Question

I have some content types (nodes) that are attached to various taxonomies. For specific node types, I want to do some validation on the taxonomy. I do not want to hard-code the nodes types and their corresponding fields that reference the taxonomy. So I put them in array.

However, I am unable to dereference the field names. I’ve tried double $$, quotes, etc, but can’t get it to work. Is what I want to do possible?

Below is a standalone PHP that I am trying to get to work.

<?php

$node = (object) array(
    'nid' => NULL,
    'vid' => NULL,
    'uid' => '1',
    'type' => 'price_document',
    'language' => 'und',
    'field_taxonomy_price' => array(
        'und' => array(
            array(
                'tid' => '94'
            )
        )
    ),
);


  $nodes_to_check = array("price_document" => "field_taxonomy_price",
                          "package"        => "field_taxonomy_package",
                         );



  if (array_key_exists($node->type,$nodes_to_check)) {
    $taxonomy_field = $nodes_to_check[$node->type];
    print_r($taxonomy_field);
    $tid = $node->field_taxonomy_price ['und'][0]['tid']; //  <- this works but, how
    //$tid = $node->"$$taxonomy_field" ['und'][0]['tid'];     <- can I deref variable?
  }
?>

Answer 1

Well, you can do this:

 $taxonomy_field = $nodes_to_check[$node->type];
 $tid = $node->{$taxonomy_field}['und'][0]['tid];

You don’t need the double dollar signs. That’s in case you want to do things like this:

 $dog = "I am a dog";
 $var = "dog";
 $$var = "Now I'm a pussycat";
 echo $dog; // Output: Now I'm a pussycat