SQL Server

Save an Email to a Temporary MHT File

Demonstrates the Chilkat Email.CreateTempMht method, which prepares the email for display in a web browser and saves it as a temporary MHT file, returning the path that was written. If the filename argument is empty, Chilkat chooses a temporary filename.

To make the message viewable as a standalone web page, the method transforms it: all attachments are dropped; if the email has both HTML and plain-text alternatives, the plain-text alternative is dropped; and if the email has only a plain-text body, it is converted to HTML. This example loads an HTML email and creates the temporary MHT.

Background: MHT (MIME HTML) is a single-file web-page-archive format — it packs an HTML document together with its images and style sheets into one file, which is essentially what an HTML email already is. Because a Windows WebBrowser control can navigate directly to an .mht file, writing the message out as MHT is a quick way to render a received email, inline images and all, inside a desktop application. The transformations (dropping attachments, keeping just the HTML representation) ensure the result is a clean, self-contained page. For unpacking to loose files served by a web application instead, see AspUnpack.

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-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the CreateTempMht method, which prepares the email for viewing in a browser
    --  and saves it as a temporary MHT (MIME HTML) file, returning the file path.
    --  
    --  To produce browser-viewable output, CreateTempMht transforms the message: it drops all
    --  attachments; if the email has both HTML and plain-text alternatives it drops the
    --  plain-text alternative; and if the email has only a plain-text body it converts that
    --  body to HTML.  Passing an empty filename lets Chilkat choose a temporary filename.

    DECLARE @email int
    EXEC @hr = sp_OACreate 'Chilkat.Email', @email OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OAMethod @email, 'LoadEml', @success OUT, 'qa_data/eml/html_with_images.eml'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @email, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    --  Transform the email for browser display and save it as a temporary MHT file
    --  (empty filename = auto-generated temp file).
    DECLARE @mhtPath nvarchar(4000)
    EXEC sp_OAMethod @email, 'CreateTempMht', @mhtPath OUT, ''


    PRINT 'Temporary MHT file: ' + @mhtPath

    --  Note: The path "qa_data/..." is a relative local filesystem path,
    --  relative to the current working directory of the running application.

    EXEC @hr = sp_OADestroy @email


END
GO