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Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

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llSuccess = .F.

//  Demonstrates the GetRelatedAttr method, which returns a header-field attribute value
//  from a header field of the Nth related item.  The first argument is the zero-based related-item
//  index, the second is the header field name, and the third is the attribute name.

loEmail = createobject("CkEmail")
loEmail.Subject = "GetRelatedAttr example"

//  Load the image data from a file into a BinData object.
loBdImage = createobject("CkBinData")
llSuccess = loBdImage.LoadFile("qa_data/images/logo.png")
if (llSuccess = .F.) then
    ? loBdImage.LastErrorText
    release loEmail
    release loBdImage
    return
endif

//  Add the image as a related item from the BinData; capture its generated Content-ID.
lcCid = loEmail.AddRelatedBd("logo.png",loBdImage)
if (loEmail.LastMethodSuccess = .F.) then
    ? loEmail.LastErrorText
    release loEmail
    release loBdImage
    return
endif

//  Reference the related item in the HTML body by its Content-ID.
loSbHtml = createobject("CkStringBuilder")
loSbHtml.Append('<html><body><img src="cid:PLACEHOLDER_CID"/></body></html>')
lnNumReplaced = loSbHtml.Replace("PLACEHOLDER_CID",lcCid)
loEmail.SetHtmlBody(loSbHtml.GetAsString())

//  Get the "name" attribute of the related item's Content-Type header (index 0).
lcVal = loEmail.GetRelatedAttr(0,"Content-Type","name")
? "Related item Content-Type name attribute: " + lcVal

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


release loEmail
release loBdImage
release loSbHtml