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. C++

#include <CkRest.h>
#include <CkAuthAzureStorage.h>
#include <CkStringBuilder.h>
#include <CkXml.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkRest rest;

    //  Connect to the Azure Storage Blob Service
    bool bTls = true;
    int port = 443;
    bool bAutoReconnect = true;
    //  In this example, the storage account name is "chilkat".
    success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect);
    if (success != true) {
        std::cout << rest.lastErrorText() << "\r\n";
        return;
    }

    //  Provide Azure Cloud credentials for the REST call.
    CkAuthAzureStorage azAuth;
    azAuth.put_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.put_Account("chilkat");
    azAuth.put_Scheme("SharedKey");
    azAuth.put_Service("Blob");
    //  This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    azAuth.put_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.
    CkStringBuilder sb;
    success = rest.FullRequestNoBodySb("GET","/test/helloWorldajdfadf.txt?comp=tags",sb);
    if (success == false) {
        //  Examine the request/response to see what happened.
        std::cout << "response status code = " << rest.get_ResponseStatusCode() << "\r\n";
        std::cout << "response status text = " << rest.responseStatusText() << "\r\n";
        std::cout << "response header: " << rest.responseHeader() << "\r\n";
        std::cout << "---" << "\r\n";
        std::cout << "LastRequestStartLine: " << rest.lastRequestStartLine() << "\r\n";
        std::cout << "LastRequestHeader: " << rest.lastRequestHeader() << "\r\n";
        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>

    std::cout << sb.getAsString() << "\r\n";

    //  To see if we got Tags or an Error, then examine the XML.
    CkXml xml;
    xml.LoadSb(sb,true);

    //  Examine the tag..
    if (xml.TagEquals("Tags") == true) {
        std::cout << "Blob exists!" << "\r\n";
    }
    else {

        if (xml.ChildContentMatches("Code","BlobNotFound",true) == true) {
            std::cout << "Blob does not exist." << "\r\n";
        }
        else {
            std::cout << "Some other error..." << "\r\n";
        }

    }

    std::cout << "Success." << "\r\n";
    }