Can I get a blob by using its url?

Question

I am storing the Azure blob url into my database.Can I get the blob by using that url? Actually I need to update the blob and while doing that I need validations. So I need to convert that database entity model to my local model and apply the validations for them.But in my local model I am having Id,Name,HttpPostedFileBase file.When I am inserting the blob I am getting the blob url and saving it in database.But how to retrieve that blob while updating? This is my local Model

public class BlobAppModel
    {
        public int Id { get; set; }
        [Required(ErrorMessage="Please enter the name of the image")]
        [Remote("IsNameAvailable","Home",HttpMethod="POST",ErrorMessage="Name Already Exists")]
        public string Name { set; get; }
         [Required(ErrorMessage="Please select an image file")]
        public HttpPostedFileBase File { set; get; }

    } 

An My entitymodel is this one

public partial class BlobApp
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Uri { get; set; }
    }

when I am Editing it I need to get the blob ..I am stuck here..Can anyone help me out?

public ActionResult Edit(string Id)
        {
            var data=BlobManager.GetBlob(Convert.ToInt32(Id));
            BlobStorageServices _blobstorageservice = new BlobStorageServices();
            CloudBlobContainer container = _blobstorageservice.GetCloudBlobContainer();
            CloudBlockBlob blob = container.GetBlockBlobReference(data.Uri.ToString());

            BlobAppModel model = new BlobAppModel { Id = data.Id, Name = data.Name, File =//This is where I need to get the file//};
            return View("Edit",BlobManager.GetBlob(Convert.ToInt32(Id)));
        }

Answer 1

The best way to access a blob is by accessing the storage with the container name and the blob reference, as explained here: https://www.windowsazure.com/en-us/develop/net/how-to-guides/blob-storage/#download-blobs In your code you need to change the blob reference to the name you set when uploading, no to the uri.

CloudBlockBlob blob = container.GetBlockBlobReference(data.Uri.ToString());

use this instead:

CloudBlockBlob blob = container.GetBlockBlobReference("yourfile.jpg");

If you have the blob url, and the container is set to public access you can get the data by simply downloading it using a regular http client.

Answer 2

   CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
                ConfigurationManager.ConnectionStrings["StorageConnectionString"].ConnectionString);

    CloudBlockBlob blob = new CloudBlockBlob(new Uri(imgUrl),storageAccount.Credentials);

Answer 3

As Cristian also mentioned, you can use GetBlockBlobReference if you have the name of your blob. Otherwise, if you would like to use the full URL, you can simply create a new CloudBlockBlob object by using one of its constructors that take a Uri and a StorageCredentials object. You may not even need the StorageCredentials object if the Uri you have contains SAS credentials or the blob is public.

Answer 4

it is possible to get blob reference using blob Uri and container. For example if you need to update or delete blob and you already have container with credentials setup:

var blob = container.ServiceClient.GetBlobReferenceFromServer(blobUri);