Dart

Save an Email to a Temporary MHT File

Demonstrates the Chilkat Email.CreateTempMht method, which prepares the email for display in a web browser and saves it as a temporary MHT file, returning the path that was written. If the filename argument is empty, Chilkat chooses a temporary filename.

To make the message viewable as a standalone web page, the method transforms it: all attachments are dropped; if the email has both HTML and plain-text alternatives, the plain-text alternative is dropped; and if the email has only a plain-text body, it is converted to HTML. This example loads an HTML email and creates the temporary MHT.

Background: MHT (MIME HTML) is a single-file web-page-archive format — it packs an HTML document together with its images and style sheets into one file, which is essentially what an HTML email already is. Because a Windows WebBrowser control can navigate directly to an .mht file, writing the message out as MHT is a quick way to render a received email, inline images and all, inside a desktop application. The transformations (dropping attachments, keeping just the HTML representation) ensure the result is a clean, self-contained page. For unpacking to loose files served by a web application instead, see AspUnpack.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the CreateTempMht method, which prepares the email for viewing in a browser
  // and saves it as a temporary MHT (MIME HTML) file, returning the file path.
  // 
  // To produce browser-viewable output, CreateTempMht transforms the message: it drops all
  // attachments; if the email has both HTML and plain-text alternatives it drops the
  // plain-text alternative; and if the email has only a plain-text body it converts that
  // body to HTML.  Passing an empty filename lets Chilkat choose a temporary filename.

  final email = CkEmail();

  try {
    email.loadEml('qa_data/eml/html_with_images.eml');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Transform the email for browser display and save it as a temporary MHT file
  // (empty filename = auto-generated temp file).
  final mhtPath = email.createTempMht('');

  print('Temporary MHT file: $mhtPath');

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