我决定把验证和消息放在HunterModel.php模型中，我的createHunter()方法在HunterController.php文件中应该插入一条记录。
下面的代码片段显示了我遇到的问题：显然，$this->$data->listError();并没有揭示我在$validationMessages中定义的消息。

• HunterModel.php

// Validation
    protected $validationRules      = [
        'name_hunter' => 'required|max_length[30]',
        'age_hunter' => 'required|integer',
        'height_hunter' => 'required|decimal',
        'weight_hunter' => 'required|decimal',
        'type_hunter' => 'required|max_length[30]',
        'type_nen' => 'required|max_length[30]',
        'type_blood' => 'required|max_length[3]'
    ];
    protected $validationMessages   = [
        'name_hunter' => [
            'required' => 'Hunter name cannot be empty.',
            'max_length' => 'The hunter name must have a maximum of 30 characters.'
        ],
        'age_hunter' => [
            'required' => 'Hunter age cannot be empty.',
            'integer' => 'The hunter's age must be an integer.'
        ],
        'height_hunter' => [
            'required' => 'Hunter height cannot be empty.',
            'decimal' => 'The hunter height must be a decimal number.'
        ],
        'weight_hunter' => [
            'required' => 'Hunter weight cannot be empty.',
            'decimal' => 'The hunter weight must be a decimal number.'
        ],
        'type_hunter' => [
            'required' => 'It is necessary to define the type of hunter.',
            'max_length' => 'The hunter type must be a maximum of 30 characters.'
        ],
        'type_nen' => [
            'required' => 'It is necessary to define the nen of the hunter.',
            'max_length' => 'The hunter's nen must have a maximum of 30 characters.'
        ],
        'type_blood' => [
            'required' => 'It is necessary to define the hunter's blood type.',
            'max_length' => 'The hunter's blood type must be a maximum of 3 characters.'
        ]
    ];

• HunterController.php

public function createHunter()
    {
        try {
            $hunter = new HunterModel();
            $data = [
                'name_hunter' => $this->request->getPost('name_hunter'),
                'age_hunter' => $this->request->getPost('age_hunter'),
                'height_hunter' => $this->request->getPost('height_hunter'),
                'weight_hunter' => $this->request->getPost('weight_hunter'),
                'type_hunter' => $this->request->getPost('type_hunter'),
                'type_nen' => $this->request->getPost('type_nen'),
                'type_blood' => $this->request->getPost('type_blood')
            ];
            if ($hunter->insert($data)){
                return $this->response->redirect(site_url('/read_hunters'));
            } else {
                $this->$data->listError();
            }
        } catch (\Exception $e) {
            exit($e->getMessage());
        } 
    }