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Quickstart: Azure Blob Storage library v12 - .NET
In this quickstart, you will learn how to use the Azure Blob Storage client library version 12 for .NET to create a container and a blob in Blob (object) storage. Next, you learn how to download the blob to your local computer, and how to list all of the blobs in a container.
twooley
twooley
03/03/2021
storage
blobs
quickstart
devx-track-csharp

Quickstart: Azure Blob Storage client library v12 for .NET

Get started with the Azure Blob Storage client library v12 for .NET. Azure Blob Storage is Microsoft's object storage solution for the cloud. Follow steps to install the package and try out example code for basic tasks. Blob storage is optimized for storing massive amounts of unstructured data.

Use the Azure Blob Storage client library v12 for .NET to:

  • Create a container
  • Upload a blob to Azure Storage
  • List all of the blobs in a container
  • Download the blob to your local computer
  • Delete a container

Additional resources:

[!INCLUDE storage-multi-protocol-access-preview]

Prerequisites

Setting up

This section walks you through preparing a project to work with the Azure Blob Storage client library v12 for .NET.

Create the project

Create a .NET Core application named BlobQuickstartV12.

  1. In a console window (such as cmd, PowerShell, or Bash), use the dotnet new command to create a new console app with the name BlobQuickstartV12. This command creates a simple "Hello World" C# project with a single source file: Program.cs.

    dotnet new console -n BlobQuickstartV12

  2. Switch to the newly created BlobQuickstartV12 directory.

    cd BlobQuickstartV12

  3. In side the BlobQuickstartV12 directory, create another directory called data. This is where the blob data files will be created and stored.

    mkdir data

Install the package

While still in the application directory, install the Azure Blob Storage client library for .NET package by using the dotnet add package command.

dotnet add package Azure.Storage.Blobs

Set up the app framework

From the project directory:

  1. Open the Program.cs file in your editor.

  2. Remove the Console.WriteLine("Hello World!"); statement.

  3. Add using directives.

  4. Update the Main method declaration to support async.

    Here's the code:

    :::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/app_framework.cs":::

[!INCLUDE storage-quickstart-credentials-include]

Object model

Azure Blob Storage is optimized for storing massive amounts of unstructured data. Unstructured data is data that does not adhere to a particular data model or definition, such as text or binary data. Blob storage offers three types of resources:

  • The storage account
  • A container in the storage account
  • A blob in the container

The following diagram shows the relationship between these resources.

Diagram of Blob storage architecture

Use the following .NET classes to interact with these resources:

  • BlobServiceClient: The BlobServiceClient class allows you to manipulate Azure Storage resources and blob containers.
  • BlobContainerClient: The BlobContainerClient class allows you to manipulate Azure Storage containers and their blobs.
  • BlobClient: The BlobClient class allows you to manipulate Azure Storage blobs.

Code examples

These example code snippets show you how to perform the following with the Azure Blob Storage client library for .NET:

Get the connection string

The code below retrieves the connection string for the storage account from the environment variable created in the Configure your storage connection string section.

Add this code inside the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_ConnectionString":::

Create a container

Decide on a name for the new container. The code below appends a GUID value to the container name to ensure that it is unique.

Important

Container names must be lowercase. For more information about naming containers and blobs, see Naming and Referencing Containers, Blobs, and Metadata.

Create an instance of the BlobServiceClient class. Then, call the CreateBlobContainerAsync method to create the container in your storage account.

Add this code to the end of the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_CreateContainer":::

Upload blobs to a container

The following code snippet:

  1. Creates a text file in the local data directory.
  2. Gets a reference to a BlobClient object by calling the GetBlobClient method on the container from the Create a container section.
  3. Uploads the local text file to the blob by calling the ​Upload​Async method. This method creates the blob if it doesn't already exist, and overwrites it if it does.

Add this code to the end of the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_UploadBlobs":::

List the blobs in a container

List the blobs in the container by calling the GetBlobsAsync method. In this case, only one blob has been added to the container, so the listing operation returns just that one blob.

Add this code to the end of the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_ListBlobs":::

Download blobs

Download the previously created blob by calling the ​Download​To​Async method. The example code adds a suffix of "DOWNLOADED" to the file name so that you can see both files in local file system.

Add this code to the end of the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_DownloadBlobs":::

Delete a container

The following code cleans up the resources the app created by deleting the entire container by using ​DeleteAsync. It also deletes the local files created by the app.

The app pauses for user input by calling Console.ReadLine before it deletes the blob, container, and local files. This is a good chance to verify that the resources were actually created correctly, before they are deleted.

Add this code to the end of the Main method:

:::code language="csharp" source="~/azure-storage-snippets/blobs/quickstarts/dotnet/BlobQuickstartV12/Program.cs" id="Snippet_DeleteContainer":::

Run the code

This app creates a test file in your local data folder and uploads it to Blob storage. The example then lists the blobs in the container and downloads the file with a new name so that you can compare the old and new files.

Navigate to your application directory, then build and run the application.

dotnet build
dotnet run

The output of the app is similar to the following example:

Azure Blob Storage v12 - .NET quickstart sample

Uploading to Blob storage as blob:
         https://mystorageacct.blob.core.windows.net/quickstartblobs60c70d78-8d93-43ae-954d-8322058cfd64/quickstart2fe6c5b4-7918-46cb-96f4-8c4c5cb2fd31.txt

Listing blobs...
        quickstart2fe6c5b4-7918-46cb-96f4-8c4c5cb2fd31.txt

Downloading blob to
        ./data/quickstart2fe6c5b4-7918-46cb-96f4-8c4c5cb2fd31DOWNLOADED.txt

Press any key to begin clean up
Deleting blob container...
Deleting the local source and downloaded files...
Done

Before you begin the clean up process, check your data folder for the two files. You can open them and observe that they are identical.

After you've verified the files, press the Enter key to delete the test files and finish the demo.

Next steps

In this quickstart, you learned how to upload, download, and list blobs using .NET.

To see Blob storage sample apps, continue to:

[!div class="nextstepaction"] Azure Blob Storage SDK v12 .NET samples