Ubuntu Manpage: Plack::Request - Portable HTTP request object from PSGI env hash

NAME

       Plack::Request - Portable HTTP request object from PSGI env hash

SYNOPSIS

         use Plack::Request;

         my $app_or_middleware = sub {
             my $env = shift; # PSGI env

             my $req = Plack::Request->new($env);

             my $path_info = $req->path_info;
             my $query     = $req->parameters->{query};

             my $res = $req->new_response(200); # new Plack::Response
             $res->finalize;
         };

DESCRIPTION

       Plack::Request provides a consistent API for request objects across web server environments.

CAVEAT

       Note that this module is intended to be used by Plack middleware developers and web application framework
       developers rather than application developers (end users).

       Writing your web application directly using Plack::Request is certainly possible but not recommended:
       it's like doing so with mod_perl's Apache::Request: yet too low level.

       If you're writing a web application, not a framework, then you're encouraged to use one of the web
       application frameworks that support PSGI (<http://plackperl.org/#frameworks>), or see modules like
       HTTP::Engine to provide higher level Request and Response API on top of PSGI.

       If you're looking for an easy-to-use API to convert existing CGI applications to run on PSGI, consider
       using CGI::PSGI or CGI::Emulate::PSGI as well. CGI::Emulate::PSGI documentation has a good summary of
       using them to convert existing CGI scripts to adapt to PSGI.

METHODS

       Some of the methods defined in the earlier versions are deprecated in version 0.99. Take a look at
       "INCOMPATIBILITIES".

       Unless otherwise noted, all methods and attributes are read-only, and passing values to the method like
       an accessor doesn't work like you expect it to.

   new
           Plack::Request->new( $env );

       Creates a new request object.

ATTRIBUTES

env Returns the shared PSGI environment hash reference. This is a reference, so writing to this
environment passes through during the whole PSGI request/response cycle.

address
Returns the IP address of the client ("REMOTE_ADDR").

remote_host
Returns the remote host ("REMOTE_HOST") of the client. It may be empty, in which case you have to get
the IP address using "address" method and resolve on your own.

method
Contains the request method ("GET", "POST", "HEAD", etc).

protocol
Returns the protocol (HTTP/1.0 or HTTP/1.1) used for the current request.

request_uri
Returns the raw, undecoded request URI path. You probably do NOT want to use this to dispatch
requests.

path_info
Returns PATH_INFO in the environment. Use this to get the local path for the requests.

path
Similar to "path_info" but returns "/" in case it is empty. In other words, it returns the virtual
path of the request URI after "$req->base". See "DISPATCHING" for details.

query_string
Returns QUERY_STRING in the environment. This is the undecoded query string in the request URI.

script_name
Returns SCRIPT_NAME in the environment. This is the absolute path where your application is hosted.

scheme
Returns the scheme ("http" or "https") of the request.

secure
Returns true or false, indicating whether the connection is secure (https).

body, input
Returns "psgi.input" handle.

session
Returns (optional) "psgix.session" hash. When it exists, you can retrieve and store per-session data
from and to this hash.

session_options
Returns (optional) "psgix.session.options" hash.

logger
Returns (optional) "psgix.logger" code reference. When it exists, your application is supposed to
send the log message to this logger, using:

$req->logger->({ level => 'debug', message => "This is a debug message" });

cookies
Returns a reference to a hash containing the cookies. Values are strings that are sent by clients and
are URI decoded.

If there are multiple cookies with the same name in the request, this method will ignore the
duplicates and return only the first value. If that causes issues for you, you may have to use
modules like CGI::Simple::Cookie to parse "$request->header('Cookie')" by yourself.

query_parameters
Returns a reference to a hash containing query string (GET) parameters. This hash reference is
Hash::MultiValue object.

body_parameters
Returns a reference to a hash containing posted parameters in the request body (POST). As with
"query_parameters", the hash reference is a Hash::MultiValue object.

parameters
Returns a Hash::MultiValue hash reference containing (merged) GET and POST parameters.

content, raw_body
Returns the request content in an undecoded byte string for POST requests.

uri Returns an URI object for the current request. The URI is constructed using various environment
values such as "SCRIPT_NAME", "PATH_INFO", "QUERY_STRING", "HTTP_HOST", "SERVER_NAME" and
"SERVER_PORT".

Every time this method is called it returns a new, cloned URI object.

base
Returns an URI object for the base path of current request. This is like "uri" but only contains up
to "SCRIPT_NAME" where your application is hosted at.

Every time this method is called it returns a new, cloned URI object.

user
Returns "REMOTE_USER" if it's set.

headers
Returns an HTTP::Headers::Fast object containing the headers for the current request.

uploads
Returns a reference to a hash containing uploads. The hash reference is a Hash::MultiValue object and
values are Plack::Request::Upload objects.

content_encoding
Shortcut to $req->headers->content_encoding.

content_length
Shortcut to $req->headers->content_length.

content_type
Shortcut to $req->headers->content_type.

header
Shortcut to $req->headers->header.

referer
Shortcut to $req->headers->referer.

user_agent
Shortcut to $req->headers->user_agent.

param
Returns GET and POST parameters with a CGI.pm-compatible param method. This is an alternative method
for accessing parameters in $req->parameters just in case you want the compatibility with CGI.pm
objects.

