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Manual Reference Pages  -  PLACK::REQUEST (3)

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



  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


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


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 (<>), or see modules like HTTP::Engine to provide higher level Request and Response API on top of PSGI.


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 <B>read-onlyB>, and passing values to the method like an accessor doesn’t work like you expect it to.


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

Creates a new request object.


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 <B>NOTB> want to use this to dispatch requests.
path_info Returns <B>PATH_INFOB> 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 <B>QUERY_STRINGB> in the environment. This is the undecoded query string in the request URI.
script_name Returns <B>SCRIPT_NAMEB> 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(Cookies) 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 param method. This is an alternative method for accessing parameters in $req->parameters just in case you want the compatibility with objects.

You are <B>not recommendedB> 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, 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;


  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 <B>alwaysB> scalars (<B>NOTB> 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.


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.


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;

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.


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 <B>CAN NOTB> 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};


Tatsuhiko Miyagawa

Kazuhiro Osawa

Tokuhiro Matsuno


Plack::Response HTTP::Request, Catalyst::Request


This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
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perl v5.20.3 PLACK::REQUEST (3) 2015-06-03

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