NAME

Catalyst::Plugin::DetachIfNotModified - Short-circuit requests with If-Modified-Since headers

VERSION

version v0.2.1

SYNOPSIS

In your Catalyst class:

perl use Catalyst qw/ DetachIfNotModified /;

In a controller method:

```perl my $item = ...

$c->detach_if_not_modified_since( $item->timestamp );

Do some CPU-intensive stuff or generate response body here.

```

DESCRIPTION

This plugin will allow your Catalyst app to handle requests with If-Modified-Since headers.

If the content of a web page has not been modified since a given date, you can quickly bail out and avoid generating a web page that you do not need to.

This can improve the performance of your website.

This should be used with Plack::Middleware::ConditionalGET.

METHODS

detach_if_not_modified_since

$c->detach_if_not_modified_since( @timestamps );

This sets the Last-Modified header in the response to the maximum timestamp, and checks if the request contains a If-Modified-Since header that not less than the maximum timestamp. If it does, then it will set the response status code to 304 (Not Modified) and detach.

The @timestamps is a list of unix epochs or objects with an epoch method, such as a DateTime object.

This should only be used with GET or HEAD requests.

If you later need to reset the Last-Modified header after calling this method, you can use

$c->res->headers->remove_header('Last-Modified');

CAVEATS

Be careful when aggregating a collection of objects into a single timestamp, e.g. the maximum timestamp from a list. If a member is removed from that collection, then the maximum timestamp won't be affected, and the result is that an outdated web page may be cached by user agents.

SEE ALSO

Catalyst

Catalyst::Plugin::Cache::HTTP::Preempt

Plack::Middleware::ConditionalGET

RFC 7232 Section 3.3

SOURCE

The development version is on github at https://github.com/robrwo/Catalyst-Plugin-DetachIfNotModified and may be cloned from git://github.com/robrwo/Catalyst-Plugin-DetachIfNotModified.git

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/Catalyst-Plugin-DetachIfNotModified/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHOR

Robert Rothenberg rrwo@cpan.org

This module is based on code created for Science Photo Library https://www.sciencephoto.com.

COPYRIGHT AND LICENSE

This software is Copyright (c) 2020 by Robert Rothenberg.

This is free software, licensed under:

The Artistic License 2.0 (GPL Compatible)