NAME
CGI::Header - Handle CGI.pm-compatible HTTP header properties
SYNOPSIS
use CGI;
use CGI::Header;
my $query = CGI->new;
# CGI.pm-compatible HTTP header properties
my $header = CGI::Header->new(
query => $query,
header => {
attachment => 'foo.gif',
charset => 'utf-7',
cookies => [ $cookie1, $cookie2 ], # CGI::Cookie objects
expires => '+3d',
nph => 1,
p3p => [qw/CAO DSP LAW CURa/],
target => 'ResultsWindow',
type => 'image/gif'
},
);
# update $header
$header->set( 'Content-Length' => 3002 ); # overwrite
$header->delete('Content-Disposition'); # => 3002
$header->clear; # => $self
$header->as_string; # => "Content-Type: text/html\n..."
VERSION
This document refers to CGI::Header version 0.52.
DEPENDENCIES
This module is compatible with CGI.pm 3.51 or higher.
DESCRIPTION
This module is a utility class to manipulate a hash reference received
by CGI.pm's "header()" method.
This module isn't the replacement of the "header()" method, but
complements CGI.pm.
This module can be used in the following situation:
1. $header is a hash reference which represents CGI response headers
For example, CGI::Application implements "header_add()" method which
can be used to add CGI.pm-compatible HTTP header properties.
Instances of CGI.pm-based applications often hold those properties.
my $header = { type => 'text/plain' };
2. Manipulates $header using CGI::Header
Since property names are case-insensitive, application developers
have to normalize them manually when they specify header properties.
CGI::Header normalizes them automatically.
use CGI::Header;
my $h = CGI::Header->new( header => $header );
$h->set( 'Content-Length' => 3002 ); # add Content-Length header
$header;
# => {
# 'type' => 'text/plain',
# 'content-length' => '3002',
# }
3. Passes $header to CGI::header() to stringify the variable
use CGI;
print CGI::header( $header );
# Content-length: 3002
# Content-Type: text/plain; charset=ISO-8859-1
#
"header()" function just stringifies given header properties. This
module can be used to generate PSGI-compatible response header array
references. See CGI::Header::PSGI.
ATTRIBUTES
$header->query
Returns your current query object. This attribute defaults to the
Singleton instance of CGI.pm ($CGI::Q), which is shared by functions
exported by the module.
$hashref = $header->header
Returns the header hash reference associated with this CGI::Header
object. This attribute defaults to a reference to an empty hash. The
hashref will be passed to CGI.pm's "header" method to generate CGI
response headers. See "CGI::Header#as_string".
METHODS
$value = $header->get( $field )
$value = $header->set( $field => $value )
Get or set the value of the header field. The header field name
($field) is not case sensitive.
# field names are case-insensitive
$header->get('Content-Length');
$header->get('content-length');
The $value argument must be a plain string:
$header->set( 'Content-Length' => 3002 );
my $length = $header->get('Content-Length'); # => 3002
$bool = $header->exists( $field )
Returns a Boolean value telling whether the specified field exists.
if ( $header->exists('ETag') ) {
...
}
$value = $header->delete( $field )
Deletes the specified field form CGI response headers. Returns the
value of the deleted field.
my $value = $header->delete('Content-Disposition'); # => 'inline'
$self = $header->clear
This will remove all header properties.
$header->as_string
It's identical to:
$header->query->header( $header->header );
$header->clone
Returns a copy of this "CGI::Header" object. The "query" object is
shared. The "header" hashref is copied shallowly. It's identical to:
# surface copy
my %header = %{ $original->header };
my $clone = CGI::Header->new(
query => $original->query, # shares query object
header => \%header
);
PROPERTIES
The following methods were named after property names recognized by
CGI.pm's "header" method. Most of these methods can both be used to read
and to set the value of a property.
If you pass an argument to the method, the property value will be set,
and also the current object itself will be returned; therefore you can
chain methods as follows:
$header->type('text/html')->charset('utf-8');
If no argument is supplied, the property value will be returned. If the
given property doesn't exist, "undef" will be returned.
$self = $header->attachment( $filename )
$filename = $header->attachment
Get or set the "attachment" property. Can be used to turn the page
into an attachment. Represents suggested name for the saved file.
$header->attachment('genome.jpg');
In this case, the outgoing header will be formatted as:
Content-Disposition: attachment; filename="genome.jpg"
$self = $header->charset( $character_set )
$character_set = $header->charset
Get or set the "charset" property. Represents the character set sent
to the browser.
$self = $header->cookies([ $cookie1, $cookie2, ... ])
$cookies = $header->cookies
Get or set the "cookies" property.
$self = $header->expires( $format )
$format = $header->expires
Get or set the "expires" property. The Expires header gives the date
and time after which the entity should be considered stale. You can
specify an absolute or relative expiration interval. The following
forms are all valid for this field:
$header->expires( '+30s' ); # 30 seconds from now
$header->expires( '+10m' ); # ten minutes from now
$header->expires( '+1h' ); # one hour from now
$header->expires( 'now' ); # immediately
$header->expires( '+3M' ); # in three months
$header->expires( '+10y' ); # in ten years time
# at the indicated time & date
$header->expires( 'Thu, 25 Apr 1999 00:40:33 GMT' );
$self = $header->location( $url )
$url = $header->location
Get or set the Location header.
$header->location('http://somewhere.else/in/movie/land');
$self = $header->nph( $bool )
$bool = $header->nph
Get or set the "nph" property. If set to a true value, will issue
the correct headers to work with a NPH (no-parse-header) script.
