DataFlex

Building a multipart/form-data Request for HTTP Upload

See more HTTP Examples

Uploading files to a web server typically requires building a multipart/form-data request where the files are contained in the sub-parts of the MIME request.

Note: HTTP uploads require code on the server-side to receive the upload. For example, see Complete C# ASP.NET HTTP Upload Example

This example produces the following HTTP multipart/form-data request:

POST /something HTTP/1.1
Content-Type: multipart/form-data; boundary=------------070002080409050901090203
Host: domain
Content-Length: 546

--------------070002080409050901090203
Content-Disposition: form-data; name="fileA"; filename="fileA.txt"
Content-Type: text/plain

This is the contents of file A
--------------070002080409050901090203
Content-Disposition: form-data; name="fileB"; filename="fileB.txt"
Content-Type: text/plain

This is the contents of file B
--------------070002080409050901090203
Content-Disposition: form-data; name="fileC"; filename="fileC.txt"
Content-Type: text/plain

This is the contents of file C
--------------070002080409050901090203--

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoReq
    Boolean iSuccess
    String sRequestMime

    // This example demonstrates building a multipart/form-data request.

    Get Create (RefClass(cComChilkatHttpRequest)) To hoReq
    If (Not(IsComObjectCreated(hoReq))) Begin
        Send CreateComObject of hoReq
    End

    // The ContentType, HttpVerb, and Path properties should
    // always be explicitly set.
    Set ComHttpVerb Of hoReq To "POST"
    Set ComPath Of hoReq To "/something"
    Set ComContentType Of hoReq To "multipart/form-data"

    // The contents and name of each file to be uploaded is provided
    // by calling any of the following methods:
    // AddBytesForUpload
    // AddBytesForUpload2
    // AddFileForUpload
    // AddFileForUpload2
    // AddStringForUpload
    // AddStringForUpload2

    // For this example, we'll provide the contents of the files to be uploaded
    // directly as in-memory strings.
    Get ComAddStringForUpload Of hoReq "fileA" "fileA.txt" "This is the contents of file A" "utf-8" To iSuccess
    Get ComAddStringForUpload Of hoReq "fileB" "fileB.txt" "This is the contents of file B" "utf-8" To iSuccess
    Get ComAddStringForUpload Of hoReq "fileC" "fileC.txt" "This is the contents of file C" "utf-8" To iSuccess

    // View the request that would be sent if HttpSReq was called:
    Get ComGenerateRequestText Of hoReq To sRequestMime
    Showln sRequestMime

    // A few important comments about the HTTP request that is generated:
    // 
    // 1) Chilkat automatically generates a random boundary string.   In 99.999% of cases, this should 
    //    be sufficient.
    // 2) The Content-Length header is automatically generated based on the actual length of the MIME message
    //    that follows the intial (topmost) MIME header.
    // 3) The HOST header will automatically get filled in with the actual domain when HttpSReq
    //    is called


End_Procedure