Xbase++

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. Xbase++

LOCAL nSuccess
LOCAL oRest
LOCAL nBTls
LOCAL nPort
LOCAL nBAutoReconnect
LOCAL oAzAuth
LOCAL oSb
LOCAL oXml

nSuccess := 0

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

oRest := CreateObject("Chilkat.Rest")

//  Connect to the Azure Storage Blob Service
nBTls := 1
nPort := 443
nBAutoReconnect := 1
//  In this example, the storage account name is "chilkat".
nSuccess := oRest:Connect("chilkat.blob.core.windows.net", nPort, nBTls, nBAutoReconnect)
IF (nSuccess != 1)
    ? oRest:LastErrorText
    oRest:destroy()
    RETURN
ENDIF

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

//  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.
oSb := CreateObject("Chilkat.StringBuilder")
nSuccess := oRest:FullRequestNoBodySb("GET", "/test/helloWorldajdfadf.txt?comp=tags", oSb)
IF (nSuccess == 0)
    //  Examine the request/response to see what happened.
    ? "response status code = " + Str(oRest:ResponseStatusCode)
    ? "response status text = " + oRest:ResponseStatusText
    ? "response header: " + oRest:ResponseHeader
    ? "---"
    ? "LastRequestStartLine: " + oRest:LastRequestStartLine
    ? "LastRequestHeader: " + oRest:LastRequestHeader
    oRest:destroy()
    oAzAuth:destroy()
    oSb:destroy()
    RETURN
ENDIF

//  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>

? oSb:GetAsString()

//  To see if we got Tags or an Error, then examine the XML.
oXml := CreateObject("Chilkat.Xml")
oXml:LoadSb(oSb, 1)

//  Examine the tag..
IF (oXml:TagEquals("Tags") == 1)
    ? "Blob exists!"
ELSE

    IF (oXml:ChildContentMatches("Code", "BlobNotFound", 1) == 1)
        ? "Blob does not exist."
    ELSE
        ? "Some other error..."
    ENDIF

ENDIF

? "Success."

oRest:destroy()
oAzAuth:destroy()
oSb:destroy()
oXml:destroy()