Re: Setting Content-Type in a custom response (mp2)

On Thursday 11 March 2010 15:18:08 Steve Hay wrote:
> I have a mod_perl-2 handler that uses custom_response() to display error
> messages if something goes wrong:
> 
> $r->custom_response(Apache2::Const::SERVER_ERROR, $error);
> return Apache2::Const::SERVER_ERROR;
> 
> That almost works fine, but the trouble is that the Content-Type header
> is always set to "text/html; charset=iso-8859-1", in which the charset,
> at least, is potentially wrong: all the pages in my software produce
> UTF-8 and are normally output with Content-Type "application/xhtml+xml;
> charset=utf-8".
> 
> How do I set the Content-Type when issuing a custom_reponse()? The usual
> thing of calling
> 
> $r->content_type("application/xhtml+xml; charset=utf-8");
> 
> doesn't seem to work in this case.
> 
I think that is impossible. ap_send_error_response() contains this code:

        if (apr_table_get(r->subprocess_env,
                          "suppress-error-charset") != NULL) {
            core_request_config *request_conf =
                        ap_get_module_config(r->request_config, &core_module);
            request_conf->suppress_charset = 1; /* avoid adding default
                                                 * charset later
                                                 */
            ap_set_content_type(r, "text/html");
        }
        else {
            ap_set_content_type(r, "text/html; charset=iso-8859-1");
        }

The resulting content-type is either "text/html; charset=iso-8859-1" or 
"text/html".

But instead of passing the response text directly to $r->custom_response you 
can specify an URL. ap_die() will then create an internal redirect to this 
URL. Via $r->prev->pnotes you can then access the pnotes of the failed 
request. Putting all together a solution could look like:

  $r->pnotes->{estring}=$error;
  $r->pnotes->{ect}='my/special-content-type';
  # use an otherwise not used URL here
  $r->custom_response(Apache2::Const::SERVER_ERROR, '/-/error');

  <Location /-/error>
    SetHandler modperl
    # please insert a \ at the end of each of the following lines 
    # up to }"
    PerlResponseHandler "sub {
      my ($r)=@_;
      return Apache2::Const::NOT_FOUND unless $r->prev;
      $r->content_type($r->prev->pnotes->{ect});
      $r->print($r->prev->pnotes->{estring});
      return Apache2::Const::OK;
    }"
  </Location>

Torsten Förtsch

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