Trouble passing errors back to form through setRouteVariables

Question

This has me a bit stumped.

I have two forms - posting to two different actions within the same controller. On error I am attempting to have them both display a flash-notice, as well as pass the model back to my template so that I can display the errors to the user.

This works as intended for one of my forms/actions, but not for the other - well, that is, the flash-message works for both, but for the latter form/action model is undefined in my template.

Some examples (I've stripped out some code to not clutter the question):

Working action

public function actionCreateArtist()
{
  $this->requirePostRequest();
  $request = craft()->request->getPost();
  $model   = new CoverApp_ArtistModel();
  $model->setAttributes($request);
  if ($model->validate() && craft()->coverApp_data->createArtist($model)) {
    craft()->userSession->setNotice('Artist created.');
    $this->redirectToPostedUrl();
  }
  craft()->userSession->setError('Unable to create artist');
  craft()->urlManager->setRouteVariables(array('model' => $model));
}

Working form

<form method="POST" class="styled-form">
  {{ getCsrfInput() }}
  <input type="hidden" name="action" value="coverApp/data/createArtist">
  <input type="hidden" name="redirect" value="coverapp/record-company/{{ companyId }}">
  <input type="submit" value="Create artist">
</form>
{{ model is defined ? 'Yes' : 'No' }}
{% set error = craft.session.getFlash('error', false, false) %}
{% if error and model is defined %}
  <div>
    <ul>
      {% for errorType in model.getErrors() %}
        {% for error in errorType %}
          <li>- {{ error }}</li>
        {% endfor %}
      {% endfor %}
    </ul>
  </div>
{% endif %}

The example above outputs "Yes" and any errors that happened during validation/save, per-example name already taken.

Action I am struggling with

public function actionCreateRecordCompany()
{
  $this->requirePostRequest();
  $request = craft()->request->getPost();
  $model   = new CoverApp_RecordCompanyModel();
  $model->setAttributes($request);
  if ($model->validate() && craft()->coverApp_data->createRecordCompany($model)) {
    craft()->userSession->setNotice('Record company created.');
    $this->redirectToPostedUrl();
  }
  craft()->userSession->setError('Unable to create record-company');
  craft()->urlManager->setRouteVariables(array('model' => $model));
}

Form I am struggling with

<form method="POST" class="styled-form">
  {{ getCsrfInput() }}
  <input type="hidden" name="action" value="coverApp/data/createRecordCompany">
  <input type="hidden" name="redirect" value="coverapp">
  <input type="submit" value="Create record-company">
</form>
{{ model is defined ? 'Yes' : 'No' }}
{% set error = craft.session.getFlash('error', false, false) %}
{% if error and model is defined %}
  <div>
    <ul>
      {% for errorType in model.getErrors() %}
        {% for error in errorType %}
          <li>- {{ error }}</li>
        {% endfor %}
      {% endfor %}
    </ul>
  </div>
{% endif %}

The above outputs 'No' and none of the errors that happened during validation/save, per example name already taken.

To further obfuscate the problem, if I have no errors during validation/save everything works peachy - which at least leads me to believe that my models are fine.

Any ideas?

Update 31/10/2016

registerCpRoutes

public function registerCpRoutes()
{
  return array('coverapp/record-company/create' => array('action' => 'coverApp_Rendering/renderCreateRecordCompany'),
  'coverapp/record-company/(?P<companyId>[\d]+)/createArtist' => array('action' => 'coverApp_Rendering/renderCreateArtist'));
}

rendering-controller

public function actionRenderCreateRecordCompany()
{
  $this->renderPluginTemplate('coverapp/recordCompanyCreate');
}

public function actionRenderCreateArtist(array $variables = array())
{
  $this->renderPluginTemplate('coverapp/artistCreate', $variables);
}

private function renderPluginTemplate($template, $variables = array())
{
  $oldMode = craft()->templates->getTemplateMode();
  craft()->templates->setTemplateMode(TemplateMode::Site);
  if (!$templatePath = craft()->templates->findTemplate($template)) {
    throw new Exception(Craft::t('Could not find template with path: ' . $template));
  }
  else {
    $templateContent   = file_get_contents($templatePath);
    $templateExtension = IOHelper::getExtension($templatePath, 'html');
  }
  craft()->templates->setTemplateMode($oldMode);
  if ($output = craft()->templates->renderString($templateContent, $variables)) {
    if (!HeaderHelper::isHeaderSet('Content-Type')) {
      HeaderHelper::setContentTypeByExtension($templateExtension);
    }
    HeaderHelper::setHeader(array('charset' => 'utf-8'));
    if (in_array(HeaderHelper::getMimeType(), array('text/html', 'application/xhtml+xml'))) {
      $headHtml = craft()->templates->getHeadHtml();
      $footHtml = craft()->templates->getFootHtml();
      if ($headHtml) {
        if (($endHeadPos = mb_stripos($output, '</head>')) !== FALSE) {
          $output = mb_substr($output, 0, $endHeadPos) . $headHtml . mb_substr($output, $endHeadPos);
        }
        else {
          $output .= $headHtml;
        }
      }
      if ($footHtml) {
        if (($endBodyPos = mb_stripos($output, '</body>')) !== FALSE) {
          $output = mb_substr($output, 0, $endBodyPos) . $footHtml . mb_substr($output, $endBodyPos);
        }
        else {
          $output .= $footHtml;
        }
      }
    }
    ob_start();
      echo $output;
      craft()->end();
    }
}

Answer 1

So, it turns out (as is often the case) that posting the problem makes you look at it in a fresh light, and as such I found my own solution.

What I needed to do (leaving this here in case someone else has a similar problem and come looking for help) was to make the following change to my rendering-controller:

old

public function actionRenderCreateRecordCompany()
{
  $this->renderPluginTemplate('coverapp/recordCompanyCreate');
}

new

public function actionRenderCreateRecordCompany(array &variables = array())
{
  $this->renderPluginTemplate('coverapp/recordCompanyCreate');
}

I guess this makes sense - I didn't include it originally as my route never passed any variables to it - but of course when I use setRouteVariables in my controller-action I need something on the receiving end to catch it.