SQL Server

Enumerate MIME Header Field Names

Demonstrates the Chilkat Mime.GetHeaderFieldName method, which returns the name of the header-field occurrence at a zero-based index. The only argument is the index; use NumHeaderFields for the count. Original order and casing are preserved.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: When you need to walk all the headers — to display them, copy them, or handle duplicates that GetHeaderField would hide — index-based access is the way. NumHeaderFields bounds the loop, and this returns each field's name in its original order and casing, which matters when the exact header sequence is significant.

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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 @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    EXEC sp_OAMethod @mime, 'LoadMimeFile', @success OUT, 'qa_data/message.eml'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @mime, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @mime
        RETURN
      END

    --  Iterate the header fields by index.  NumHeaderFields gives the count; GetHeaderFieldName and
    --  GetHeaderFieldValue return the name and value at each zero-based index.  Original order and
    --  casing are preserved.
    DECLARE @n int
    EXEC sp_OAGetProperty @mime, 'NumHeaderFields', @n OUT

    PRINT 'Header fields: ' + @n
    DECLARE @i int

    SELECT @i = 0
    WHILE @i <= @n - 1
      BEGIN
        DECLARE @fieldName nvarchar(4000)
        EXEC sp_OAMethod @mime, 'GetHeaderFieldName', @fieldName OUT, @i
        EXEC sp_OAGetProperty @mime, 'LastMethodSuccess', @iTmp0 OUT
        IF @iTmp0 = 0
          BEGIN
            EXEC sp_OAGetProperty @mime, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @mime
            RETURN
          END

        PRINT @fieldName
        SELECT @i = @i + 1
      END

    EXEC @hr = sp_OADestroy @mime


END
GO