Add Entity Label field (Was: allow entity ref fields to point to data items)

Selecting a data item from somewhere else with entity reference probably won't work yet. The main thing is probably the absence of a label callback...

See #1551430: implement hook_entity_property_info for Feeds integration

I've added a label to hook_entity_property_info() which may help.

I suspect it's rather the label callback in hook_entity_info() that we need, but that would need checking.

Yup, it uses entity_label(): http://api.drupal.org/api/drupal/includes!common.inc/function/entity_lab...

Hence we need a label key or callback.

Thank joachim. Feeds integration is something I'm keen to get working and I've noticed data_entity lacks a few required methods and properties. The label shouldn't be too hard to add.

Looking at entity_data.module's hook_entity_info(), the label is currently set to the table's title. ['entity keys']['label'] is not set.

Those are two different things.

$info[label] is the label of the entities as a whole, like 'Node'.
$info['entity keys']['label'] is the key on the entity that gives you the label for that entity, so like 'About us' for a page node.

In the case of a data entity, I imagine $info['entity keys']['label'] would the primary key(s). Except the primary key field is used as the entity ID, which needs to be an integer, so that wouldn't be very friendly. This could be combined with the table name or label.

This may be a rare case: my primary key field is an auto-increment integer field which isn't included when saving the entity.

Ideally, the primary key(s) could be independent of the entity ID, with a separate config option to specify the entity ID field.

Alternatively, data_entity could set and increment the ID specific to each entity type.

Ok, to the topic at hand: could the label be 1 or more fields selected on the "Configure Entity Form"? Does it need to be unique?

Added a label callback which uses index fields as the label. Multiple indexes are separated by a space in the label.

Updated status.

+++ b/data_entity/data_entity.module
@@ -192,6 +193,22 @@ function data_entity_permission() {
+  if (isset($schema['indexes'])) {

This will return NULL if there aren't any indexes, which may cause problems with other modules expecting a string.

Should we return something like '' or 'No label'?

Alternatively, we could add checkboxes to the data table management UI to pick which columns to make up labels.

"No label" sounds good.

This adds the option to the Entity Configuration form.

Some notes:

1. The schema is used to get the fields in their correct order. This may be important for label fields but if it isn't we could just loop through the meta information.

2. The callback looks a bit clumsy getting all the information. There may be a cleaner way.

3. Unrelated to this issue: theme_data_entity_admin_entity_form() sticks an extra blank cell at the end of each row. Is this necessary?

+++ b/data_entity/data_entity.module
@@ -173,6 +175,22 @@ function data_entity_permission() {
+function data_entity_label($entity, $entity_type) {
+  $table = DataTable::instance($entity->data_table);
+  $meta = $table->get('meta');
+  $schema = drupal_get_schema($entity->data_table);
+  $labels = array();
+  foreach ($schema['fields'] as $field_name => $field) {
+    if ($meta['fields'][$field_name]['label_field']) {
+      $labels[] = $entity->$field_name;
+    }
+  }

I don't think you need to get the schema here. Just iterate over $meta['fields'] and see if there are labels set.

Alternatively, perhaps in the submit handler for data_entity_admin_entity_form() we could save a nice piece of metadata that specifically gives us a list of the label fields, so we don't need to muck about with looping every time.

Also, does DataTable::instance() cache anything? If not, we should possibly investigate performance of this, say in an entity reference field.

Finally, I've just thought of something -- how does the autocomplete widget for entref work? Is it compatible with a label callback that builds the label programmatically, or does it only work with a particular entity property being the label? If that's the case, we should probably limit just one column to being the label.

The schema reflects the order of the fields in the admin screens, $meta['fields'] doesn't. That said, a list of label fields as separate metadata sounds like a nicer way to go.

I'm not sure about autocomplete, I'll have to check.

What alternatives are there to DataTable::instance()? All we really need is the metadata, can Data module provide this alone?

> What alternatives are there to DataTable::instance()? All we really need is the metadata, can Data module provide this alone?

Oh I'm fairly sure we need this, as it's the way into the Data API. My concern is that if you're looking at a dropdown of entities, creating that class and having it load the same thing from the database once for each entity in the dropdown is going to be quite expensive. I'd like that to be statically cached somewhere.

Multiple label fields may be overkill. If we only had one we could potentially avoid a label callback, although we'd need a helper function for hook_entity_info(). Does this cache its information?

Yup, hook_entity_info() is cached. Doing expensive things in that is fine, though beware of circularity there.

Here's a much simpler approach which allows one column to be selected as the label. If one isn't specified a callback is used so it doesn't break anything.

Looks good. Would be great if someone could try it out!

Updated title. Hopefully we can get some action here.

Been struggling with this all day. Hoped that the patch would cure it. Still not able to display anything at all for the referenced data. Is anybody able to make this work, or is it just me?

Hard to know. This patch does add the entity label as described, but there may be other issues.

What modules and what patches are you using?

The patch at #20 was nearly there -- just wasn't saving the setting in the UI.

Here's an update patch.

Committed. New alpha release shortly!

Thanks to everyone who's worked on this.

SHA: 9865f0c0ca4c70701fe8a9d977f535beedfcb53c
Author: imclean
Subject: Issue #1538588 by imclean, joachim: Added setting for field to use for entity label, thus allowing use of data entities as targets for entityreference fields.