GetUserOption function is defined in Project Data Model class:
class Project extends CActiveRecord
{
/**
 * @return string the associated database table name
 */
public function tableName()
{
	return 'tbl_project';
}
/**
 * @return array validation rules for model attributes.
 */
public function rules()
{
	// NOTE: you should only define rules for those attributes that
	// will receive user inputs.
	return array(
		array('name, description', 'required'),
		array('create_user_id, update_user_id', 'numerical', 'integerOnly'=>true),
		array('name', 'length', 'max'=>255),
		array('create_time, update_time', 'safe'),
		// The following rule is used by search().
		// @todo Please remove those attributes that should not be searched.
		array('id, name, description, create_time, create_user_id, update_time, update_user_id', 'safe', 'on'=>'search'),
	);
}
/**
 * @return array relational rules.
 */
public function relations()
{
    return array(
        'issues' => array(self::HAS_MANY, 'Issue', 'project_id'),
        'users' => array(self::MANY_MANY, 'User', 'tbl_project_user_assignment(project_id, user_id)'),
    );
}
/**
 * @return array customized attribute labels (name=>label)
 */
public function attributeLabels()
{
	return array(
		'id' => 'ID',
		'name' => 'Name',
		'description' => 'Description',
		'create_time' => 'Create Time',
		'create_user_id' => 'Create User',
		'update_time' => 'Update Time',
		'update_user_id' => 'Update User',
	);
}
/**
 * Retrieves a list of models based on the current search/filter conditions.
 *
 * Typical usecase:
 * - Initialize the model fields with values from filter form.
 * - Execute this method to get CActiveDataProvider instance which will filter
 * models according to data in model fields.
 * - Pass data provider to CGridView, CListView or any similar widget.
 *
 * @return CActiveDataProvider the data provider that can return the models
 * based on the search/filter conditions.
 */
public function search()
{
	// @todo Please modify the following code to remove attributes that should not be searched.
	$criteria=new CDbCriteria;
	$criteria->compare('id',$this->id);
	$criteria->compare('name',$this->name,true);
	$criteria->compare('description',$this->description,true);
	$criteria->compare('create_time',$this->create_time,true);
	$criteria->compare('create_user_id',$this->create_user_id);
	$criteria->compare('update_time',$this->update_time,true);
	$criteria->compare('update_user_id',$this->update_user_id);
	return new CActiveDataProvider($this, array(
		'criteria'=>$criteria,
	));
}
/**
 * Returns the static model of the specified AR class.
 * Please note that you should have this exact method in all your CActiveRecord descendants!
 * @param string $className active record class name.
 * @return Project the static model class
 */
public static function model($className=__CLASS__)
{
	return parent::model($className);
}
/**
* @return array of valid users for this project, indexed by user IDs
*/
public function getUserOptions()
{
    $usersArray = CHtml::listData($this->users, 'id', 'username');
    return $usersArray;
}
}
and it is used in issue creation form as:
<div class="row">
	<?php echo $form->labelEx($model,'owner_id'); ?>
	<?php echo $form->dropDownList($model,'owner_id', $model->project->getUserOptions()); ?>
	<?php echo $form->error($model,'owner_id'); ?>
</div>
<div class="row">
	<?php echo $form->labelEx($model,'requester_id'); ?>
	<?php echo $form->dropDownList($model,'requester_id', $model->project->getUserOptions()); ?>
	<?php echo $form->error($model,'requester_id'); ?>
</div>
Its giving error:
Fatal error: Call to a member function getUserOptions() on null in C:\xampp\htdocs\trackstar\protected\views\issue\_form.php on line 48
How can we acess project user names from issue controller or issue model classes, I don’t have any idea.