How to get content of Blob in Azure using .NET?-CodePudding

I met a problem when retrieving data from blob in Azure. My code is like follows:

static async Task Main()
        {   

            BlobServiceClient blobServiceClient = new BlobServiceClient("*");
            BlobContainerClient containerClient =  blobServiceClient.GetBlobContainerClient("*");
      
            var blobClient = containerClient.GetBlobClient("*");
            var content = blobClient.DownloadContent();

            BinaryData data = new BinaryData(content);
            var blobContents = Encoding.UTF8.GetString(data);
            Console.WriteLine("\t"   data);
}

But the result shows all the properties except the contents area:

{"Value":{"Details":{"BlobType":0,"ContentLength":66924,"ContentType":"application/octet-stream","ContentHash":"JwTlI7cLcG FWuewCaRuaQ==","LastModified":"2021-04-10T00:18:36 00:00","Metadata":{},"ContentRange":null,"ETag":"\u00220x8D8FBB62F1EC10C\u0022","ContentEncoding":null,"CacheControl":null,"ContentDisposition":null,"ContentLanguage":null,"BlobSequenceNumber":0,"CopyCompletedOn":"0001-01-01T00:00:00 00:00","CopyStatusDescription":null,"CopyId":null,"CopyProgress":null,"CopySource":null,"CopyStatus":0,"LeaseDuration":0,"LeaseState":0,"LeaseStatus":1,"AcceptRanges":"bytes","BlobCommittedBlockCount":0,"IsServerEncrypted":true,"EncryptionKeySha256":null,"EncryptionScope":null,"BlobContentHash":null,"TagCount":0,"VersionId":null,"IsSealed":false,"ObjectReplicationSourceProperties":null,"ObjectReplicationDestinationPolicyId":null,"LastAccessed":"0001-01-01T00:00:00 00:00","ImmutabilityPolicy":{"ExpiresOn":null,"PolicyMode":null},"HasLegalHold":false},"Content":{}}}

So I change my code as follows:

class Program
    {
        static async Task Main()
        {   

            BlobServiceClient blobServiceClient = new BlobServiceClient("*");
            BlobContainerClient containerClient =  blobServiceClient.GetBlobContainerClient("*");
            var blobClient = containerClient.GetBlobClient("*");  

            string localPath = "./data/tmp.datablock";
            blobClient.DownloadTo(localPath);
            
            string contents;
            using (StreamReader streamReader = new StreamReader("./data/tmp.datablock", Encoding.UTF8))
            {
                contents = streamReader.ReadToEnd();
            }

            var options = new JsonSerializerOptions { WriteIndented = true };
            string jsonString = System.Text.Json.JsonSerializer.Serialize(contents, options);
            Dictionary<string, dynamic>? values = JsonConvert.DeserializeObject<Dictionary<string, dynamic>>(contents);
            
            foreach(var pair in values)
            {
                Console.WriteLine(pair.Value);
            }  
        }
    }

And it works.

I just do not know why my first way can not work. And is there any better way to get the content of blob?

Thank all of you!

CodePudding user response：

Result of BlobClient.Download method is response of type BlobDownloadResult. To read the content of the blob, you will need to use the Content property there.

Please try the following code:

static async Task Main()
{   

    BlobServiceClient blobServiceClient = new BlobServiceClient("*");
    BlobContainerClient containerClient =  blobServiceClient.GetBlobContainerClient("*");

    var blobClient = containerClient.GetBlobClient("*");
    var response = blobClient.DownloadContent();

    BinaryData data = response.Value.Content;
    var blobContents = Encoding.UTF8.GetString(data);
    Console.WriteLine("\t"   data);
}