Xbase++

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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LOCAL nSuccess
LOCAL oEmail
LOCAL oBdImage
LOCAL cCid
LOCAL oSbHtml
LOCAL nNumReplaced
LOCAL cVal

nSuccess := 0

//  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.

oEmail := CreateObject("Chilkat.Email")
oEmail:Subject := "GetRelatedAttr example"

//  Load the image data from a file into a BinData object.
oBdImage := CreateObject("Chilkat.BinData")
nSuccess := oBdImage:LoadFile("qa_data/images/logo.png")
IF (nSuccess == 0)
    ? oBdImage:LastErrorText
    oEmail:destroy()
    oBdImage:destroy()
    RETURN
ENDIF

//  Add the image as a related item from the BinData; capture its generated Content-ID.
cCid := oEmail:AddRelatedBd("logo.png", oBdImage)
IF (oEmail:LastMethodSuccess == 0)
    ? oEmail:LastErrorText
    oEmail:destroy()
    oBdImage:destroy()
    RETURN
ENDIF

//  Reference the related item in the HTML body by its Content-ID.
oSbHtml := CreateObject("Chilkat.StringBuilder")
oSbHtml:Append('<html><body><img src="cid:PLACEHOLDER_CID"/></body></html>')
nNumReplaced := oSbHtml:Replace("PLACEHOLDER_CID", cCid)
oEmail:SetHtmlBody(oSbHtml:GetAsString())

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

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

oEmail:destroy()
oBdImage:destroy()
oSbHtml:destroy()