Programmatically adding columns in VIEWS - drupal

Question

In drupal 7 view, I have created a custom module and add dynamic columns using below method.
function my_module_views_pre_view(&$view, &$display_id, &$args) {
if ($view->name == 'my_view') {
$countries = my_module_vocab_terms('countries');
foreach ($countries as $country){
$view->add_item($view->current_display, 'field', 'views', 'nothing', array(
'label' => $country->name,
'alter' => array('text' => $country->tid),
'element_class' => 'my-field',
'element_default_classes' => 0,
), $country->tid);
}
}
}
}
But the text value repeated in each rows like this.
Please suggest how to pass value for each row.
Thanks

Answer 1

If anyone is still interested how to alter values to such fields.
You can do so by rendering the fields and altering the data in one of the hooks where the results are already fetched eg. the hook_views_post_execute, hook_views_pre_render, hook_views_post_render depending on your needs.
/**
* Implements hook_views_post_execute().
*/
function my_module_views_post_execute(view &$view) {
$view->style_plugin->render_fields($view->result);
$view_fields = &$view->style_plugin->rendered_fields;
foreach ($view_fields as &$field) {
$field['my_field'] = "some value";
}
unset($field);
}