(C) 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.

For more information, see https://learn.microsoft.com/en-us/rest/api/storageservices/get-blob-tags

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#include <C_CkRest.h>
#include <C_CkAuthAzureStorage.h>
#include <C_CkStringBuilder.h>
#include <C_CkXml.h>

void ChilkatSample(void)
    {
    HCkRest rest;
    BOOL bTls;
    int port;
    BOOL bAutoReconnect;
    BOOL success;
    HCkAuthAzureStorage azAuth;
    HCkStringBuilder sb;
    HCkXml xml;

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

    rest = CkRest_Create();

    // Connect to the Azure Storage Blob Service
    bTls = TRUE;
    port = 443;
    bAutoReconnect = TRUE;
    // In this example, the storage account name is "chilkat".
    success = CkRest_Connect(rest,"chilkat.blob.core.windows.net",port,bTls,bAutoReconnect);
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        return;
    }

    // Provide Azure Cloud credentials for the REST call.
    azAuth = CkAuthAzureStorage_Create();
    CkAuthAzureStorage_putAccessKey(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_putAccount(azAuth,"chilkat");
    CkAuthAzureStorage_putScheme(azAuth,"SharedKey");
    CkAuthAzureStorage_putService(azAuth,"Blob");
    // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    CkAuthAzureStorage_putXMsVersion(azAuth,"2021-08-06");
    success = CkRest_SetAuthAzureStorage(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 = CkStringBuilder_Create();
    success = CkRest_FullRequestNoBodySb(rest,"GET","/test/helloWorldajdfadf.txt?comp=tags",sb);
    if (success == FALSE) {
        // Examine the request/response to see what happened.
        printf("response status code = %d\n",CkRest_getResponseStatusCode(rest));
        printf("response status text = %s\n",CkRest_responseStatusText(rest));
        printf("response header: %s\n",CkRest_responseHeader(rest));
        printf("---\n");
        printf("LastRequestStartLine: %s\n",CkRest_lastRequestStartLine(rest));
        printf("LastRequestHeader: %s\n",CkRest_lastRequestHeader(rest));
        CkRest_Dispose(rest);
        CkAuthAzureStorage_Dispose(azAuth);
        CkStringBuilder_Dispose(sb);
        return;
    }

    // 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>

    printf("%s\n",CkStringBuilder_getAsString(sb));

    // To see if we got Tags or an Error, then examine the XML.
    xml = CkXml_Create();
    CkXml_LoadSb(xml,sb,TRUE);

    // Examine the tag..
    if (CkXml_TagEquals(xml,"Tags") == TRUE) {
        printf("Blob exists!\n");
    }
    else {

        if (CkXml_ChildContentMatches(xml,"Code","BlobNotFound",TRUE) == TRUE) {
            printf("Blob does not exist.\n");
        }
        else {
            printf("Some other error...\n");
        }

    }

    printf("Success.\n");


    CkRest_Dispose(rest);
    CkAuthAzureStorage_Dispose(azAuth);
    CkStringBuilder_Dispose(sb);
    CkXml_Dispose(xml);

    }