Xojo Plugin

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. Xojo Plugin

Dim success As Boolean
success = False

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

Dim rest As New Chilkat.Rest

// Connect to the Azure Storage Blob Service
Dim bTls As Boolean
bTls = True
Dim port As Int32
port = 443
Dim bAutoReconnect As Boolean
bAutoReconnect = True
// In this example, the storage account name is "chilkat".
success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect)
If (success <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

// Provide Azure Cloud credentials for the REST call.
Dim azAuth As 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.
Dim sb As New Chilkat.StringBuilder
success = rest.FullRequestNoBodySb("GET","/test/helloWorldajdfadf.txt?comp=tags",sb)
If (success = False) Then
    // Examine the request/response to see what happened.
    System.DebugLog("response status code = " + Str(rest.ResponseStatusCode))
    System.DebugLog("response status text = " + rest.ResponseStatusText)
    System.DebugLog("response header: " + rest.ResponseHeader)
    System.DebugLog("---")
    System.DebugLog("LastRequestStartLine: " + rest.LastRequestStartLine)
    System.DebugLog("LastRequestHeader: " + rest.LastRequestHeader)
    Return
End If

// 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>

System.DebugLog(sb.GetAsString())

// To see if we got Tags or an Error, then examine the XML.
Dim xml As New Chilkat.Xml
success = xml.LoadSb(sb,True)

// Examine the tag..
If (xml.TagEquals("Tags") = True) Then
    System.DebugLog("Blob exists!")
Else

    If (xml.ChildContentMatches("Code","BlobNotFound",True) = True) Then
        System.DebugLog("Blob does not exist.")
    Else
        System.DebugLog("Some other error...")
    End If

End If

System.DebugLog("Success.")