Xamarin.Forms - File Browser

Delpin Susai Raj

6y25.3k5100Article

Xamarin.FormsFilePickerFIleBrowser

5 Comments

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gadda raju4y ago
{Java.Lang.NullPointerException: uri at Java.Interop.JniEnvironment+InstanceMethods.CallNonvirtualObjectMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniObjectReference type, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x0008e] in <bd6bd528a8784b7caf03e9f25c9f0d7b>:0 at Java.Interop.JniPeerMembers+JniInstanceMethods.InvokeNonvirtualObjectMethod (System.String encodedMember, Java.Interop.IJavaPeerable self, Java.Interop.JniArgumentValue* parameters) [0x0001f] in <bd6bd528a8784b7caf03e9f25c9f0d7b>:0 at Android.Content.ContentResolver.Query (Android.Net.Uri uri, System.String[] projection, System.String selection, System.String[] selectionArgs, System.String sortOrder) [0x000a0] in /Users/builder/azdo/_work/1/s/xamarin-android/src/Mono.Android/obj/Release/monoandroid10/android-28/mcw/Android.Content.ContentResolver.cs:1098 at Plugin.FilePicker.IOUtil.GetDataColumn (Android.Content.Context context, Android.Net.Uri uri, System.String selection, System.String[] selectionArgs) [0x00013] in D:\a\1\s\src\Plugin.FilePicker\Android\IOUtil.android.cs:154 at Plugin.FilePicker.IOUtil.GetPath (Android.Content.Context context, Android.Net.Uri uri) [0x0017d] in D:\a\1\s\src\Plugin.FilePicker\Android\IOUtil.android.cs:111 at Plugin.FilePicker.FilePickerActivity.OnActivityResult (System.Int32 requestCode, Android.App.Result resultCode, Android.Content.Intent data) [0x00054] in D:\a\1\s\src\Plugin.FilePicker\Android\FilePickerActivity.android.cs:168 --- End of stack trace from previous location where exception was thrown --- at Plugin.FilePicker.FilePickerImplementation.PickFile (System.String[] allowedTypes) [0x00028] in D:\a\1\s\src\Plugin.FilePicker\Android\FilePickerImplementation.android.cs:60 at FileUploadPOC.MainPage.PickAndShow (System.String[] fileTypes) [0x0002e] in C:\Users\Gadda.Raju\Downloads\XamarinForms-FilePicker-master\FileUploadPOC\MainPage.xaml.cs:47 --- End of managed Java.Lang.NullPointerException stack trace --- java.lang.NullPointerException: uri at java.util.Objects.requireNonNull(Objects.java:245) at android.content.ContentResolver.query(ContentResolver.java:1166) at android.content.ContentResolver.query(ContentResolver.java:1124) at android.content.ContentResolver.query(ContentResolver.java:1080) at crc64424a8adc5a1fbe28.FilePickerActivity.n_onActivityResult(Native Method) at crc64424a8adc5a1fbe28.FilePickerActivity.onActivityResult(FilePickerActivity.java:47) at android.app.Activity.dispatchActivityResult(Activity.java:8469) at android.app.ActivityThread.deliverResults(ActivityThread.java:5364) at android.app.ActivityThread.handleSendResult(ActivityThread.java:5412) at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2317) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:255) at android.app.ActivityThread.main(ActivityThread.java:8192) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:632) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1049) }
gadda raju4y ago
Thank you very much for this article.When I attach pdf and doc files using Recent files I'm getting the following exception. Could you please help on this.
Daniel Sarmiento5y ago
Hello man, Sorry but I have a Question, Is there a way to choose multiple files based on this?
Daniel Sarmiento5y ago
Thank you very much for the article, it was the only one that worked for me on the whole internet
- Delpin Susai Raj5y ago
  Thank you.

Introduction

Xamarin.Forms code runs on multiple platforms - each of which has its own filesystem. This means that reading and writing files is most easily done using the native file APIs on each platform. Alternatively, embedded resources are a simpler solution to distribute data files with an app.

