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.\"
.IX Title "Plack::Middleware::HTTPExceptions 3pm"
.TH Plack::Middleware::HTTPExceptions 3pm "2011-06-22" "perl v5.14.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Plack::Middleware::HTTPExceptions \- Catch HTTP exceptions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use HTTP::Exception;
\&
\&  my $app = sub {
\&      # ...
\&      HTTP::Exception::500\->throw;
\&  };
\&
\&  builder {
\&      enable "HTTPExceptions", rethrow => 1;
\&      $app;
\&  };
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Plack::Middleware::HTTPExceptions is a \s-1PSGI\s0 middleware component to
catch exceptions from applications that can be translated into \s-1HTTP\s0
status codes.
.PP
Your application is supposed to throw an object that implements a
\&\f(CW\*(C`code\*(C'\fR method which returns the \s-1HTTP\s0 status code, such as 501 or
404. This middleware catches them and creates a valid response out of
the code. If the \f(CW\*(C`code\*(C'\fR method returns a code that is not an \s-1HTTP\s0
redirect or error code (3xx, 4xx, or 5xx), the exception will be
rethrown.
.PP
The exception object may also implement \f(CW\*(C`as_string\*(C'\fR or overload
stringification to represent the text of the error. The text defaults to
the status message of the error code, such as \fIService Unavailable\fR for
\&\f(CW503\fR.
.PP
Finally, the exception object may implement \f(CW\*(C`as_psgi\*(C'\fR, and the result
of this will be returned directly as the \s-1PSGI\s0 response.
.PP
If the code is in the 3xx range and the exception implements the 'location'
method (HTTP::Exception::3xx does), the Location header will be set in the
response, so you can do redirects this way.
.PP
There are \s-1CPAN\s0 modules HTTP::Exception and HTTP::Throwable, and
they are perfect to throw from your application to let this middleware
catch and display, but you can also implement your own exception class
to throw.
.PP
If the thrown exception is not an object that implements either a
\&\f(CW\*(C`code\*(C'\fR or an \f(CW\*(C`as_psgi\*(C'\fR method, a 500 error will be returned.
Alternatively, you can pass a true value for the \f(CW\*(C`rethrow\*(C'\fR parameter
for this middleware, and the exception will instead be rethrown. This is
enabled by default when \f(CW\*(C`PLACK_ENV\*(C'\fR is set to \f(CW\*(C`development\*(C'\fR, so that
the StackTrace middleware can catch it
instead.
.SH "AUTHOR"
.IX Header "AUTHOR"
Tatsuhiko Miyagawa
.SH "SEE ALSO"
.IX Header "SEE ALSO"
paste.httpexceptions HTTP::Exception HTTP::Throwable