(SQL Server) Building a multipart/form-data Request for HTTP Upload

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--

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- This example demonstrates building a multipart/form-data request.

    DECLARE @req int
    -- Use "Chilkat_9_5_0.HttpRequest" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.HttpRequest', @req OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- The ContentType, HttpVerb, and Path properties should
    -- always be explicitly set.
    EXEC sp_OASetProperty @req, 'HttpVerb', 'POST'
    EXEC sp_OASetProperty @req, 'Path', '/something'
    EXEC sp_OASetProperty @req, 'ContentType', '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.
    DECLARE @success int
    EXEC sp_OAMethod @req, 'AddStringForUpload', @success OUT, 'fileA', 'fileA.txt', 'This is the contents of file A', 'utf-8'
    EXEC sp_OAMethod @req, 'AddStringForUpload', @success OUT, 'fileB', 'fileB.txt', 'This is the contents of file B', 'utf-8'
    EXEC sp_OAMethod @req, 'AddStringForUpload', @success OUT, 'fileC', 'fileC.txt', 'This is the contents of file C', 'utf-8'

    -- View the request that would be sent if SynchronousRequest was called:
    DECLARE @requestMime nvarchar(4000)
    EXEC sp_OAMethod @req, 'GenerateRequestText', @requestMime OUT

    PRINT @requestMime

    -- 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 SynchronousRequest
    --    is called

    EXEC @hr = sp_OADestroy @req


END
GO