Dart

The MIME Content-Type Header Field

See more MIME Examples

Explains the ContentType property and the Content-Type header field including the various attributes that may be included. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Every part in a MIME messsage should include a Content-Type header field.
  // The Content-Type indicates the type of content contained in the MIME part.
  // For example: text/plain, image/jpeg, application/pdf, application/json, multipart/mixed, etc.

  // Multipart content types are those where the MIME part's body is composed of N inner MIME messages,
  // separated by a boundary string.
  // This is how MIME gets a nested, tree-like structure.  The most common multipart MIME types
  // are (for email related MIME) multipart/mixed, multipart/alternative, and multipart/related,
  // and for HTTP related MIME, it is multipart/form-data.

  final mime = CkMime();

  // The Content-Type header field can be set or modified in two ways.
  // 1) By setting the ContentType, Micalg, Name, Charset, Boundary, or Protocol properties.
  //    Setting the ContentType property sets the primary value (such as "text/plain") of the header field.
  //    Each of the other properties listed above will replace or add a particular attribute value.

  // 2) By setting the entire contents of the ContentType header with the SetHeaderField method.
  //    This updates each of the Content-Type related properties.

  // For example:
  mime.contentType = 'text/plain';
  mime.charset = 'utf-8';

  // The Content-Type header field contains this:
  //     Content-Type: text/plain; charset=utf-8
  print(mime.getEntireHead());
  print('-');

  mime.setHeaderField('Content-Type', 'image/jpeg; name="kitty.jpg"');
  // The Content-Type header field now contains this:
  //     Content-Type: image/jpeg; name="kitty.jpg"
  print(mime.getEntireHead());
  print('-');

  // Notice how the properties have been updated:
  print('ContentType property: ${mime.contentType}');
  print('Charset property: ${mime.charset}');
  print('Name property: ${mime.name}');
  print('-');

  // To change a particular attribute value, set the property.
  mime.name = 'doggy.jpg';
  print(mime.getEntireHead());
  print('-');

  // To remove an attribute value from the Content-Type header,
  // set the property to an empty string.
  mime.name = '';
  print(mime.getEntireHead());
  print('-');
}