NAME

MIME::Field::ContType - a "Content-type" field

DESCRIPTION

A subclass of Mail::Field.

Don't use this class directly... its name may change in the future! Instead, ask Mail::Field for new instances based on the field name!

SYNOPSIS

    use Mail::Field;
    use MIME::Head;
    # Create an instance from some text:
    $field = Mail::Field->new('Content-type',
                              'text/HTML; charset="US-ASCII"');
    # Get the MIME type, like 'text/plain' or 'x-foobar'.
    # Returns 'text/plain' as default, as per RFC 2045:
    my ($type, $subtype) = split('/', $field->type);
    # Get generic information:
    print $field->name;
    # Get information related to "message" type:
    if ($type eq 'message') {
        print $field->id;
        print $field->number;
        print $field->total;
    }
    # Get information related to "multipart" type:
    if ($type eq 'multipart') {
        print $field->boundary;            # the basic value, fixed up
        print $field->multipart_boundary;  # empty if not a multipart message!
    }
    # Get information related to "text" type:
    if ($type eq 'text') {
        print $field->charset;      # returns 'us-ascii' as default
    }

PUBLIC INTERFACE

boundary

Return the boundary field. The boundary is returned exactly as given in the "Content-type:" field; that is, the leading double-hyphen ("--") is not prepended.

(Well, almost exactly... from RFC 2046:

   (If a boundary appears to end with white space, the white space
   must be presumed to have been added by a gateway, and must be deleted.)

so we oblige and remove any trailing spaces.)

Returns the empty string if there is no boundary, or if the boundary is illegal (e.g., if it is empty after all trailing whitespace has been removed).

multipart_boundary

Like "boundary()", except that this will also return the empty string if the message is not a multipart message. In other words, there's an automatic sanity check.

type

Try real hard to determine the content type (e.g., "text/plain", "image/gif", "x-weird-type", which is returned in all-lowercase.

A happy thing: the following code will work just as you would want, even if there's no subtype (as in "x-weird-type")... in such a case, the $subtype would simply be the empty string:

    ($type, $subtype) = split('/', $head->mime_type);

If the content-type information is missing, it defaults to "text/plain", as per RFC 2045:

    Default RFC 2822 messages are typed by this protocol as plain text in
    the US-ASCII character set, which can be explicitly specified as
    "Content-type: text/plain; charset=us-ascii".  If no Content-Type is
    specified, this default is assumed.

Note: under the "be liberal in what we accept" principle, this routine no longer syntax-checks the content type. If it ain't empty, just downcase and return it.

NOTES

Since nearly all (if not all) parameters must have non-empty values to be considered valid, we just return the empty string to signify missing fields. If you need to get the real underlying value, use the inherited "param()" method (which returns undef if the parameter is missing).

AUTHOR