Drupal 7 Form API, Checkboxes with key -> value from database

Question

I'm working on a custom module and I'm adding a form that uses checkboxes. All is fine with using code like:

$form['tags'] = array( '#type' => 'checkboxes', '#options' => array( 88 => 'option1', 100 => 'option 2', 79 => 'etc' ), '#title' => t('Tag this project as...'), );

The problem comes from the fact that I'd like to pull the key and value from the database (a specific taxonomy). I do not want to use an autocomplete, I want to use checkboxes.

Specifically, how do I get the results from the database and format into a proper array for the options array? Also, on the edit version of the form I'm creating, how do I show items that have been "checked" based on their value?

All of the examples I've seen are extremely basic and never show how to do this from a database call. Thanks for reading/answering

Answer 1

To populate your options array with data from table my_table, with value keys from column value and text from column atext, you can use:

$options = array();
$result = db_select('my_table', 'mt')
            ->fields('mt', array('value', 'atext'))
            ->execute();
foreach ($result as $row) {
  $options[$row->value] = $row->atext;
}

To get taxonomy terms, you could use the code above to query tid and name from the taxonomy_term_data table (plus add a condition() for the vocabulary id), but for this specific usage you'd better to use the right API:

$options = array();
// Get term tree for vocabulary which id is in $vid.
$terms = taxonomy_get_tree($vid);
foreach ($terms as $term) {
  $options[$term->tid] = $term->name;
}

Just do not forget that vocabularies are tree structures. See the documentation for the taxonomy_get_tree() API to know how to limit the terms you want to get from a vocabulary wrt starting term and tree depth.