(C#) Azure Blob - Get Tags (Check if Blob Exists)

See more Azure Cloud Storage Examples

Gets the user-defined tags for a specified blob. This can also be used as a way to check to see if a blob exists.

For more information, see https://learn.microsoft.com/en-us/rest/api/storageservices/get-blob-tags

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Rest rest = new Chilkat.Rest();

// Connect to the Azure Storage Blob Service
bool bTls = true;
int port = 443;
bool bAutoReconnect = true;
// In this example, the storage account name is "chilkat".
bool success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// Provide Azure Cloud credentials for the REST call.
Chilkat.AuthAzureStorage azAuth = new Chilkat.AuthAzureStorage();
azAuth.AccessKey = "AZURE_ACCESS_KEY";
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.Account = "chilkat";
azAuth.Scheme = "SharedKey";
azAuth.Service = "Blob";
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = "2021-08-06";
success = rest.SetAuthAzureStorage(azAuth);

// Note: The application does not need to explicitly set the following
// headers: Content-Length, x-ms-date, Authorization.  These headers
// are automatically set by Chilkat.

// The Azure blob container is "test", the file is "helloWorld.txt"
// Add "?comp=tags" to get the user-defined tags instead of the actual blob content.
Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
success = rest.FullRequestNoBodySb("GET","/test/helloWorldajdfadf.txt?comp=tags",sb);
if (success == false) {
    // Examine the request/response to see what happened.
    Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
    Debug.WriteLine("response status text = " + rest.ResponseStatusText);
    Debug.WriteLine("response header: " + rest.ResponseHeader);
    Debug.WriteLine("---");
    Debug.WriteLine("LastRequestStartLine: " + rest.LastRequestStartLine);
    Debug.WriteLine("LastRequestHeader: " + rest.LastRequestHeader);
    return;
}

// A typical blob with no tags will return this:

// <?xml version="1.0" encoding="utf-8"?>
// <Tags><TagSet/></Tags>

// If the blob does not exist, you get this:

// <?xml version="1.0" encoding="utf-8"?>
// <Error>
//     <Code>BlobNotFound</Code>
//     <Message>The specified blob does not exist.
// 	RequestId:fcfefdd9-301e-001a-2135-3a23d2000000
// 	Time:2023-02-06T14:17:00.7805577Z
//     </Message>
// </Error>

Debug.WriteLine(sb.GetAsString());

// To see if we got Tags or an Error, then examine the XML.
Chilkat.Xml xml = new Chilkat.Xml();
xml.LoadSb(sb,true);

// Examine the tag..
if (xml.TagEquals("Tags") == true) {
    Debug.WriteLine("Blob exists!");
}
else {

    if (xml.ChildContentMatches("Code","BlobNotFound",true) == true) {
        Debug.WriteLine("Blob does not exist.");
    }
    else {
        Debug.WriteLine("Some other error...");
    }

}

Debug.WriteLine("Success.");