Allow modules to bypass taxonomy_get_tree() for term reference select lists

this is pretty much required when dealing with large vocabs.

+1

Hmm, actually a field setting should be declared with a default value (empty string ?) in hook_field_info().

Yup :-)

Actually, is this sufficient? We are seeing linear slowdown when creating thousands of terms. I think that taxonomy_field_validate() actually uses the full allowed values list and computing these allowed values gets more and more expensive as term count increases. We need to fix allowed values as in the OP or not use it in validation.

Upgrading priority as this is not just a UI fail anymore

re #10 : whether the new setting should restrict the list of valid values depends on the feature catch is after, I guess ?

Regarding the performance cost of taxonomy_field_validate() calling taxonomy_allowed_values() calling taxonomy_get_tree() : we had similar problems in nodereference some time ago. We solved it by deferring the validate check to a helper function, accepting an optional array of candidate nids as param; the contract then becomes "filter invalid values out of the list I'm giving you, plz", which is more manageable performance-wise.

See _node_reference_potential_references_standard(), and how it's called in node_reference_options_list(), node_reference_field_validate(), node_reference_autocomplete()

I guess a similar approach could be used for taxo terms ? Might be a separate issue than the use case described in the OP, though.

Hmm. My slowdown must be caused by something else. This one is back to RTBC.

+++ modules/taxonomy/taxonomy.module	4 Mar 2010 12:16:50 -0000
@@ -1094,7 +1095,14 @@ function taxonomy_field_widget_info_alte
 function taxonomy_options_list($field) {
-  return taxonomy_allowed_values($field);
+  if (!empty($field['settings']['options_list_callback'])) {
+    $function = $field['settings']['options_list_callback'];
+    $options = $function($field);
+  }
+  else {
+    $options = taxonomy_allowed_values($field);
+  }
+  return $options;

This looks rather hacky to me. Why not always force the callback to be set explicitly?

re catch #12 : oopsie, you're right, I was on crack.

Feld API does support default values for settings, whether field, instance, widget or formatter settings.

re #15-16 : that's a choice of semantics.
I think the current choice of '' as a default value, with a semantic of 'this will use the dafault : taxonomy_allowed_values()' is more future proof (allows later renaming or refactoring without needing to change the existing $field settings).

Maybe a slight code refactor of

$function = !empty($field['settings']['options_list_callback']) ? $field['settings']['options_list_callback'] : 'taxonomy_allowed_values';
$options = $function($field);

?
Matter of taste, really.

RTBC again.

Related issue - #556842: taxonomy_get_tree() memory issues

Dries, does that last patch address your comments? I personally find a bunchofcodecrammedononelinewithaternaryoperatorincrediblyhardtoread.

Alrighty then. Committed to CVS HEAD.

Follow-up bug in #1281732: Fatal error when taxonomy_options_list() tries to call an undefined callback function.