A PHP Error was encountered, A Database Error Occurred

My Models: models: Stock_m.php

<?php defined('BASEPATH') OR exit('No direct script access allowed');

class Stock_m extends CI_Model {

    public function add_stock_in($post)
    {
        $params = [
            'item_id' => $post['item_id'],
            'type' => ['in'],
            'detail' => $post['detail'],
            'supplier_id' => $post['supplier'] == '' ? null :  $post['supplier'],
            'qty' => $post['qty'],
            'date' => $post['date'],
            'user_id' => $this->session->userdata('userid'),

        ];
        $this->db->insert('t_stock', $params);

    }

}

My controllers: controllerts/Stock.php

<?php defined('BASEPATH') OR exit('No direct script access allowed');

class Stock  extends CI_Controller {

    function __construct()
    {
        parent::__construct();
        check_not_login();
        check_admin();
        $this->load->model(['item_m', 'supplier_m', 'stock_m']);
    }

    public function stock_in_data() {
        $this->template->load('template', 'transaction/stock_in/stock_in_data');
    }
    public function stock_in_add() {
        $item = $this->item_m->get()->result();
        $supplier = $this->supplier_m->get()->result();
        $data = ['item' => $item, 'supplier' => $supplier];
        $this->template->load('template', 'transaction/stock_in/stock_in_form', $data);
    }

    public function process() {
        if(isset($_POST['in_add'])) {
            $post = $this->input->post(null, TRUE);
            $this->stock_m->add_stock_in($post);
            $this->item_m->update_stock_in($post);

            if($this->db->affected_rows() > 0) {
                $this->session->set_flashdata('success', 'Data Stock-In berhasil disimpan');
            }
            redirect('stock/in');
        }
    }

}

My view: transaction/stock_in/stock_in_form.php

<section class="content-header">
      <h1>Stock In
        <small>Barang Masuk / Pembelian</small>
      </h1>
      <ol class="breadcrumb">
        <li><a href="#"><i class="fa fa-dashboard"></i></a></li>
        <li>Transaction</li>
        <li><a href="#"></a></li>
        <li class="active">Stock In</li>
      </ol>
    </section>

    <!-- Main content -->
    <section class="content">

    <div class="box">
        <div class="box-header">
            <h3 class="box-title">Add Stock In</h3>
            <div class="pull-right">
                <a href="<?=site_url('stock/in')?>" class="btn btn-warning btn-flat">
                   <i class="fa fa-undo"></i> Back
                </a>
            </div>
         </div>
         <div class="box-body">
            <div class="row">
                <div class="col-md-4 col-md-offset-4">
                    <form action="<?=site_url('stock/process')?>" method="post">
                        <div class="form-group">
                            <label>Date *</label>
                            <input type="date" name="date" value="<?=date('Y-m-d')?>" class="form-control" required>
                        </div>
                        <div>
                            <label for="barcode">Barcode *</label>
                        </div>
                        <div class="form-group input-group">
                            <input type="hidden" name="item_id" id="item_id">
                            <input type="text" name="barcode" id="barcode" class="form-control" required autofocus>
                            <span class="input-group-btn">
                                <button type="button" class="btn btn-info btn-flat" data-toggle="modal" data-target="#modal-item">
                                    <i class="fa fa-search"></i>
                                </button>
                            </span>
                        </div>
                        <div class="form-group">
                            <label>Item Name *</label>
                            <input type="text" name="item_name" id="item_name" class="form-control" readonly>
                        </div>
                        <div class="form-group">
                            <div class="row">
                                <div class="col-md-8">
                                    <label for="unit_name">Item Unit</label>
                                    <input type="text" name="unit_name" id="unit_name" value="-" class="form-control" readonly>
                                </div>
                                <div class="col-md-4">
                                    <label for="stock">Initial Stock</label>
                                    <input type="text" name="stock" id="stock" value="-" class="form-control" readonly>
                                </div>
                            </div>
                        </div>
                        <div class="form-group">
                            <label>Detail *</label>
                            <input type="text" name="detail" class="form-control" placeholder="Tambahan / etc" required>
                        </div>
                        <div class="form-group">
                            <label>Supplier</label>
                            <select name="supplier" class="form-control">
                                <option value="">- Pilih -</option>
                                <?php foreach($supplier as $i =>$data) {
                                    echo '<option value="'.$data->supplier_id.'">'.$data->name.'</option>';
                                } ?>
                            </select>
                        </div>
                        <div class="form-group">
                            <label>Qty *</label>
                            <input type="number" name="qty" class="form-control" required>
                        </div>

                        <div class="form-group">
                            <button type="submit" name="in_add" class="btn btn-success btn-flat">
                               <i class="fa fa-paper-plane"></i> Save
                            </button>
                            <button type="Reset" class="btn btn-flat">Reset</button>
                        </div>
                    </form>
                </div>
            </div>
         </div>
    </div>

</section>

<div class="modal fade" id="modal-item">
    <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data.dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">&times;</span>
                </button>
                <h4 class="modal-title">Select Product Item</h4>
            </div>
            <div class="modal-body table-responsive">
                <table class="table table-bordered table-striped" id="table1">
                    <thead>
                        <tr>
                            <th>Barcode</th>
                            <th>Name</th>
                            <th>Unit</th>
                            <th>Price</th>
                            <th>Stock</th>
                            <th>Actions</th>
                        </tr>
                    </thead>
                    <tbody>
                        <?php foreach($item as $i => $data) { ?>
                        <tr>
                            <td><?=$data->barcode?></td>
                            <td><?=$data->name?></td>
                            <td><?=$data->unit_name?></td>
                            <td class="text-right"><?=indo_currency($data->price)?></td>
                            <td class="text-right"><?=$data->stock?></td>
                            <td class="text-right">
                                <button class="btn btn-xs btn-info" id="select"
                                    data-id="<?=$data->item_id?>"
                                    data-barcode="<?=$data->barcode?>"
                                    data-name="<?=$data->name?>"
                                    data-unit="<?=$data->unit_name?>"
                                    data-stock="<?=$data->stock?>">
                                    <i class="fa fa-check"></i> Select
                                </button>
                            </td>
                        </tr>
                        <?php } ?>
                    </tbody>
                </table>
            </div>
        </div>
    </div>
</div>

<script>
    $(document).ready(function() {
        $(document).on('click', '#select', function(){
            var item_id = $(this).data('id');
            var barcode = $(this).data('barcode');
            var name = $(this).data('name');
            var unit_name = $(this).data('unit');
            var stock = $(this).data('stock');
            $('#item_id').val(item_id);
            $('#barcode').val(barcode);
            $('#item_name').val(name);
            $('#unit_name').val(unit_name);
            $('#stock').val(stock);
            $('#model-item').modal('hide');
        })
    })

</script>

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