How can I select and upload Multiple images in Flutter

Question

I tried to find how to select and upload multiple images in flutter but most of the plugins are not working or I did not understand them well. I found little application but it selects and upload only one picture. How to change this code that user can select and upload multiple pictures or is there any other alternatives. Please write in details, i am freshman in coding. Thanks in advance.

import 'package:flutter/material.dart';
import 'dart:io';
import 'package:http/http.dart' as http;
import 'package:image_picker/image_picker.dart';
import 'package:mime/mime.dart';
import 'dart:convert';
import 'package:http_parser/http_parser.dart';
import 'package:toast/toast.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Image Upload Demo',
        theme: ThemeData(primarySwatch: Colors.pink),
        home: ImageInput());
  }
}

class ImageInput extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _ImageInput();
  }
}

class _ImageInput extends State<ImageInput> {
  // To store the file provided by the image_picker
  File _imageFile;

  // To track the file uploading state
  bool _isUploading = false;

  String baseUrl = 'http://YOUR_IPV4_ADDRESS/flutterdemoapi/api.php';

  void _getImage(BuildContext context, ImageSource source) async {
    File image = await ImagePicker.pickImage(source: source);

    setState(() {
      _imageFile = image;
    });

    // Closes the bottom sheet
    Navigator.pop(context);
  }

  Future<Map<String, dynamic>> _uploadImage(File image) async {
    setState(() {
      _isUploading = true;
    });

    // Find the mime type of the selected file by looking at the header bytes of the file
    final mimeTypeData =
        lookupMimeType(image.path, headerBytes: [0xFF, 0xD8]).split('/');

    // Intilize the multipart request
    final imageUploadRequest =
        http.MultipartRequest('POST', Uri.parse(baseUrl));

    // Attach the file in the request
    final file = await http.MultipartFile.fromPath('image', image.path,
        contentType: MediaType(mimeTypeData[0], mimeTypeData[1]));

    // Explicitly pass the extension of the image with request body
    // Since image_picker has some bugs due which it mixes up
    // image extension with file name like this filenamejpge
    // Which creates some problem at the server side to manage
    // or verify the file extension
    imageUploadRequest.fields['ext'] = mimeTypeData[1];

    imageUploadRequest.files.add(file);

    try {
      final streamedResponse = await imageUploadRequest.send();

      final response = await http.Response.fromStream(streamedResponse);

      if (response.statusCode != 200) {
        return null;
      }

      final Map<String, dynamic> responseData = json.decode(response.body);

      _resetState();

      return responseData;
    } catch (e) {
      print(e);
      return null;
    }
  }

  void _startUploading() async {
    final Map<String, dynamic> response = await _uploadImage(_imageFile);
    print(response);
    // Check if any error occured
    if (response == null || response.containsKey("error")) {
      Toast.show("Image Upload Failed!!!", context,
          duration: Toast.LENGTH_LONG, gravity: Toast.BOTTOM);
    } else {
      Toast.show("Image Uploaded Successfully!!!", context,
          duration: Toast.LENGTH_LONG, gravity: Toast.BOTTOM);
    }
  }

  void _resetState() {
    setState(() {
      _isUploading = false;
      _imageFile = null;
    });
  }

  void _openImagePickerModal(BuildContext context) {
    final flatButtonColor = Theme.of(context).primaryColor;
    print('Image Picker Modal Called');
    showModalBottomSheet(
        context: context,
        builder: (BuildContext context) {
          return Container(
            height: 150.0,
            padding: EdgeInsets.all(10.0),
            child: Column(
              children: <Widget>[
                Text(
                  'Pick an image',
                  style: TextStyle(fontWeight: FontWeight.bold),
                ),
                SizedBox(
                  height: 10.0,
                ),
                FlatButton(
                  textColor: flatButtonColor,
                  child: Text('Use Camera'),
                  onPressed: () {
                    _getImage(context, ImageSource.camera);
                  },
                ),
                FlatButton(
                  textColor: flatButtonColor,
                  child: Text('Use Gallery'),
                  onPressed: () {
                    _getImage(context, ImageSource.gallery);
                  },
                ),
              ],
            ),
          );
        });
  }

