$c->flash Not Dereferencing Data Objects

[phildeman]

Hi All,

I encountered something unusual with Perl 5.14.2.

I am using DBIx::Class to query my database. The data object is returned to Root to be passed to a View.
I pass the data object to the View via $c->flash. However, in the View it has a problem dereferencing the
data object.

For example, I query a person's name and address and store it in bio_object. Then I pass it to $c->flash like so:

In Root.pm:

 my $bio_obj = $model->get_bio_info( $id );
 $c->flash->{ 'bio' } = $bio_obj;
 $c->res-redirect( 'myviewpage' );

In myviewpage, using Mason in HTML page:

   <p>My name is <% $bio->name %><br />
   My residence is at <% $bio->address %>

   
<%init>
my $bio = $c->flash->{ 'bio' } if $c->flash->{ 'bio' };
</%init>

The view error message states it cannot find the method 'name' or 'address'. However, I created a test script
that calls the same query method, "get_bio_info". I display the results without issues, using a print statement.

Has anyone experienced this before?

[Your Mother]

I don’t have time to write test code but I think see the problem. You can only use a flash entry once. It’s gone—removed from the session—after that. The entire point is it cannot persist past a single use. Put it in the stash instead—unless you need it to persist past a redirect or something—and you should be fine. And just to be clear, this is actually a Catalyst question, not a DBIx::Class question. The flash/stash is part of the Catalyst context and its session.

More detail, when you do if $c->flash->{bio}, you just used it so it’s gone by the time you get to the assignment. Also note, you should never put a conditional on an (update: variable declarative) assignment statement. It can behave strangely.

# Unpredictable-
my $x = 1 if $y;
# Safe-
my $x;
$x = 1 if $y;

Update in case you do need it as flash, untested–

<%init>
my $bio = $c->flash->{'bio'};
</%init>

% if ( $bio ) {
   <p>My name is <% $bio->name |h %><br />
   My residence is at <% $bio->address |h %></p>
% }

Update, added HTML escape filters. Been ages since I did Mason. :P NEVER trust user input.