DataFlex
REST Stream Multipart Body from File

Demonstrates how to send a multipart/form-data HTTP request, where one of the parts contains data streamed directly from a file. This is good for cases where the file to be uploaded is very large.
Chilkat DataFlex Downloads

Download Chilkat for DataFlex
DataFlex
Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoRest
    Boolean iBTls
    Integer iPort
    Boolean iBAutoReconnect
    Variant vSbHtml
    Handle hoSbHtml
    Variant vFileStream
    Handle hoFileStream
    String sResponseBody
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End

    // Connect to the destination web server.
    Move True To iBTls
    Move 443 To iPort
    Move True To iBAutoReconnect
    Get ComConnect Of hoRest "www.somewebserver.com" iPort iBTls iBAutoReconnect To iSuccess

    // This example will send the following multipart/form-data request.
    // The Content-Length is automatically computed and added by Chilkat.

    // 	POST /some_path HTTP/1.1
    // 	Content-Type: multipart/form-data; boundary=---------------------------735323031399963166993862150
    // 	Content-Length: 834
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="text1"
    // 
    // 	text 123 abc
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="text2"
    // 
    // 	xyz
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file1"; filename="a.txt"
    // 	Content-Type: text/plain
    // 
    // 	Content of a.txt.
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file2"; filename="a.html"
    // 	Content-Type: text/html
    // 
    // 	<!DOCTYPE html><title>Content of a.html.</title>
    // 
    // 	-----------------------------735323031399963166993862150
    // 	Content-Disposition: form-data; name="file3"; filename="starfish.jpg"
    // 	Content-Type: image/jpeg
    // 
    // 	binary data goes here
    // 	-----------------------------735323031399963166993862150--

    // Set the Content-Type for the topmost MIME part.
    Get ComAddHeader Of hoRest "Content-Type" "multipart/form-data" To iSuccess

    // Specify each part of the request.
    Set ComPartSelector Of hoRest To "1"
    Get ComAddHeader Of hoRest "Content-Disposition" 'form-data; name="text1"' To iSuccess
    Get ComSetMultipartBodyString Of hoRest "text 123 abc" To iSuccess

    Set ComPartSelector Of hoRest To "2"
    Get ComAddHeader Of hoRest "Content-Disposition" 'form-data; name="text2"' To iSuccess
    Get ComSetMultipartBodyString Of hoRest "xyz" To iSuccess

    Set ComPartSelector Of hoRest To "3"
    Get ComAddHeader Of hoRest "Content-Disposition" 'form-data; name="file1"; filename="a.txt"' To iSuccess
    Get ComAddHeader Of hoRest "Content-Type" "text/plain" To iSuccess
    Get ComSetMultipartBodyString Of hoRest "Content of a.txt." To iSuccess

    Set ComPartSelector Of hoRest To "4"
    Get ComAddHeader Of hoRest "Content-Disposition" 'form-data; name="file2"; filename="a.html"' To iSuccess
    Get ComAddHeader Of hoRest "Content-Type" "text/html" To iSuccess
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbHtml
    If (Not(IsComObjectCreated(hoSbHtml))) Begin
        Send CreateComObject of hoSbHtml
    End
    Get ComLoadFile Of hoSbHtml "qa_data/html/a.html" "utf-8" To iSuccess
    Get pvComObject of hoSbHtml to vSbHtml
    Get ComSetMultipartBodySb Of hoRest vSbHtml To iSuccess

    Set ComPartSelector Of hoRest To "5"
    Get ComAddHeader Of hoRest "Content-Disposition" 'form-data; name="file3"; filename="starfish.jpg"' To iSuccess
    Get ComAddHeader Of hoRest "Content-Type" "image/jpeg" To iSuccess

    // When the request is sent, stream this part directly from the file.
    // This avoids having to load the entire file into memory.
    Get Create (RefClass(cComChilkatStream)) To hoFileStream
    If (Not(IsComObjectCreated(hoFileStream))) Begin
        Send CreateComObject of hoFileStream
    End
    Set ComSourceFile Of hoFileStream To "qa_data/jpg/starfish.jpg"
    Get pvComObject of hoFileStream to vFileStream
    Get ComSetMultipartBodyStream Of hoRest vFileStream To iSuccess

    Get ComFullRequestMultipart Of hoRest "POST" "/some_path" To sResponseBody
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // ...
    // ...

    // Clear the REST object for any subsequent requests..
    Get ComClearAllHeaders Of hoRest To iSuccess
    Get ComClearAllParts Of hoRest To iSuccess
    Set ComPartSelector Of hoRest To ""


End_Procedure