Symfony2 - 如何在实体字段或树枝布局中实现嵌套记录和递归函数？

Question

I have a serious doubt about doing a combo box with nested records from an entity in Symfony2. I have read about nested tree extension for Doctrine 2 in http://gediminasm.org/article/tree-nestedset-behavior-extension-for-doctrine-2, it appears to be interesting but it does not refer how to implementing this nested tree into an entity field in a form.

Also, I have read more about recursive functions in PHP, and I have found an interesting blog where it is analyzed, here is the link http://www.sitepoint.com/hierarchical-data-database/, it explains specifically about this recursive function:

function display_children($parent, $level) {

    // Retrieve all children of $parent
    $result = mysql_query('SELECT title FROM tree WHERE parent="'.$parent.'"');

    // Display each child
    while ($row = mysql_fetch_array($result)) { 

        // Indent and display the title of this child
        echo str_repeat('  ',$level).$row['title']."
";

        // Call this function again to display this child's children
        display_children($row['title'], $level+1);
    }
}

Somebody knows how to translate this code into Symfony2 and where it would be stored (Controller, Entity, etc.). If someone has other ideas about working nested records with Twig Extensions, It would be appreciate too.

Thanks a lot your help.

Answer 1

You can have a look to this tree implementation that is not based on nested sets but on materialzed paths: https://github.com/KnpLabs/materialized-path .

You could imagine use its API to get a flat resultset of the tree, like in your code snippet:

$root = $repo->find($id);
$repo->buildTree($root);

$flatArray = $root->toFlatArray(function(NodeInterface $node) {
    $pre = $node->getLevel() > 1 ? implode('', array_fill(0, $node->getLevel(), '--')) : '';
    return $pre.(string)$node;
});

return $this->get('templating')->render('::tree.html.twig', $flatArray);