Introduction
Blob storage is an azure service
to store large size/amount of data in unstructured way in form of binaries in
the cloud. This opens up the whole world of files and all their extensions
which can be uploaded in the blobs.
This post does not talk about the creation of blobs,
connections but explains step by step in uploading the files, downloading the
files and moving the files from one blob to another.
Upload file
The first step in the process of uploading a file to Blob is
to create Objects of the CloudStorageAccount and the BlobClients in it.
|
// Retrieve storage account from connection string.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(UnityConfiguration.GetConfigurationValue("ConfigKey"));
// Create the blob client object from the storage
account
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
|
You may want to add Retry policy to this blobClient which
will retry to access the client in an exponential time if there is any problem
encountered in the first try
|
blobClient.DefaultRequestOptions.RetryPolicy
= new ExponentialRetry(TimeSpan.FromSeconds(retryInterval),
retryCount);
|
It is always a best practice to check if the Blob exists
with a container, this way you can throw an exception that blob does not exists
or create one with the container reference.
|
// Returns an reference for a given container of the
blob
CloudBlobContainer blobContainer = blobClient.GetContainerReference(
UnityConfiguration.GetConfigurationValue("ContainerName"));
// Create container if it doesn’t exists
blobContainer.CreateIfNotExists();
|
Now that we have completed all the pre-requisites, the next
step is to create reference of the CloudBlockBlob and then upload the file
|
// Create the reference of the block blob from the
container
CloudBlockBlob blockBlob = blobContainer.GetBlockBlobReference(this.AddLocationInfo("Blobname"));
|
|
using (var inputStream = new MemoryStream())
{
document.Save(inputStream); // document is a file object(could be xml,
image, etc)
inputStream.Flush();
inputStream.Position = 0;
blob.UploadFromStream(inputStream);
}
Note:
a. For
XmlDocument
document
-> document.Save(inputStream)
b. For
other type of files (.docx, .xlsx, etc) need to save into a stream so that it
can be uploaded to blob.
|
Download file
Downloading a file is simple, you can download a file
content into a Stream or as a string or even as a byte array.
The CloudBlockBlob object has method to download the file
|
// Download the file as memory stream
using (var blobStream =
blockBlob.OpenRead())
{
MemoryStream
contentStream = new MemoryStream();
blobStream.CopyTo(contentStream);
}
|
|
// Download the file as string
Encoding
encoding;
blockBlob.DownloadText(encoding);
|
|
// Download the file into byte array
byte[] content;
using (var memoryStream = new MemoryStream())
{
blockBlob.DownloadToStream(memoryStream);
content = memoryStream.ToArray();
}
|
Moving file from
one Blob to another
To move a file from one blob to another, simply use the
inbuilt method of the CloudBlockBlob object.
|
CloudBlockBlob
source;
CloudBlockBlob
target;
using (var sourceStream =
source.OpenRead())
{
target.UploadFromStream(sourceStream);
}
|
Please leave your feedback and queries in the comments
section. Thank you!
