility: The platform-agnostic package can interact with Android and iOS native file explorers. This enables you to use a single line of code to pick files across multiple platforms.
4. Error Handling: The package is designed to handle errors gracefully. For instance, when a user picks a file with an extension not specified in the allowedFileExtensions list, it returns an 'extension_mismatch' error.
5. File Information: The paths returned by the methods can be used to fetch more details about the picked files. You can obtain the selected file's details, such as name, size, type, and more.

Remember, as with any code you integrate into your project, be it a package or a command, always refer to the official documentation to fully understand its capabilities and limitations. The official Flutter Document Picker README provides excellent insights into its working and additional parameters that you can use.

Key Takeaways: Using Flutter Document Picker and File Picker Efficiently

Document picking is an integral component in developing many modern mobile applications. The Flutter document picker package provides a simple and user-friendly way to access the native file explorer to pick single or multiple files in your Flutter apps, enhancing the app's overall user experience.

To sum up, here are the key takeaways:

1. Flutter document picker is a powerful package that allows users to browse their device's file system and pick documents via native interfaces.
2. Flutter file picker, though similar, specializes in multimedia file selection, making it the preferred choice for image or media-centered apps.
3. Depending on your requirements, you might need to choose between single file or multiple file selections, an option the Flutter Document Picker efficiently handles.
4. The inherent capability to interface with Android's Intent.ACTION_OPEN_DOCUMENT or iOS's UIDocumentPickerViewController makes your applications run smoothly across multiple platforms.
5. Efficient extension filtering support, choosing file types, and handling users' errors and actions all ensure an optimal application experience.
6. The official Flutter document picker package readily provides complementary extensions like the ones allowing specific file type picking, file name sanitization, etc.
7. Combining Flutter Document Picker and File Picker could sometimes provide a better range of file picking functionality, exclusively in mixed-content apps.
8. Always refer to official documentation for the finer details and latest updates.

With a proper understanding of the package and its competencies, you can now significantly improve data interaction in your application, posing a smooth sailing user experience.

Conclusion

In the ever-progressing Flutter ecosystem, efficiently picking files and documents is a crucial requirement for many applications. Leveraging the power of the Flutter Document Picker, developers can build rich, user-friendly apps that provide an intuitive interface for file selection. It's not just about picking files; it's about enhancing user interactions, extending app capabilities, and creating better software. Happy Fluttering!

dependencies:
    flutter_document_picker: ^version

import 'package:flutter_document_picker/flutter_document_picker.dart';

final path = await FlutterDocumentPicker.openDocument();

FlutterDocumentPickerParams params = FlutterDocumentPickerParams(
    allowedFileExtensions: ['txt', 'doc', 'docx', 'pdf'],
    allowedMimeTypes: ['application/*'],
    invalidFileNameSymbols: ['/'],
);
final path = await FlutterDocumentPicker.openDocument(params: params);

flutter create flutter_document_picker_demo

import 'package:flutter/material.dart';
import 'package:flutter_document_picker/flutter_document_picker.dart';

void main() {
 runApp(const MyApp());
}

class MyApp extends StatelessWidget {
 const MyApp({Key? key}) : super(key: key);
 @override
 Widget build(BuildContext context) {
   return MaterialApp(
     home: FlutterDocumentPickerDemo(),
   );
 }
}

class FlutterDocumentPickerDemo extends StatefulWidget {
 @override
 _FlutterDocumentPickerDemoState createState() =>
     _FlutterDocumentPickerDemoState();
}

class _FlutterDocumentPickerDemoState extends State<FlutterDocumentPickerDemo> {
 String _pickedFilePath = '';

 Future<void> pickDocument() async {
   final path = await FlutterDocumentPicker.openDocument(
       params: FlutterDocumentPickerParams(
           allowedFileExtensions: ['txt'],
           invalidFileNameSymbols: ['/']));
   if (path != null) {
     setState(() {
       _pickedFilePath = path;
     });
   }
 }

 @override
 Widget build(BuildContext context) {
   return Scaffold(
     body: Center(
       child: Column(
         mainAxisAlignment: MainAxisAlignment.center,
         children: <Widget>[
           Text(
             'Picked File Path:',
             style: TextStyle(fontWeight: FontWeight.bold),
           ),
           SizedBox(height: 10),
           Text(_pickedFilePath),
           SizedBox(height: 50),
           ElevatedButton(
             onPressed: pickDocument,
             child: Text('Pick Document'),
           ),
         ],
       ),
     ),
   );
 }
}

FlutterDocumentPickerParams params = FlutterDocumentPickerParams(
    allowedFileExtensions: ['txt', 'doc', 'docx', 'pdf'],
);

final paths = await FlutterDocumentPicker.openDocuments(params: params);

FlutterDocumentPickerParams params = FlutterDocumentPickerParams(
    allowedFileExtensions: ['txt'],
    invalidFileNameSymbols: ['/'],
);

final path = await FlutterDocumentPicker.openDocument(params: params);