Say the user is creating a node. I want to display a drop down option list, with prepopulated options, based on a calculation (i.e. reference to user's groups, user's other nodes, etc...). Drupal 7.

I've had no luck with the rules, computed field, prepopulate field modules... maybe i'm missing something?

3 Answers 3


Use hook_form_alter or hook_form_FORM_ID_alter to pre-populate your dropdown list with results returned from a custom function.

For example, using a form of hook_form_alter():

$form['field_my_field']['und']['#options'] = _my_custom_function();

Then make sure your function _my_custom_function() return's a proper array.

function _my_custom_function() {
    $custom_values = array();
    $custom_values['key1'] = 'value1';
    $custom_values['key2'] = 'value2';
    $custom_values['key3'] = 'value3';
    return $custom_values;

Obviously you can include some 'logic' in the _my_custom_function() to return your calculated list.

Here are a few super-useful link's I wish I would have know about before.


write a module and provide a hook_form_alter to change the values of the form element. Just google hook_form_alter for tutorials and code snippets.


Are you using a list field?

It has support for a callback to provide the allowed values. See list_field_info() That is however not exposed in the UI (which makes somewhat sense as you can't implement a function there either).

So you can simply implement a function that returns the allowed values and then update the field configuration (through api calls in your module, directly in the database, or export your field as a feature and then adjust it there).

In fact, if it is a list field, you probably have to do it this way instead of a hook_form_alter() in order to get past the validation, but I'm not 100% sure.

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