Prevent duplicate entry in Codeigniter

How to prevent duplicate entry in codeigniter? Following is the code:-

$params = array('value1' => 'test_value', 'value2' => 'test_value');
$this->db->insert('table_name',$params);

2 ways to prevent duplicate entry insertion into the database,

METHOD 1

You can use $this->form_validation->set_rules in the controller file and you can validate your input values,

Example :

In Controller

$this->form_validation->set_rules('value1', 'value1 field label', 'trim|required|xss_clean|is_unique[table_name.value1]');
$this->form_validation->set_rules('value2', 'value2 field label', 'trim|required|xss_clean|is_unique[table_name.value2]');
$this->form_validation->set_message('is_unique', '%s is already exists');
if ($this->form_validation->run() === TRUE){
    // load your model function here
    $this->model_name->insert();
}

In Model

public function insert(){
    $postdata = $this->input->post();  
    extract($postdata);
    $this->db->insert('table_name', compact('value1','value2'));
    return ($this->db->trans_status()) ? $this->db->insert_id() : false;
}

METHOD 2

Validating values in model file before insert

$params = array('value1' => 'test_value', 'value2' => 'test_value');
extract($postdata);
if($this->db->limit(1)->get_where('table_name', compact('value1'))->num_rows() === 0 && $this->db->limit(1)->get_where('table_name', compact('value2'))->num_rows() === 0){
    $this->db->insert('table_name', $params);
}
return ($this->db->trans_status()) ? $this->db->insert_id() : false;