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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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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  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.

$email = New-Object Chilkat.Email
$email.Subject = "GetRelatedAttr example"

#  Load the image data from a file into a BinData object.
$bdImage = New-Object Chilkat.BinData
$success = $bdImage.LoadFile("qa_data/images/logo.png")
if ($success -eq $false) {
    $($bdImage.LastErrorText)
    exit
}

#  Add the image as a related item from the BinData; capture its generated Content-ID.
$cid = $email.AddRelatedBd("logo.png",$bdImage)
if ($email.LastMethodSuccess -eq $false) {
    $($email.LastErrorText)
    exit
}

#  Reference the related item in the HTML body by its Content-ID.
$sbHtml = New-Object Chilkat.StringBuilder
$sbHtml.Append("<html><body><img src=`"cid:PLACEHOLDER_CID`"/></body></html>")
$numReplaced = $sbHtml.Replace("PLACEHOLDER_CID",$cid)
$email.SetHtmlBody($sbHtml.GetAsString())

#  Get the "name" attribute of the related item's Content-Type header (index 0).
$val = $email.GetRelatedAttr(0,"Content-Type","name")
$("Related item Content-Type name attribute: " + $val)

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