  Widget _buildUploadBtn() {
    Widget btnWidget = Container();

    if (_isUploading) {
      // File is being uploaded then show a progress indicator
      btnWidget = Container(
          margin: EdgeInsets.only(top: 10.0),
          child: CircularProgressIndicator());
    } else if (!_isUploading && _imageFile != null) {
      // If image is picked by the user then show a upload btn

      btnWidget = Container(
        margin: EdgeInsets.only(top: 10.0),
        child: RaisedButton(
          child: Text('Upload'),
          onPressed: () {
            _startUploading();
          },
          color: Colors.pinkAccent,
          textColor: Colors.white,
        ),
      );
    }

    return btnWidget;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Upload Demo'),
      ),
      body: Column(
        children: <Widget>[
          Padding(
            padding: const EdgeInsets.only(top: 40.0, left: 10.0, right: 10.0),
            child: OutlineButton(
              onPressed: () => _openImagePickerModal(context),
              borderSide:
                  BorderSide(color: Theme.of(context).accentColor, width: 1.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Icon(Icons.camera_alt),
                  SizedBox(
                    width: 5.0,
                  ),
                  Text('Add Image'),
                ],
              ),
            ),
          ),
          _imageFile == null
              ? Text('Please pick an image')
              : Image.file(
                  _imageFile,
                  fit: BoxFit.cover,
                  height: 300.0,
                  alignment: Alignment.topCenter,
                  width: MediaQuery.of(context).size.width,
                ),
          _buildUploadBtn(),
        ],
      ),
    );
  }
}

Answer 1

I used that package:

dependencies: multi_image_picker: ^4.6.7

Ex:

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

import 'package:multi_image_picker/multi_image_picker.dart';

void main() => runApp(new MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Asset> images = List<Asset>();
  String _error;

  @override
  void initState() {
    super.initState();
  }

  Widget buildGridView() {
    if (images != null)
      return GridView.count(
        crossAxisCount: 3,
        children: List.generate(images.length, (index) {
          Asset asset = images[index];
          return AssetThumb(
            asset: asset,
            width: 300,
            height: 300,
          );
        }),
      );
    else
      return Container(color: Colors.white);
  }

  Future<void> loadAssets() async {
    setState(() {
      images = List<Asset>();
    });

    List<Asset> resultList;
    String error;

    try {
      resultList = await MultiImagePicker.pickImages(
        maxImages: 300,
      );
    } on Exception catch (e) {
      error = e.toString();
    }

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      images = resultList;
      if (error == null) _error = 'No Error Dectected';
    });
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('Plugin example app'),
        ),
        body: Column(
          children: <Widget>[
            Center(child: Text('Error: $_error')),
            RaisedButton(
              child: Text("Pick images"),
              onPressed: loadAssets,
            ),
            Expanded(
              child: buildGridView(),
            )
          ],
        ),
      ),
    );
  }
}

Answer 2

Add dependecy of image_picker:

   image_picker: ^0.8.4+3

Then make a method for selectImages():

  final ImagePicker imagePicker = ImagePicker();
  List<XFile>? imageFileList = [];

  void selectImages() async {
     final List<XFile>? selectedImages = await 
            imagePicker.pickMultiImage();
       if (selectedImages!.isNotEmpty) {
          imageFileList!.addAll(selectedImages);
       }
      print("Image List Length:" + imageFileList!.length.toString());
      setState((){});
  }

Create a builder for showing selected Images:

 return Scaffold(
      appBar: AppBar(
      title: Text('Multiple Images'),
     ),
    body: SafeArea(
       child: Column(
         children: [
             ElevatedButton(
                onPressed: () {
                  selectImages();
              },
             child: Text('Select Images'),
           ),
           Expanded(
              child: Padding(
              padding: const EdgeInsets.all(8.0),
              child: GridView.builder(
                    itemCount: imageFileList!.length,
                   gridDelegate: 
                      SliverGridDelegateWithFixedCrossAxisCount(
                          crossAxisCount: 3),
                      itemBuilder: (BuildContext context, int index) {
                       return Image.file(File(imageFileList![index].path), 
                    fit: BoxFit.cover,);
                 }),
             ),
           ),
         ],
        ),
      ));

Complete Source code available in github link...

https://github.com/NishaJain24/multi_image_picker