(Excel) The MIME Content-Type Header Field

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

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' 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.

Dim mime As Chilkat.Mime
Set mime = Chilkat.NewMime

' 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:
mime.ContentType = "text/plain"
mime.Charset = "utf-8"

' The Content-Type header field contains this:
'     Content-Type: text/plain; charset=utf-8
Debug.Print mime.GetEntireHead()
Debug.Print "-"

Dim success As Boolean
success = mime.SetHeaderField("Content-Type","image/jpeg; name=""kitty.jpg""")
' The Content-Type header field now contains this:
'     Content-Type: image/jpeg; name="kitty.jpg"
Debug.Print mime.GetEntireHead()
Debug.Print "-"

' Notice how the properties have been updated:
Debug.Print "ContentType property: "; mime.ContentType
Debug.Print "Charset property: "; mime.Charset
Debug.Print "Name property: "; mime.Name
Debug.Print "-"

' To change a particular attribute value, set the property.
mime.Name = "doggy.jpg"
Debug.Print mime.GetEntireHead()
Debug.Print "-"

' To remove an attribute value from the Content-Type header,
' set the property to an empty string.
mime.Name = ""
Debug.Print mime.GetEntireHead()
Debug.Print "-"