(SQL Server) The MIME Content-Type Header Field

Explains the ContentType property and the Content-Type header field including the various attributes that may be included.

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
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- Every part in a MIME messsage should include a Content-Type header field.
    -- The Content-Type indicates the type of content contained in the MIME part.
    -- For example: text/plain, image/jpeg, application/pdf, application/json, multipart/mixed, etc.

    -- Multipart content types are those where the MIME part's body is composed of N inner MIME messages,
    -- separated by a boundary string.
    -- This is how MIME gets a nested, tree-like structure.  The most common multipart MIME types
    -- are (for email related MIME) multipart/mixed, multipart/alternative, and multipart/related,
    -- and for HTTP related MIME, it is multipart/form-data.

    DECLARE @success int

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

    -- The Content-Type header field can be set or modified in two ways.
    -- 1) By setting the ContentType, Micalg, Name, Charset, Boundary, or Protocol properties.
    --    Setting the ContentType property sets the primary value (such as "text/plain") of the header field.
    --    Each of the other properties listed above will replace or add a particular attribute value.

    -- 2) By setting the entire contents of the ContentType header with the SetHeaderField method.
    --    This updates each of the Content-Type related properties.

    -- For example:
    EXEC sp_OASetProperty @mime, 'ContentType', 'text/plain'
    EXEC sp_OASetProperty @mime, 'Charset', 'utf-8'

    -- The Content-Type header field contains this:
    --     Content-Type: text/plain; charset=utf-8
    EXEC sp_OAMethod @mime, 'GetEntireHead', @sTmp0 OUT
    PRINT @sTmp0

    PRINT '-'

    EXEC sp_OAMethod @mime, 'SetHeaderField', @success OUT, 'Content-Type', 'image/jpeg; name="kitty.jpg"'
    -- The Content-Type header field now contains this:
    --     Content-Type: image/jpeg; name="kitty.jpg"
    EXEC sp_OAMethod @mime, 'GetEntireHead', @sTmp0 OUT
    PRINT @sTmp0

    PRINT '-'

    -- Notice how the properties have been updated:

    EXEC sp_OAGetProperty @mime, 'ContentType', @sTmp0 OUT
    PRINT 'ContentType property: ' + @sTmp0

    EXEC sp_OAGetProperty @mime, 'Charset', @sTmp0 OUT
    PRINT 'Charset property: ' + @sTmp0

    EXEC sp_OAGetProperty @mime, 'Name', @sTmp0 OUT
    PRINT 'Name property: ' + @sTmp0

    PRINT '-'

    -- To change a particular attribute value, set the property.
    EXEC sp_OASetProperty @mime, 'Name', 'doggy.jpg'
    EXEC sp_OAMethod @mime, 'GetEntireHead', @sTmp0 OUT
    PRINT @sTmp0

    PRINT '-'

    -- To remove an attribute value from the Content-Type header,
    -- set the property to an empty string.
    EXEC sp_OASetProperty @mime, 'Name', ''
    EXEC sp_OAMethod @mime, 'GetEntireHead', @sTmp0 OUT
    PRINT @sTmp0

    PRINT '-'

    EXEC @hr = sp_OADestroy @mime


END
GO