Dart

Convert a MIME Entity to multipart/mixed

Demonstrates the Chilkat Mime.ConvertToMultipartMixed method, which wraps the current entity in a new outer multipart/mixed, making the original the first child. It takes no arguments.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This is how you turn an existing single-part message into one that can hold attachments — rather than rebuilding it, you wrap it, and its content becomes the first child of a new multipart/mixed. Message-level and custom headers are carried onto the new outer entity so the message identity is preserved. Afterward, AppendPartFromFile adds attachments beside the original body.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final mime = CkMime();
  try {
    mime.loadMimeFile('qa_data/message.eml');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Wrap the current entity in a new outer multipart/mixed entity.  The original entity becomes the
  // first child, which is what you do to add attachments to an existing single-part message.
  try {
    mime.convertToMultipartMixed();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Now attachments can be appended alongside the original content.
  try {
    mime.appendPartFromFile('qa_data/report.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Number of parts: ${mime.numParts}');
}