(Tcl) 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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load ./chilkat.dll

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

set rest [new_CkRest]

# Connect to the Azure Storage Blob Service
set bTls 1
set port 443
set bAutoReconnect 1
# In this example, the storage account name is "chilkat".
set success [CkRest_Connect $rest "chilkat.blob.core.windows.net" $port $bTls $bAutoReconnect]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

# Provide Azure Cloud credentials for the REST call.
set azAuth [new_CkAuthAzureStorage]

CkAuthAzureStorage_put_AccessKey $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_put_Account $azAuth "chilkat"
CkAuthAzureStorage_put_Scheme $azAuth "SharedKey"
CkAuthAzureStorage_put_Service $azAuth "Blob"
# This causes the "x-ms-version: 2021-08-06" header to be automatically added.
CkAuthAzureStorage_put_XMsVersion $azAuth "2021-08-06"
set 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.
set sb [new_CkStringBuilder]

set success [CkRest_FullRequestNoBodySb $rest "GET" "/test/helloWorldajdfadf.txt?comp=tags" $sb]
if {$success == 0} then {
    # Examine the request/response to see what happened.
    puts "response status code = [CkRest_get_ResponseStatusCode $rest]"
    puts "response status text = [CkRest_responseStatusText $rest]"
    puts "response header: [CkRest_responseHeader $rest]"
    puts "---"
    puts "LastRequestStartLine: [CkRest_lastRequestStartLine $rest]"
    puts "LastRequestHeader: [CkRest_lastRequestHeader $rest]"
    delete_CkRest $rest
    delete_CkAuthAzureStorage $azAuth
    delete_CkStringBuilder $sb
    exit
}

# 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>

puts [CkStringBuilder_getAsString $sb]

# To see if we got Tags or an Error, then examine the XML.
set xml [new_CkXml]

CkXml_LoadSb $xml $sb 1

# Examine the tag..
if {[CkXml_TagEquals $xml "Tags"] == 1} then {
    puts "Blob exists!"
} else {

    if {[CkXml_ChildContentMatches $xml "Code" "BlobNotFound" 1] == 1} then {
        puts "Blob does not exist."
    }     else {
        puts "Some other error..."
    }

}

puts "Success."

delete_CkRest $rest
delete_CkAuthAzureStorage $azAuth
delete_CkStringBuilder $sb
delete_CkXml $xml