You are not recommended to use this method since it is easy to misuse in a list context such as
inside a hash constructor or method arguments. Use "parameters" and Hash::MultiValue instead.

Unlike CGI.pm, it does not allow setting or modifying query parameters.

$value = $req->param( 'foo' );
@values = $req->param( 'foo' );
@params = $req->param;

upload
A convenient method to access $req->uploads.

$upload = $req->upload('field');
@uploads = $req->upload('field');
@fields = $req->upload;

for my $upload ( $req->upload('field') ) {
print $upload->filename;
}

new_response
my $res = $req->new_response;

Creates a new Plack::Response object. Handy to remove dependency on Plack::Response in your code for
easy subclassing and duck typing in web application frameworks, as well as overriding Response
generation in middlewares.

Hash::MultiValue parameters
Parameters that can take one or multiple values (i.e. "parameters", "query_parameters", "body_parameters"
and "uploads") store the hash reference as a Hash::MultiValue object. This means you can use the hash
reference as a plain hash where values are always scalars (NOT array references), so you don't need to
code ugly and unsafe "ref ... eq 'ARRAY'" anymore.

And if you explicitly want to get multiple values of the same key, you can call the "get_all" method on
it, such as:

my @foo = $req->query_parameters->get_all('foo');

You can also call "get_one" to always get one parameter independent of the context (unlike "param"), and
even call "mixed" (with Hash::MultiValue 0.05 or later) to get the traditional hash reference,

my $params = $req->parameters->mixed;

where values are either a scalar or an array reference depending on input, so it might be useful if you
already have the code to deal with that ugliness.

PARSING POST BODY and MULTIPLE OBJECTS
The methods to parse request body ("content", "body_parameters" and "uploads") are carefully coded to
save the parsed body in the environment hash as well as in the temporary buffer, so you can call them
multiple times and create Plack::Request objects multiple times in a request and they should work safely,
and won't parse request body more than twice for the efficiency.

DISPATCHING

       If  your application or framework wants to dispatch (or route) actions based on request paths, be sure to
       use "$req->path_info" not "$req->uri->path".

       This is because "path_info" gives you the virtual path of the request, regardless of how your application
       is mounted. If your application is hosted with mod_perl or CGI scripts, or even  multiplexed  with  tools
       like Plack::App::URLMap, request's "path_info" always gives you the action path.

       Note  that  "path_info"  might give you an empty string, in which case you should assume that the path is
       "/".

       You will also want to use "$req->base" as a base prefix when  building  URLs  in  your  templates  or  in
       redirections. It's a good idea for you to subclass Plack::Request and define methods such as:

         sub uri_for {
             my($self, $path, $args) = @_;
             my $uri = $self->base;
             $uri->path($uri->path . $path);
             $uri->query_form(@$args) if $args;
             $uri;
         }

       So you can say:

         my $link = $req->uri_for('/logout', [ signoff => 1 ]);

       and if "$req->base" is "/app" you'll get the full URI for "/app/logout?signoff=1".

INCOMPATIBILITIES

In version 0.99, many utility methods are removed or deprecated, and most methods are made read-only.
These methods were deleted in version 1.0001.

All parameter-related methods such as "parameters", "body_parameters", "query_parameters" and "uploads"
now contains Hash::MultiValue objects, rather than scalar or an array reference depending on the user
input which is insecure. See Hash::MultiValue for more about this change.

"$req->path" method had a bug, where the code and the document was mismatching. The document was
suggesting it returns the sub request path after "$req->base" but the code was always returning the
absolute URI path. The code is now updated to be an alias of "$req->path_info" but returns "/" in case
it's empty. If you need the older behavior, just call "$req->uri->path" instead.

Cookie handling is simplified, and doesn't use CGI::Simple::Cookie anymore, which means you CAN NOT set
array reference or hash reference as a cookie value and expect it be serialized. You're always required
to set string value, and encoding or decoding them is totally up to your application or framework. Also,
"cookies" hash reference now returns strings for the cookies rather than CGI::Simple::Cookie objects,
which means you no longer have to write a wacky code such as:

$v = $req->cookies->{foo} ? $req->cookies->{foo}->value : undef;

and instead, simply do:

$v = $req->cookies->{foo};

AUTHORS

       Tatsuhiko Miyagawa

       Kazuhiro Osawa

       Tokuhiro Matsuno

LICENSE

       This  library  is  free  software;  you can redistribute it and/or modify it under the same terms as Perl
       itself.

perl v5.30.0                                       2019-10-23                                Plack::Request(3pm)