Visual FoxPro

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. Visual FoxPro

LOCAL lnSuccess
LOCAL loRest
LOCAL lnBTls
LOCAL lnPort
LOCAL lnBAutoReconnect
LOCAL loAzAuth
LOCAL loSb
LOCAL loXml

lnSuccess = 0

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

loRest = CreateObject('Chilkat.Rest')

* Connect to the Azure Storage Blob Service
lnBTls = 1
lnPort = 443
lnBAutoReconnect = 1
* In this example, the storage account name is "chilkat".
lnSuccess = loRest.Connect("chilkat.blob.core.windows.net",lnPort,lnBTls,lnBAutoReconnect)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    CANCEL
ENDIF

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

* 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.
loSb = CreateObject('Chilkat.StringBuilder')
lnSuccess = loRest.FullRequestNoBodySb("GET","/test/helloWorldajdfadf.txt?comp=tags",loSb)
IF (lnSuccess = 0) THEN
    * Examine the request/response to see what happened.
    ? "response status code = " + STR(loRest.ResponseStatusCode)
    ? "response status text = " + loRest.ResponseStatusText
    ? "response header: " + loRest.ResponseHeader
    ? "---"
    ? "LastRequestStartLine: " + loRest.LastRequestStartLine
    ? "LastRequestHeader: " + loRest.LastRequestHeader
    RELEASE loRest
    RELEASE loAzAuth
    RELEASE loSb
    CANCEL
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>

? loSb.GetAsString()

* To see if we got Tags or an Error, then examine the XML.
loXml = CreateObject('Chilkat.Xml')
loXml.LoadSb(loSb,1)

* Examine the tag..
IF (loXml.TagEquals("Tags") = 1) THEN
    ? "Blob exists!"
ELSE

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

ENDIF

? "Success."

RELEASE loRest
RELEASE loAzAuth
RELEASE loSb
RELEASE loXml