Perl

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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use strict;
use warnings;
use Chilkat2;

# 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.

my $email = Chilkat2::Email->new;
$email->Subject('GetRelatedAttr example');

# Load the image data from a file into a BinData object.
my $bdImage = Chilkat2::BinData->new;
my $success = $bdImage->LoadFile('qa_data/images/logo.png');
if (!$success) {
    print $bdImage->LastErrorText, "\n";
    exit;
}

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

# Reference the related item in the HTML body by its Content-ID.
my $sbHtml = Chilkat2::StringBuilder->new;
$sbHtml->Append('<html><body><img src="cid:PLACEHOLDER_CID"/></body></html>');
my $numReplaced = $sbHtml->Replace('PLACEHOLDER_CID', $cid);
$email->SetHtmlBody($sbHtml->GetAsString());

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

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