$header->nph(1);
$tags = $header->p3p
$self = $header->p3p( $tags )
Get or set the "p3p" property. The parameter can be an arrayref or a
space-delimited string.
$header->p3p([qw/CAO DSP LAW CURa/]);
# or
$header->p3p('CAO DSP LAW CURa');
In this case, the outgoing header will be formatted as:
P3P: policyref="/w3c/p3p.xml", CP="CAO DSP LAW CURa"
$self = $header->redirect( $url[, $status] );
Sets redirect URL with an optional status code and a human-readable
message, which defaults to "302 Found". Returns this object itself.
$header->redirect('http://somewhere.else/in/movie/land');
$self = $header->status( $status )
$status = $header->status
Get or set the Status header.
$header->status('304 Not Modified');
$self = $header->target( $window_target )
$window_target = $header->target
Get or set the Window-Target header.
$header->target('ResultsWindow');
$self = $header->type( $media_type )
$media_type = $header->type
Get or set the "type" property. Represents the media type of the
message content.
$header->type('text/html');
NORMALIZING PROPERTY NAMES
This class normalizes property names automatically. Normalized property
names are:
1. lowercased
'Content-Length' -> 'content-length'
2. use dashes instead of underscores in property name
'content_length' -> 'content-length'
CGI.pm's "header" method also accepts aliases of property names. This
module converts them as follows:
'content-type' -> 'type'
'cookie' -> 'cookies'
'set-cookie' -> 'cookies'
'window-target' -> 'target'
If a property name is duplicated, throws an exception:
my $header = CGI::Header->new(
header => {
-Type => 'text/plain',
Content_Type => 'text/html',
}
);
# die "Property '-type' already exists"
EXAMPLES
WRITING Blosxom PLUGINS
The following plugin just adds the Content-Length header to CGI response
headers sent by blosxom.cgi:
package content_length;
use CGI::Header;
sub start {
!$blosxom::static_entries;
}
sub last {
my $h = CGI::Header->new( header => $blosxom::header )->rehash;
$h->set( 'Content-Length' => length $blosxom::output );
}
1;
Since Blosxom <http://blosxom.sourceforge.net/> depends on the
procedural interface of CGI.pm, you don't have to pass $query to "new()"
in this case.
HANDLING HTTP COOKIES
It's up to you to decide how to manage HTTP cookies.
use parent 'CGI::Header';
# Add cookie() attribute which defaults a reference to an empty hash.
# The keys of the hash are the cookies' names, and their corresponding
# values are a plain string, e.g., "$header->cookie->{ID} = 123456"
sub cookie {
$_[0]->{cookie} ||= {};
}
# The 'cookies' property defaults to an arrayref
sub cookies {
$_[0]->header->{cookies} ||= [];
}
# Override as_string() to create and set CGI::Cookie objects right before
# stringifying header props.
sub as_string {
my $self = shift;
my $query = $self->query;
my $cookies = $self->cookies;
while ( my ($name, $value) = each %{$self->cookie} ) {
push @{$cookies}, $query->cookie( $name => $value );
}
$self->SUPER::as_string;
}
WORKING WITH CGI::Simple
Since CGI::Simple is "a relatively lightweight drop in replacement for
CGI.pm", this module is compatible with the module. If you're using the
procedural interface of the module (CGI::Simple::Standard), you need to
override the "_build_query" method as follows:
use parent 'CGI::Header';
use CGI::Simple::Standard;
sub _build_query {
# NOTE: loader() is designed for debugging
CGI::Simple::Standard->loader('_cgi_object');
}
LIMITATIONS
Since the following strings conflict with property names, you can't use
them as field names ($field):
"Attachment"
"Charset"
"Cookie"
"Cookies"
"NPH"
"Target"
"Type"
Content-Type
If you don't want to send the Content-Type header, set the "type"
property to an empty string, though it's far from intuitive
manipulation:
$header->type(q{});
# doesn't work as you expect
$header->delete('Content-Type');
$header->type(undef);
Date
If one of the following conditions is met, the Date header will be
set automatically, and also the header field will become read-only:
if ( $header->nph or $header->cookie or $header->expires ) {
$header->set( 'Date' => 'Thu, 25 Apr 1999 00:40:33 GMT' ); # wrong
$header->delete('Date'); # wrong
}
P3P You can't assign to the P3P header directly:
# wrong
$header->set( 'P3P' => '/path/to/p3p.xml' );
"CGI::header()" restricts where the policy-reference file is
located, and so you can't modify the location ("/w3c/p3p.xml").
You're allowed to set P3P tags using "p3p()".
Pragma
If the following condition is met, the Pragma header will be set
automatically, and also the header field will become read-only:
if ( $header->query->cache ) {
$header->set( 'Pragma' => 'no-cache' ); # wrong
$header->delete('Pragma'); # wrong
}
Server
If the following condition is met, the Server header will be set
automatically, and also the header field will become read-only:
if ( $header->nph ) {
$header->set( 'Server' => 'Apache/1.3.27 (Unix)' ); # wrong
$header->delete('Server'); # wrong
}
SEE ALSO
CGI, HTTP::Headers
BUGS
There are no known bugs in this module. Please report problems to
ANAZAWA (anazawa@cpan.org). Patches are welcome.
AUTHOR
Ryo Anazawa (anazawa@cpan.org)
LICENSE
This module is free software; you can redistibute it and/or modify it
under the same terms as Perl itself. See perlartistic.