PureBasic

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. PureBasic

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkRest.pb"
IncludeFile "CkAuthAzureStorage.pb"
IncludeFile "CkXml.pb"

Procedure ChilkatExample()

    success.i = 0

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

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect to the Azure Storage Blob Service
    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    ; In this example, the storage account name is "chilkat".
    success = CkRest::ckConnect(rest,"chilkat.blob.core.windows.net",port,bTls,bAutoReconnect)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; Provide Azure Cloud credentials for the REST call.
    azAuth.i = CkAuthAzureStorage::ckCreate()
    If azAuth.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkAuthAzureStorage::setCkAccessKey(azAuth, "AZURE_ACCESS_KEY")
    ; The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    CkAuthAzureStorage::setCkAccount(azAuth, "chilkat")
    CkAuthAzureStorage::setCkScheme(azAuth, "SharedKey")
    CkAuthAzureStorage::setCkService(azAuth, "Blob")
    ; This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    CkAuthAzureStorage::setCkXMsVersion(azAuth, "2021-08-06")
    success = CkRest::ckSetAuthAzureStorage(rest,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.
    sb.i = CkStringBuilder::ckCreate()
    If sb.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkRest::ckFullRequestNoBodySb(rest,"GET","/test/helloWorldajdfadf.txt?comp=tags",sb)
    If success = 0
        ; Examine the request/response to see what happened.
        Debug "response status code = " + Str(CkRest::ckResponseStatusCode(rest))
        Debug "response status text = " + CkRest::ckResponseStatusText(rest)
        Debug "response header: " + CkRest::ckResponseHeader(rest)
        Debug "---"
        Debug "LastRequestStartLine: " + CkRest::ckLastRequestStartLine(rest)
        Debug "LastRequestHeader: " + CkRest::ckLastRequestHeader(rest)
        CkRest::ckDispose(rest)
        CkAuthAzureStorage::ckDispose(azAuth)
        CkStringBuilder::ckDispose(sb)
        ProcedureReturn
    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>

    Debug CkStringBuilder::ckGetAsString(sb)

    ; To see if we got Tags or an Error, then examine the XML.
    xml.i = CkXml::ckCreate()
    If xml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkXml::ckLoadSb(xml,sb,1)

    ; Examine the tag..
    If CkXml::ckTagEquals(xml,"Tags") = 1
        Debug "Blob exists!"
    Else

        If CkXml::ckChildContentMatches(xml,"Code","BlobNotFound",1) = 1
            Debug "Blob does not exist."
        Else
            Debug "Some other error..."
        EndIf

    EndIf

    Debug "Success."


    CkRest::ckDispose(rest)
    CkAuthAzureStorage::ckDispose(azAuth)
    CkStringBuilder::ckDispose(sb)
    CkXml::ckDispose(xml)


    ProcedureReturn
EndProcedure