Trying to render a custom date format with Twig

Question

I'm in the process of porting one of my contrib themes to Drupal 8. For custom date formats on nodes, I have something like this in a node_preprocess function in the theme's template.php file in the Drupal 7 version:

$vars['thedate'] = format_date($node->created, "custom", "j");
$vars['themonth'] = format_date($node->created, "custom", "M");
$vars['theyear'] = format_date($node->created, "custom", "Y");

I render it with the following code.

  <?php print $thedate; ?> / <?php print $themonth; ?> / <?php print $theyear; ?>

In my Drupal 8 port, I've tried a similar approach in the theme's .theme file and then try to render them in node.html.twig as {{{ thedate }} / {{ themonth }} / {{ theyear }}}, but I'm getting a nasty error.

Twig_Error_Runtime: An exception has been thrown during the rendering of a template ("The timestamp must be numeric.") in themes/mytheme/templates/page.html.twig at line 210. in Twig_Template->displayWithErrorHandling() (line 279 of /site/core/vendor/twig/twig/lib/Twig/Template.php).

I looked to Twig date formats, and it seems you should simply attach a variable, such as {{ display_submitted |date("m/d/Y") }}. I tried that without a preprocess function but what outputs is 12/31/1969, which is not the date the node was created so I'm a bit lost here.

Answer 1

$node->created is a FieldItemList object.

You need to use either one of these.

$vars['thedate'] = format_date($node->created->value, "custom", "j");
$vars['thedate'] = format_date($node->getCreatedTime(), "custom", "j");

All node base fields (and most other entity types, some are still being worked on) have methods now, that are defined in NodeInterface.

Answer 2

Here is an approach that uses just Twig (no preprocess functions needed):

<p>{{ node.createdtime | date("d F Y") }}</p>

Answer 3

For people who need a little more help understanding this, add the following to YOURTHEMENAME.theme file:

/**
 * Implements template_preprocess_comment()
 */
function YOURTHEMENAME_preprocess_comment(&$variables) {
  $comment = $variables['elements']['#comment'];
  $variables['YOUR_DATE_NAME'] = format_date($comment->created->value, "custom", "m / j / y");
}

Then in your theme, update the twig template (such as templates/comment.html.twig) to use the variable like so: {{ YOUR_DATE_NAME }}