How can I pass the loop.index from a view template to a node template?

Question

In a views template (views-view-unformatted.twig.html), I have

{% for row in rows %}  
    {% set row_index = loop.index0 %}  
    {{ row.content }}  
{% endfor %}  

where each row is processed in a node--view.twig.html. How can I pass in row_index to the node--view.twig.html? This is used simply to create an index.

Answer 1

This can be done using the preprocess function in my_theme.theme. In the case above, the row was formatted in node--view--pagename.html.twig, so the preprocessor function name is mytheme_preprocess_node__view__pagename. In the function, the view is iterated until the node matches the current node that is being processed, at that point, the row_index is determined and set and accessible in node--view--pagename.html.twig as {{ row_index }}.

function fu_preprocess_node__view__pagename(&$vars) {
    $view = $vars['view'];
    $node = $vars['node'];
    foreach($view->result as $key => $row){
        if($row->nid == $node->id()){
            $vars['row_index'] = $row->index;
        }
    }
}