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copied!<p>I'm not sure why you'd want to expressly avoid using a plugin or a CPAN module - any solution you come up with will likely do the the same things as a plugin and/or CPAN module except that since it's new code it won't be as mature and tested.</p> <p>I've recently started using Dancer to develop a simple app and I'll describe how I'm solving this problem using CPAN modules. You may of course choose to ignore it.</p> <p>My route handler for adding a user looks like this:</p> <pre><code>post '/user/add' => { my $args = valid_input('/user/add') or return template('user/add'); my $user = User->new({ username => $args->{username}, # ... }); user->insert; # you'll probably want some error handling here set_flash('User added'); redirect '/user'; }; </code></pre> <p>The <code>valid_input</code> function is a helper I created for my app, which uses the <a href="https://metacpan.org/release/Data-FormValidator" rel="nofollow">Data::Form::Validator</a> module from CPAN. The <code>'/usr/add'</code> argument is the name of the validation profile to use - which for simplicity I decided to keep the same as the route name.</p> <p>I won't bore you with the details of calling <a href="https://metacpan.org/release/Data-FormValidator" rel="nofollow">Data::Form::Validator</a> since the documentation is pretty good. What I will mention is that in the event that validation fails, the <code>valid_input</code> helper stores away the validation error messages for display in an alert box and also saves the submitted parameters:</p> <pre><code>my $q = params(); # need to force scalar context to get a hashref; fill_in_form($q); # save submitted parameters </code></pre> <p>I have a <code>before_template_render</code> hook that makes the saved validation error messages available to the template (they actually get rendered in <code>views/layouts/main.tt</code>).</p> <p>I also have an <code>after_template_render</code> hook that takes the saved submitted parameters and puts them back into the rendered HTML form using the <a href="https://metacpan.org/release/HTML-FillInForm" rel="nofollow">HTML::FillInForm</a> module.</p> <p>Since I have that infrastructure in place, the route handler to display an existing user record in an edit form with all the fields pre-populated is trivial:</p> <pre><code>get '/user/:id' => sub { if( my $user = User->find( param('id') ) ) { fill_in_form($user); return template 'user/edit', { id => $user->id }; } not_found "User not found"; }; </code></pre> <p>The <code>User</code> in <code>User->find()</code> is another one of my app-specific helper functions. It uses the <a href="https://metacpan.org/release/Dancer-Plugin-DBIC" rel="nofollow">Dancer::Plugin::DBIC</a> module to return a resultset object for my <code>user</code> table.</p> <p>I will say that I'm not necessarily a huge fan of Data::Form::Validator. I have been able to achieve everything I wanted but sometimes it does seem to take more work than I'd like.</p>

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