(PureBasic) 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 PureBasic Module Download

Chilkat PureBasic Module

IncludeFile "CkStream.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkRest.pb"

Procedure ChilkatExample()

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

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect to the destination web server.
    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    success.i = CkRest::ckConnect(rest,"www.somewebserver.com",port,bTls,bAutoReconnect)

    ; 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.
    CkRest::ckAddHeader(rest,"Content-Type","multipart/form-data")

    ; Specify each part of the request.
    CkRest::setCkPartSelector(rest, "1")
    CkRest::ckAddHeader(rest,"Content-Disposition","form-data; name=" + Chr(34) + "text1" + Chr(34))
    CkRest::ckSetMultipartBodyString(rest,"text 123 abc")

    CkRest::setCkPartSelector(rest, "2")
    CkRest::ckAddHeader(rest,"Content-Disposition","form-data; name=" + Chr(34) + "text2" + Chr(34))
    CkRest::ckSetMultipartBodyString(rest,"xyz")

    CkRest::setCkPartSelector(rest, "3")
    CkRest::ckAddHeader(rest,"Content-Disposition","form-data; name=" + Chr(34) + "file1" + Chr(34) + "; filename=" + Chr(34) + "a.txt" + Chr(34))
    CkRest::ckAddHeader(rest,"Content-Type","text/plain")
    CkRest::ckSetMultipartBodyString(rest,"Content of a.txt.")

    CkRest::setCkPartSelector(rest, "4")
    CkRest::ckAddHeader(rest,"Content-Disposition","form-data; name=" + Chr(34) + "file2" + Chr(34) + "; filename=" + Chr(34) + "a.html" + Chr(34))
    CkRest::ckAddHeader(rest,"Content-Type","text/html")
    sbHtml.i = CkStringBuilder::ckCreate()
    If sbHtml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckLoadFile(sbHtml,"qa_data/html/a.html","utf-8")
    CkRest::ckSetMultipartBodySb(rest,sbHtml)

    CkRest::setCkPartSelector(rest, "5")
    CkRest::ckAddHeader(rest,"Content-Disposition","form-data; name=" + Chr(34) + "file3" + Chr(34) + "; filename=" + Chr(34) + "starfish.jpg" + Chr(34))
    CkRest::ckAddHeader(rest,"Content-Type","image/jpeg")

    ; When the request is sent, stream this part directly from the file.
    ; This avoids having to load the entire file into memory.
    fileStream.i = CkStream::ckCreate()
    If fileStream.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStream::setCkSourceFile(fileStream, "qa_data/jpg/starfish.jpg")
    CkRest::ckSetMultipartBodyStream(rest,fileStream)

    responseBody.s = CkRest::ckFullRequestMultipart(rest,"POST","/some_path")
    If CkRest::ckLastMethodSuccess(rest) <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        CkStringBuilder::ckDispose(sbHtml)
        CkStream::ckDispose(fileStream)
        ProcedureReturn
    EndIf

    ; ...
    ; ...

    ; Clear the REST object for any subsequent requests..
    CkRest::ckClearAllHeaders(rest)
    CkRest::ckClearAllParts(rest)
    CkRest::setCkPartSelector(rest, "")


    CkRest::ckDispose(rest)
    CkStringBuilder::ckDispose(sbHtml)
    CkStream::ckDispose(fileStream)


    ProcedureReturn
EndProcedure