Magento 1.9 – Fix Uncaught Error: Call to a Member Function addData() on Boolean

I am new to Magento and trying to build a module. in my module, I have created a custom databse table which is successfully added to database now I want to add some data to the database table and I am getting following error.

Fatal error</b>:  Uncaught Error: Call to a member function addData() on boolean in E:\xampp\htdocs\magento4\app\code\local\Wri\TodoHelper\controllers\IndexController.php:19
Stack trace:
#0 E:\xampp\htdocs\magento4\app\code\core\Mage\Core\Controller\Varien\Action.php(418): Wri_TodoHelper_IndexController-&gt;sayHelloAction()
#1 E:\xampp\htdocs\magento4\app\code\core\Mage\Core\Controller\Varien\Router\Standard.php(254): Mage_Core_Controller_Varien_Action-&gt;dispatch('sayHello')
#2 E:\xampp\htdocs\magento4\app\code\core\Mage\Core\Controller\Varien\Front.php(172): Mage_Core_Controller_Varien_Router_Standard-&gt;match(Object(Mage_Core_Controller_Request_Http))
#3 E:\xampp\htdocs\magento4\app\code\core\Mage\Core\Model\App.php(365): Mage_Core_Controller_Varien_Front-&gt;dispatch()
#4 E:\xampp\htdocs\magento4\app\Mage.php(683): Mage_Core_Model_App-&gt;run(Array)
#5 E:\xampp\htdocs\magento4\index.php(83): Mage::run('', 'store')
#6 {main}
  thrown in <b>E:\xampp\htdocs\magento4\app\code\local\Wri\TodoHelper\controllers\IndexController.php</b> on line <b>19</b><br />

config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Wri_TodoHelper>
            <version>1.0.0</version>
        </Wri_TodoHelper>
    </modules>
    <global>
        <helpers>
            <wri_todohelper>
                <class>Wri_TodoHelper_Helper</class>
            </wri_todohelper>
        </helpers>
        <models>
            <wri_todohelper>
                <class>Wri_TodoHelper_Model</class>
                <resourceModel>wri_todohelper_resource</resourceModel>
            </wri_todohelper>

            <wri_todohelper_resource>
                <class>Wri_TodoHelper_Model_Resource</class>
                <entities>
                    <todo> <!-- define an new  entities for module -->
                        <table>wri_todohelper_lists</table> <!-- define table -->
                    </todo>
                </entities>
            </wri_todohelper_resource>
        </models>
        <blocks>
            <wri_todohelper>
                <class>Wri_TodoHelper_Block</class>
            </wri_todohelper>
        </blocks>
        <resources>
            <wri_todohelper_setup>
                <setup>
                    <module>Wri_TodoHelper</module>
                </setup>
            </wri_todohelper_setup>
        </resources>
    </global>
    <frontend>
        <routers>
            <Wri_TodoHelper_SayHello>
                <use>standard</use>
                <args>
                    <module>Wri_TodoHelper</module>
                    <frontName>todo</frontName>
                </args>
            </Wri_TodoHelper_SayHello>
        </routers>
        <layout>
            <updates>
                <custommodule>
                    <file>todohelper.xml</file>
                </custommodule>
            </updates>
        </layout>
    </frontend>
</config>

install-1.0.0.php

$tableName = $installer->getTable('wri_todohelper/todo');
if (!$connection->isTableExists($tableName)){
    $table = $connection
        ->newTable($tableName)
        ->addColumn(
            'id',
            Varien_Db_Ddl_Table::TYPE_INTEGER,
            null,
            array(
                'identity' => true,
                'unsigned' => true,
                'nullable' => false,
                'primary'  => true,
            ),
            'ID'
        )
        ->addColumn(
            'task',
            Varien_Db_Ddl_Table::TYPE_VARCHAR,
            255,
            array(
                'nullable' => false,
            ),
            'Task Name'
        )->addColumn(
            'status',
            Varien_Db_Ddl_Table::TYPE_INTEGER,
            10,
            array(
                'nullable' => false,
            ),
            'Task Staus'
        ) ->addColumn(
            'created_at',
            Varien_Db_Ddl_Table::TYPE_DATETIME,
            null,
            array(
                'nullable' => false,
            ),
            'Created At'
        );
    $connection->createTable($table);
}

$installer->endSetup();

Todo.php
root/app/code/local/Wri/TodoHelper/Model/

<?php
class Wri_TodoHelper_Model_TodoHelper extends Mage_Core_Model_Abstract
{
    public function _construct()
    {
        $this->_init('wri_todohelper/todo');
    }

}

TodoHelper.php
root/app/code/local/Wri/TodoHelper/Model/Resource

    <?php

class Wri_TodoHelper_Model_Resource_TodoHelper extends Mage_Core_Model_Resource_Db_Abstract
{
    /**
     * Initialize resource model
     *
     * @return void
     */
    public function _construct()
    {
        $this->_init('wri_todohelper/todo', 'id');
    }
}

?>

Collection.php
root/app/code/local/Wri/TodoHelper/Model/Resource/TodoHelper

<?php

class Wri_TodoHelper_Model_Resource_TodoHelper_Collection
    extends Mage_Core_Model_Resource_Db_Collection_Abstract{
    protected function _construct(){
        parent::_construct();
        $this->_init('wri_todohelper/todo');
    }
}

IndexController.php

<?php

class Wri_TodoHelper_IndexController extends Mage_Core_Controller_Front_Action
{
    public function indexAction()
    {
        echo 'Hello developer...';
    }

    public function sayHelloAction()
    {
        $taskname = $_REQUEST['todo'];
        $status = $_REQUEST['todo'];

        $response = '';

        if ($taskname && $status){
            $data = array('task'=>$taskname, 'status'=> $status);
            $model = Mage::getModel('wri_todohelper/todo')->addData($data);
            try {
                $model->save(); //save data
                $insertId = $model->getId();
                $response->status = "success";
                $response->data = "Data successfully inserted. Insert ID: " . $insertId;
                echo $response;
            } catch (Exception $e) {
                $response->status = "failed";
                $response->data = $e->getMessage();
                echo $response;
            }
        }else{
            $response->status = "failed";
            $response->data = "Not Found";
            echo $response;
        }
    }
}

?>

Please Help !!!