Prerequisites

Visual Studio 2017 or later (Windows or Mac)

Setting up a Xamarin.Forms Project

Start by creating a new Xamarin.Forms project. You wíll learn more by going through the steps yourself.

Create a new or existing Xamarin forms(.Net standard) Project with Android and iOS Platform.

Nuget

Install the following Nuget from Nuget Manager In your Visual Studio.

Name	Xamarin.Plugin.FilePicker
Version	2.1.41
Url	https://www.nuget.org/packages/Xamarin.Plugin.FilePicker/

Xamarin.Essentials

Xamarin.Essentials also supports File Picker but it's in Preview. Once the FilePicker is moved to stable you can update Xamarin.Pulgin.FilePicker to Xamarin.Essentials from here.

Setup UI

Now, I created a simple UI for file browser.

MainPage.xaml

<?xml version="1.0" encoding="utf-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:d="http://xamarin.com/schemas/2014/forms/design" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="FileUploadPOC.MainPage">
<StackLayout HorizontalOptions="Center">
<Image Source="xamarinmonkeysbanner.png" HorizontalOptions="Center" Margin="0,100,0,0"/>
<Button Margin="0,20,0,0" Text="Browse File" Clicked="Button_Clicked"></Button>
<Label x:Name="lblName"/>
<Label x:Name="lblFilePath"/>
</StackLayout>
</ContentPage>

File Browser

Below code is for file picker. Here we will get two values, FileName and FilePath.

private async Task PickAndShow(string[] fileTypes)
{
try
{
var pickedFile = await CrossFilePicker.Current.PickFile(fileTypes);
if (pickedFile != null)
{
lblName.Text = pickedFile.FileName;
lblFilePath.Text = pickedFile.FilePath;
}
}
catch (Exception ex)
{
}
}

File Types

Note, you can define the file types for platform specific.

if (Device.RuntimePlatform == Device.Android)
{
fileTypes = new string[] { "image/png", "image/jpeg" };
}
if (Device.RuntimePlatform == Device.iOS)
{
fileTypes = new string[] { "public.image" }; // same as iOS constant UTType.Image
}
if (Device.RuntimePlatform == Device.UWP)
{
fileTypes = new string[] { ".jpg", ".png" };
}
if (Device.RuntimePlatform == Device.WPF)
{
fileTypes = new string[] { "JPEG files (*.jpg)|*.jpg", "PNG files (*.png)|*.png" };
}

Reference for other file types,

https://stackoverflow.com/questions/41797644/xamarin-ios-filtering-out-the-filetype-show-on-document-picker

MainPage.Xaml.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Plugin.FilePicker;
using Xamarin.Essentials;
using System.Security.Cryptography.X509Certificates;
namespace FileUploadPOC
{
// Learn more about making custom code visible in the Xamarin.Forms previewer
// by visiting https://aka.ms/xamarinforms-previewer
[DesignTimeVisible(false)]
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
}
async void Button_Clicked(System.Object sender, System.EventArgs e)
{
try
{
string[] fileTypes = null;
if (Device.RuntimePlatform == Device.iOS)
{
fileTypes = new string[] {"com.adobe.pdf", "public.rft", "com.microsoft.word.doc", "org.openxmlformats.wordprocessingml.document" }; }
await PickAndShow(fileTypes);
}
catch (Exception ex)
{
}
}
private async Task PickAndShow(string[] fileTypes)
{
try
{
var pickedFile = await CrossFilePicker.Current.PickFile(fileTypes);
if (pickedFile != null)
{
lblName.Text = pickedFile.FileName;
lblFilePath.Text = pickedFile.FilePath;
}
}
catch (Exception ex)
{
}
}
}
}

Debug your App

Download source code here.

I hope you have understood how to browse files in your device and drive in Xamarin.Forms.

Thanks for reading. Please share your comments and feedback. Happy Coding :)