B4X

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. B4X

Dim success As Boolean = False

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

Dim rest As ChilkatRest
rest.Initialize("rest")

'  Connect to the Azure Storage Blob Service
Dim bTls As Boolean = True
Dim port As Int = 443
Dim bAutoReconnect As Boolean = 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
    Log(rest.LastErrorText)
    Return
End If


'  Provide Azure Cloud credentials for the REST call.
Dim azAuth As ChilkatAuthAzureStorage
azAuth.Initialize
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 ChilkatStringBuilder
sb.Initialize
success = rest.FullRequestNoBodySb("GET", "/test/helloWorldajdfadf.txt?comp=tags", sb)
If success = False Then
    '  Examine the request/response to see what happened.
    Log("response status code = " & rest.ResponseStatusCode)
    Log("response status text = " & rest.ResponseStatusText)
    Log("response header: " & rest.ResponseHeader)
    Log("---")
    Log("LastRequestStartLine: " & rest.LastRequestStartLine)
    Log("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>

Log(sb.GetAsString)

'  To see if we got Tags or an Error, then examine the XML.
Dim xml As ChilkatXml
xml.Initialize
xml.LoadSb(sb, True)

'  Examine the tag..
If xml.TagEquals("Tags") = True Then
    Log("Blob exists!")
Else

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


End If


Log("Success.")