(Go) Add, Remove, Update MIME Header Fields

Demonstrates how to add, remove, or update the content of MIME header fields.

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Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    mime := chilkat.NewMime()

    // The contents of this MIME file are shown below, 
    // and is also available at https://www.chilkatsoft.com/sampleMime.txt
    success := mime.LoadMimeFile("qa_data/mime/sampleMime.txt")
    if success != true {
        fmt.Println(mime.LastErrorText())
        mime.DisposeMime()
        return
    }

    // The MIME used in this example has the following nested structure
    // 
    // multipart/alternative
    //     text/plain
    //     multipart/related
    //         text/html
    //         image/jpeg
    // 

    // Adding a top-level MIME header is easy.
    mime.AddHeaderField("hello-world","Hello World!")
    // If a header field of the same name already exists, the AddHeaderField
    // method adds a duplicate.
    mime.AddHeaderField("Subject","This is the 2nd Subject header.")
    fmt.Println(*mime.GetEntireHead())
    fmt.Println("-")

    // The top-level header now looks like this:
    // 
    // 	Subject: Test email.
    // 	Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    // 	MIME-Version: 1.0
    // 	hello-world: Hello World!
    // 	Subject: This is the 2nd Subject header.
    // 

    // The RemoveHeaderField method can remove the 1st occurrance, or all occurrences.
    bAllOccurrences := true
    // Remove all occurrences of the Subject header;
    mime.RemoveHeaderField("Subject",bAllOccurrences)
    fmt.Println(*mime.GetEntireHead())
    fmt.Println("-")

    // After removing all Subject header fields, the top-level header now looks like this:
    // 
    // Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    // MIME-Version: 1.0
    // hello-world: Hello World!
    // 

    // The content of a header field can be updated by calling SetHeaderField.
    // If the header field does not already exist, it is added.  Otherwise it is updated.
    // Note: The order of header fields SHOULD never matter.
    mime.SetHeaderField("hello-world","Goodbye World.")
    fmt.Println(*mime.GetEntireHead())
    fmt.Println("-")

    // Now we have:
    // 
    // 	Content-Type: multipart/alternative; boundary="------------DB171738719FB06D67DEBAA0"
    // 	MIME-Version: 1.0
    // 	hello-world: Goodbye World.
    // 

    // To add/update/delete header fields in sub-parts, navigate to
    // the sub-part and do the same..

    mpRelated := mime.GetPart(1)
    pJpg := mpRelated.GetPart(1)

    // Add a header to the image/jpeg sub-header.
    pJpg.SetHeaderField("CustomHeader","This is the custom header value.")

    pJpg.DisposeMime()
    mpRelated.DisposeMime()

    // View the entire MIME..
    fmt.Println(*mime.GetMime())

    // --------------------------------------------------------------
    // --------------------------------------------------------------
    // The MIME sample file loaded at the beginning of this example
    // contains the following MIME:

    // Subject: Test email.
    // Content-Type: multipart/alternative;
    // 	boundary="------------DB171738719FB06D67DEBAA0"
    // MIME-Version: 1.0
    // 
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: text/plain; charset="utf-8"; format=flowed
    // Content-Transfer-Encoding: 7bit
    // 
    // This is a test.
    // 
    // --------------DB171738719FB06D67DEBAA0
    // Content-Type: multipart/related;
    // 	boundary="------------A940F1230E6F0105F03DB2CB"
    // 
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: text/html; charset="utf-8"
    // Content-Transfer-Encoding: 8bit
    // 
    // <html><head>
    // <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    //   </head>
    //   <body bgcolor="#FFFFFF" text="#000000">
    //     <p>This is a test.&nbsp; <img src="cid:part1.E16AE3B4.1505C436@chilkatsoft.com" height="20" width="20"></p>
    //   </body>
    // </html>
    // 
    // --------------A940F1230E6F0105F03DB2CB
    // Content-Type: image/jpeg; name="starfish20.jpg"
    // Content-Transfer-Encoding: base64
    // Content-ID: <part1.E16AE3B4.1505C436@chilkatsoft.com>
    // Content-Disposition: inline; filename="starfish20.jpg"
    // 
    // /9j/4AAQSkZJRgABAQEASABIAAD//gAmRmlsZSB3cml0dGVuIGJ5IEFkb2JlIFBob3Rvc2hvcD8g
    // NC4w/9sAQwAQCwwODAoQDg0OEhEQExgoGhgWFhgxIyUdKDozPTw5Mzg3QEhcTkBEV0U3OFBtUVdf
    // YmdoZz5NcXlwZHhcZWdj/9sAQwEREhIYFRgvGhovY0I4QmNjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj
    // Y2NjY2NjY2NjY2NjY2NjY2NjY2NjY2NjY2Nj/8IAEQgAFAAUAwERAAIRAQMRAf/EABcAAAMBAAAA
    // AAAAAAAAAAAAAAIDBAX/xAAYAQADAQEAAAAAAAAAAAAAAAABAgMEAP/aAAwDAQACEAMQAAAB2kZY
    // NNEijWKddfTmLgALWH//xAAbEAACAgMBAAAAAAAAAAAAAAABAgMRAAQSE//aAAgBAQABBQL0XqN+
    // pM2aqJGMiqFFCyg7z//EABwRAAICAgMAAAAAAAAAAAAAAAERAAIQIQMSUf/aAAgBAwEBPwHqU5aq
    // Axx+y1tMQl4elj//xAAcEQEAAQUBAQAAAAAAAAAAAAABEQACEBIhA1H/2gAIAQIBAT8B3Bhqy7Zc
    // enyiwmGgDhiOzj//xAAdEAABAwUBAAAAAAAAAAAAAAABAAIREBIhIkFR/9oACAEBAAY/ArZyn+Cg
    // xtxWuJaoCnqDuin/xAAcEAABBAMBAAAAAAAAAAAAAAABABEhYRAxQVH/2gAIAQEAAT8hkEwPUUR9
    // DYfE4nxtRpIkBTsayuALIiuY/9oADAMBAAIAAwAAABDWPTsf/8QAGhEAAwADAQAAAAAAAAAAAAAA
    // AAEREDFBIf/aAAgBAwEBPxC0DVPcWm+Ce4OesrkE6bjH/8QAGBEBAQEBAQAAAAAAAAAAAAAAAREA
    // QRD/2gAIAQIBAT8QahMiOc8YgSrnTY3ELclHXn//xAAcEAEBAAIDAQEAAAAAAAAAAAABEQAhMUFx
    // EFH/2gAIAQEAAT8Qn3igmSZSj+c4N4zapMy9IjFV98wncN2iuLFsCEbDGxQkI6RO/n//2Q==
    // 
    // --------------A940F1230E6F0105F03DB2CB--
    // 
    // --------------DB171738719FB06D67DEBAA0--
    // 

    mime.DisposeMime()