我想使用form_dropdown（...）填充下拉列表中的名称列表，并相应地获取匹配的名称。
我的模型和控制器类似乎都工作正常，但是我无法将第二个参数传递给视图中的form_dropdown（）函数，并得到错误消息“Undefined variable：分支”，我试着转储getBranch（）返回的值，它工作了。我有3个不同的PHP脚本用于视图：“index”（显示表单表等中的数据），“form”（我在这里为一个新学生填写详细信息）和“index-datatable”（数据表的Jquery脚本）。请注意，所有视图都在一个目录/文件夹“students”中，如控制器的索引函数所示。我是Codeigniter 3的新手。

控制器类

public function __construct() {
        parent::__construct();
        is_login();
        $this->load->library('form_validation');
        $this->load->helper(array('form', 'url'));
        $this->load->database();
        $this->load->model('menu_model', 'menu');
        $this->load->model('my_model', 'my');
        $this->load->model('students_model', 'students');
    
    }

    public function index() {
        $data['branch'] = $this->students->getBranch(); //Get the names of branches. 

        $data['title'] = 'Student List Home';

        $data['page'] = 'students/index';
      
        $data['datatable'] = 'students/index-datatable';

        $this->load->view('back/layouts/main', $data);
  
    }

模型类

function getBranch() {
        $this->db->select('id');
        $this->db->select('name');
        $this->db->from('branch');        
        
        $query = $this->db->get();
        $result = $query->result();

        $branch_id = array('-CHOOSE-');
        $branch_name = array('-CHOOSE-');

        for ($i = 0; $i < count($result); $i++) {
            array_push($branch_id, $result[$i]->id);
            array_push($branch_name, $result[$i]->name);
        }
        return $branch_result = array_combine($branch_id, $branch_name);
        
    }

视图（窗体，非索引）

<div class="form-group">
                    <label for="branch">Branch</label>
                    <?php
                    $attributes = 'class = "form-control" id = "branch"';
                    echo form_dropdown('branch', $branch, set_value('branch'), $attributes);
                    
                    ?>
                </div>

添加方法

public function add() {
        if (!$_POST) {
            $input = (object) $this->students->getDefaultValues();
        } else {
            $input = (object) $this->input->post(null, true);
        }

        $this->form_validation->set_rules('package_name', 'Title', 'required', [
            'required' => 'Text can not be empty'
                ]
        );
        $this->form_validation->set_rules('package_fee', 'Text', 'required', [
            'required' => 'Text can not be empty'
                ]
        );

        $this->form_validation->set_rules('duration', 'Text', 'required', [
            'required' => 'Text can not be empty'
                ]
        );

        $this->form_validation->set_rules('category_id', 'Text', 'required', [
            'required' => 'Text can not be empty'
                ]
        );

        if ($this->form_validation->run() == false) {
            $data['title'] = 'Register a new Student';
            $data['page'] = 'students/form';
            $data['form_action'] = base_url("students/add");
            $data['input'] = $input;
            $this->load->view('back/layouts/main', $data);
        } else {

            $data = [
                'title' => $this->input->post('title', true),
                'firstname' => $this->input->post('firstname', true),
                'lastname' => $this->input->post('lastname', true),
                'othername' => $this->input->post('othername', true),
                'gender' => $this->input->post('gender', true),
                'dob' => $this->input->post('dob', true),
                'nationality' => $this->input->post('nationality', true),
                'address' => $this->input->post('address', true),
                'email' => $this->input->post('email', true),
                'phone_number' => $this->input->post('phone_number', true),
                'education' => $this->input->post('education', true),
                'occupation' => $this->input->post('occupation', true),
                'nationalidtype' => $this->input->post('nationalidtype', true),
                'id_number' => $this->input->post('id_number', true),
                'prev_driving_exp' => $this->input->post('prev_driving_exp', true),
                'photo' => $this->input->post('photo', true),
                'license_type_id' => $this->input->post('license_type_id', true),
                'branch_id' => $this->input->post('branch_id', true),
                'group_id' => $this->input->post('group_id', true)
            ];

            if (!empty($_FILES['photo']['name'])) {
                $upload = $this->students->uploadImage();
                $data['photo'] = $upload;
            }

            $this->students->insert($data);
            $this->session->set_flashdata('success', 'Student Data added successfully');

            redirect(base_url('students'));
        }
    }

***主视图***仅显示加载其他页面的位置。一些脚本被删除，即页眉和页脚脚本。

<div id="wrapper">

            <?php $this->load->view('back/layouts/_sidebar') ?>


            <div id="content-wrapper" class="d-flex flex-column">

                <div id="content">

                    <nav class="navbar navbar-expand navbar-light bg-white topbar mb-4 static-top shadow">

                        <button id="sidebarToggleTop" class="btn btn-link d-md-none rounded-circle mr-3">
                            <i class="fa fa-bars"></i>
                        </button>

                        <?php $this->load->view('back/layouts/_topbar') ?>
                    </nav>

                    <?php $this->load->view('back/pages/' . $page) ?>

                </div>

                <?php $this->load->view('back/layouts/_footer') ?>

            </div>

        </div>