Dart

Get a Header Attribute of an Attached Message

Demonstrates the Chilkat Email.GetAttachedMessageAttr method, which returns a header-field attribute value for the Nth attached (embedded) email. The first argument is the zero-based attached-message index, the second is the header field name, and the third is the attribute name. This example attaches an email and reads the filename attribute of its Content-Disposition header.

Background: MIME header fields can carry named attributes (parameters) after the main value — for example Content-Disposition: attachment; filename="report.eml", where filename is an attribute. Rather than parsing the raw header yourself, this method extracts a single named attribute from a chosen header of a specific embedded message, which is convenient when a message forwards other emails as nested message/rfc822 parts.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the GetAttachedMessageAttr method, which returns a header-field attribute
  // value for the Nth attached (embedded) email.  The first argument is the zero-based
  // attached-message index, the second is the header field name, and the third is the attribute name.

  // Build an inner email to attach.
  final innerEmail = CkEmail();
  innerEmail.subject = 'Embedded message';
  innerEmail.from = 'alice@example.com';
  innerEmail.addTo('Bob', 'bob@example.com');

  // Attach it to an outer email as a message/rfc822 part.
  final email = CkEmail();
  email.subject = 'Has an attached message';
  try {
    email.attachEmail(innerEmail);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the "filename" attribute of the "Content-Disposition" header of the first
  // attached message (index 0).
  final fname = email.getAttachedMessageAttr(0, 'Content-Disposition', 'filename');
  print('Attached message filename attribute: $fname');
}