Tcl

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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Tcl


load ./chilkat.dll

set success 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.

set email [new_CkEmail]

CkEmail_put_Subject $email "GetRelatedAttr example"

#  Load the image data from a file into a BinData object.
set bdImage [new_CkBinData]

set success [CkBinData_LoadFile $bdImage "qa_data/images/logo.png"]
if {$success == 0} then {
    puts [CkBinData_lastErrorText $bdImage]
    delete_CkEmail $email
    delete_CkBinData $bdImage
    exit
}

#  Add the image as a related item from the BinData; capture its generated Content-ID.
set cid [CkEmail_addRelatedBd $email "logo.png" $bdImage]
if {[CkEmail_get_LastMethodSuccess $email] == 0} then {
    puts [CkEmail_lastErrorText $email]
    delete_CkEmail $email
    delete_CkBinData $bdImage
    exit
}

#  Reference the related item in the HTML body by its Content-ID.
set sbHtml [new_CkStringBuilder]

CkStringBuilder_Append $sbHtml "<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>"
set numReplaced [CkStringBuilder_Replace $sbHtml "PLACEHOLDER_CID" $cid]
CkEmail_SetHtmlBody $email [CkStringBuilder_getAsString $sbHtml]

#  Get the "name" attribute of the related item's Content-Type header (index 0).
set val [CkEmail_getRelatedAttr $email 0 "Content-Type" "name"]
puts "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.

delete_CkEmail $email
delete_CkBinData $bdImage
delete_CkStringBuilder $sbHtml