Tcl

Read the REST Response Body into BinData

Demonstrates Rest.ReadRespBd, which reads the response body as raw bytes into a BinData, replacing its previous contents.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background. The staged request model separates sending from reading: a SendReq method transmits the request, ReadResponseHeader reads the status line and headers, and a ReadResp method reads the body. This gives fine control over large or streamed messages compared with the single-call full-request methods.

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Tcl


load ./chilkat.dll

set success 0

set rest [new_CkRest]

set bTls 1
set bAutoReconnect 1
set success [CkRest_Connect $rest "example.com" 443 $bTls $bAutoReconnect]
if {$success == 0} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

#  The file paths are relative to the application's current working directory.  Absolute paths
#  may also be used.  Supply the paths appropriate to your own environment.

set success [CkRest_SendReqNoBody $rest "GET" "/api/images/1"]
if {$success == 0} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

set statusCode [CkRest_ReadResponseHeader $rest]
if {$statusCode < 0} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

#  Check for the expected success status code.  If the response is not 200, the body is likely
#  error text formatted as JSON, XML, or HTML rather than the expected binary content.  In that case
#  read the body as text, report it, and return.
if {$statusCode != 200} then {
    set sbError [new_CkStringBuilder]

    set success [CkRest_ReadRespSb $rest $sbError]
    if {$success == 0} then {
        puts [CkRest_lastErrorText $rest]
        delete_CkRest $rest
        delete_CkStringBuilder $sbError
        exit
    }

    puts "Request failed with status code $statusCode"
    puts [CkStringBuilder_getAsString $sbError]
    delete_CkRest $rest
    delete_CkStringBuilder $sbError
    exit
}

#  The status code is 200.  Read the response body as raw bytes into a BinData.
set bdResponse [new_CkBinData]

set success [CkRest_ReadRespBd $rest $bdResponse]
if {$success == 0} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkStringBuilder $sbError
    delete_CkBinData $bdResponse
    exit
}

set bSaved [CkBinData_WriteFile $bdResponse "qa_output/image.png"]
if {$bSaved != 1} then {
    puts "Failed to save the response body."
    delete_CkRest $rest
    delete_CkStringBuilder $sbError
    delete_CkBinData $bdResponse
    exit
}

puts "Received [CkBinData_get_NumBytes $bdResponse] bytes."

delete_CkRest $rest
delete_CkStringBuilder $sbError
delete_CkBinData $bdResponse