How to Read blob file from Microsoft Azure Storage with .NET Core

In order to read a blob file from a Microsoft Azure Blob Storage, you need to know the following:

  • The storage account connection string. This is the long string that looks like this:
    DefaultEndpointsProtocol=https;
    AccountName=someaccounfname;
    AccountKey=AVeryLongCrypticalStringThatContainsALotOfChars==
  • The blob storage container name. This is the name in the list of “Blobs”.
  • The blob file name. This is the name of the blob inside the container. A file name can be in form of a path, as blobs are structured as a file structure inside the container. For ecample: folder/folder/file.extension

You also need this NuGet package:

Windows.Azure.Storage

The code is pretty simple:

using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
 
public string GetBlob(string containerName, string fileName)
{
  string connectionString = $"yourconnectionstring";
 
  // Setup the connection to the storage account
  CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connectionString);
   
  // Connect to the blob storage
  CloudBlobClient serviceClient = storageAccount.CreateCloudBlobClient();
  // Connect to the blob container
  CloudBlobContainer container = serviceClient.GetContainerReference($"{containerName}");
  // Connect to the blob file
  CloudBlockBlob blob = container.GetBlockBlobReference($"{fileName}");
  // Get the blob file as text
  string contents = blob.DownloadTextAsync().Result;
   
  return contents;
}

The usage is equally easy:

GetBlob(“containername”, “my/file.json”);

Microservice and Idempotent method

Idempotent method is the one that results in same behavior either in a single or mutiple calls. For example a delete method will delete a resource
and return 204 first time. on subsequent calls it will return 404. return codes has nothting to do with idempotent behavior but the fact is that
behavior of call will always be the same.

+———+——+————+
| Method | Safe | Idempotent |
+———+——+————+
| CONNECT | no | no |
| DELETE | no | yes |
| GET | yes | yes |
| HEAD | yes | yes |
| OPTIONS | yes | yes |
| POST | no | no |
| PUT | no | yes |
| TRACE | yes | yes |
+———+——+————+

Reference

https://stackoverflow.com/questions/630453/what-is-the-difference-between-post-and-put-in-http