Populating #options, #header for tableselect in ajax callback function - drupal-7

Question

What I am trying to do is display a table with checkboxes on the press of a button by ajax. The table should be initially hidden and get populated on the fly by a function call.
If initially I load $options1 with some dummy values , then after ajax call it throws in an error saying-
Notice: Undefined index: red in theme_tableselect() (line 3285 of
D:\wamp\www\drupal7\includes\form.inc).
where 'red' is the index of a dummy row value and #options don't get populated with the new values. What is the way to get this working ?
Here is the code for the form-
$form['mltag_new']['tag'] = array(
'#type' => 'button',
'#value' => t("Suggest Tags"),
'#ajax' => array(
'callback' => 'mltag_suggest_tags_ajax',
'wrapper' => 'mltag_suggest_tags_table_div',
'effect' => 'slide',
),
);
$options1 = array(); //initial dummy values
$options1['red']['tag'] = "A red row";
$options1['red']['chi'] = "A red row";
$form['mltag_new']['myselector'] = array (
'#type' => 'tableselect',
'#title' => 'My Selector',
'#header' => $header,
'#options' => $options1,
'#prefix' => '<div id="mltag_suggest_tags_table_div">',
'#suffix' => '</div>',
);
return $form;
and the Ajax callback looks something like this-
function mltag_suggest_tags_ajax($form, $form_state) {
//$content has some content
//pass the content to a function
include_once 'includes/content_tag.inc';
$tags = mltag_content_tag($content, variable_get('algo_type'), 20);
if (empty($tags)) {
$output .= t('Content is insufficient to generate Tags using this algorithm. <br>Please choose other algorithm from Settings Page.');
$form['mltag_new']['sample_text']['#markup'] = $output;
return $form['mltag_new']['sample_text'];
}
else {
$algo = variable_get('algo_type');
if ($algo == 1) {
$header = array(
'tag' => t('Tag'),
'frequency' => t('Frequency'),
);
$options = array();
foreach ($tags as $key => $value) {
$options[$key] = array(
'tag' => $key,
'frequency' => $value,
);
}
}
elseif ($algo == 2) {
$header = array(
'tag' => t('Tag'),
'chi' => t('Chi Square Value'),
);
$options = array();
foreach ($tags as $key => $value) {
$options[$key] = array(
'tag' => $key,
'chi' => $value,
);
}
}
$form['mltag_new']['myselector']['#header'] = $header;
$form['mltag_new']['myselector']['#options'] = $options;
return $form['mltag_new']['myselector'];
}
}

Answer 1

I replied to your post on Drupal.org about how I'm working on a somewhat similar problem. Try adding
$form['mltag_new']['myselector'] =
form_process_tableselect($form['mltag_new']['myselector']);
just before your return. Hopefully that helps you more than it did me. Beware that the #options just get rendered when the block reloads from the ajax, but the original $form object doesn't seem to be aware.

Answer 2

I know that this is a few years later, but I found this while searching for my own solution:
The tableselect module creates checkboxes in the $ form that have to be removed. in the example above, they would be in $form['mltag_new']['myselector'] with keys equal to the original $option1 in your original code. If you unset those, then call
$form['mltag_new']['myselector'] = form_process_tableselect($form['mltag_new']['myselector']);
before your return, it will eliminate the dummy rows.