Upload and Download files from Azure Storage

Article
09/24/2014

Here is sample code to download and upload files to Azure Storage from Universal Windows Apps.

Complete source code is available here

Introduction to Universal Windows Apps

Visual Studio template for Universal Windows Apps allows developers to build Windows Store App and Phone App in a single Visual Studio solution. This Visual Studio solution includes three projects, project for design and feature experiences unique to Store App, second project for Phone App and third project for shared code. For more details on Universal Apps template in Visual Studio please click here

Here is the Visual Studio projects for Universal Windows Apps.

The project ending with .Windows is for Store App, project ending with .WindowsPhone is for Phone App and .Shared is for shared code.

In the Shared Project, use following #defines to write specific code for Phone App or Store App

 
#if WINDOWS_PHONE_APP
    // For Windows Phone App
#elif WINDOWS_APP
    // For Windows Store App
#else
    //  Error
#endif

Introduction to Azure Storage

Azure Storage is storage in cloud which is accessible from anywhere in the world, from any type of application, whether it’s running in the cloud, on the desktop, on an on-premises server, or on a mobile or tablet device. Azure Storage support four types of storage : Blob Storage, Table Storage, Queue Storage and File Storage. For more details please click here.

Steps to create Azure Storage

Login to Azure Portal @ https://manage.windowsazure.com/
Click on New at the bottom left
Select Data Services | Storage | Quick Create and enter URL as shown below
Next create container, click on Create a Container in the Storage | UniversalAppAzureStorage | Container tab as shown below
Enter a name for container as shown below
Click on Manage Access Keys in the Dashboard tab and copy the Storage Account Name and Primary Access Key as shown

Steps to create Universal Windows App

Open Visual Studio
Click on File | New
Select Templates | Visual C# | Store Apps | Universal Apps | Hub App as shown
Now install NuGet Package for Azure Store
Right click on the .Windows project and select Manage NuGet Packages
In the search window type Azure Storage as shown below
Click on Install button for Azure Storage
Now install the Azure Storage NuGet Package on .WindowsPhone project
Right click on the .WindowsPhone project and select Manage NuGet Packages
In the search window type Azure Storage and click on the install button
Now lets right code for uploading file to Azure Storage
Open App.xaml.cs file in the .Shared Project

Copy this below upload function


       private async Task<int> UploadToAzureStorage()
        {
            try
            {
                //  create Azure Storage
                CloudStorageAccount storageAccount = CloudStorageAccount.Parse("DefaultEndpointsProtocol=https;AccountName=universalappazurestorage;AccountKey=<your key>");

                //  create a blob client.
                CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

                //  create a container 
                CloudBlobContainer container = blobClient.GetContainerReference("containerone");

                //  create a block blob
                CloudBlockBlob blockBlob = container.GetBlockBlobReference("filename");

                //  create a local file
                StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("filename", CreationCollisionOption.ReplaceExisting);

                //  copy some txt to local file
                MemoryStream ms = new MemoryStream();
                DataContractSerializer serializer = new DataContractSerializer(typeof(string));
                serializer.WriteObject(ms, "Hello Azure World!!");

                using (Stream fileStream = await file.OpenStreamForWriteAsync())
                {
                    ms.Seek(0, SeekOrigin.Begin);
                    await ms.CopyToAsync(fileStream);
                    await fileStream.FlushAsync();
                }

                //  upload to Azure Storage 
                await blockBlob.UploadFromFileAsync(file);

                return 1;
            }
            catch
            {
                //  return error
                return 0;
            }
        }

Now copy this below download function


        private async Task<int> DownloadFromAzureStorage()
        {
            try
            {
                //  create Azure Storage
                CloudStorageAccount storageAccount = CloudStorageAccount.Parse("DefaultEndpointsProtocol=https;AccountName=universalappazurestorage;AccountKey=<your key>");

                //  create a blob client.
                CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

                //  create a container 
                CloudBlobContainer container = blobClient.GetContainerReference("containerone");

                //  create a block blob
                CloudBlockBlob blockBlob = container.GetBlockBlobReference("filename");

                //  create a local file
                StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync("filename_from_azure", CreationCollisionOption.ReplaceExisting);

                //  download from Azure Storage
                await blockBlob.DownloadToFileAsync(file);

                return 1;
            }
            catch
            {
                //  return error
                return 0;
            }
        }

Now call these two functions


        protected async override void OnLaunched(LaunchActivatedEventArgs e)
        {
#if DEBUG
            if (System.Diagnostics.Debugger.IsAttached)
            {
                this.DebugSettings.EnableFrameRateCounter = true;
            }
#endif
            int r = await UploadToAzureStorage();
            if (r == 1)
            {
                await DownloadFromAzureStorage();
            }

            Frame rootFrame = Window.Current.Content as Frame;

Run the Windows Store App and check the files local storage
To get the path of the local storage, look at the Path variable value of the StorageFile as shown
here is the complete source code

Upload and Download files from Azure Storage

Introduction to Universal Windows Apps

Introduction to Azure Storage

Steps to create Azure Storage

Steps to create Universal Windows App

Additional resources