插入在codeigniter中无法正常工作

I am trying to insert data into the database and my code does add a new row but all the values are null. I don't know what's causing it. The view is inside a modal in html. Here's my code: Thanks for your help

Controller:

public function addItem(){
    $save = array(
        'inventoryID' => $this->input->post('rfid'),
        'masterCode' => $this->input->post('masterCode'),
        'itemName' => $this->input->post('itemName'),
        'colorName' => $this->input->post('colorName'),
        'location' => $this->input->post('location'),
        'itemCategory' => $this->input->post('itemCategory'),
        'materialDescription' => $this->input->post('materialDescription'),
        'supplier' => $this->input->post('supplier'),
        'itemDescription' => $this->input->post('itemDescription'),
        'comments' => $this->input->post('comments'),
        'itemCode' => $this->input->post('itemCode'),
        'colorCode' => $this->input->post('colorCode')
    );
    $this->searchModel->form_insert($save);

    //load the header
    $this->load->view('base.php',$save);
    //load the page
    redirect('Search');
    //load the footer
    $this->load->view('footer.php',$save);
}

Model:

function form_insert($data){

    // Inserting in Table(inventory) of Database(library)
    $this->load->database();
    $this->db->insert('inventory', $data);
    $inventoryID = $this->db->insert_id();
}

View:

<div id="addItem" class="modal fade">
  <div class="modal-dialog">
    <div class="modal-content">
      <form method ="post" action= "<?php echo site_url("Search/addItem"); ?>">
        <div class="modal-header">
          <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
          <h4 class="modal-title">Add an Item</h4>
        </div>
        <div class="modal-body">
          <form role="form">
            <table>
              <tr>
                <td><input type="text" name="rfid" placeholder="RFID" required/></td>
                <td><input type="text" name="itemCode" placeholder="Item Code" required/></td>
                <td><input type="text" name="masterCode" placeholder="Master Code" /></td>
              </tr>
              <tr>
                <td><input type="text" name="itemName" placeholder="Item Name" required/></td>
                <td><input type="text" name="colorCode" placeholder="Color Code" /></td>
                <td><input type="text" name="colorName" placeholder="Color Name" /></td>
              </tr>
              <tr>
                <td><input type="text" name="location" placeholder="Location" required/></td>
                <td><input type="text" name="makelocation" placeholder="Location Made" required/></td>
                <td><input type="text" name="itemCategory" placeholder="Item Category" /></td>
              </tr>
              <tr>
                <td><input type="text" name="materialDescription" placeholder="Material Description" /></td>
                <td><input type="text" name="supplier" placeholder="Supplier/Vendor" required/></td>
                <td><input type="text" name="checkoutAllowed" placeholder="Checkout Allowed" /></td>
              </tr>
            </table>
            <div class="row personal-info">
              <div class="col-sm-4">
                <div class="form-group">
                  <textarea name="itemDescription" placeholder="Insert information regarding the weather this item is suitable for and where it is used"></textarea>
                  <textarea name="Comments" placeholder="Additional Coments on the Item"></textarea>
                </div>
              </div>
            </div>
          </form>
        </div>
        <div class="modal-footer" style="text-align:center;">
          <a href="<?php echo site_url("Search/addItem") ?>"><input class="btn btn-primary" name="addItem" value="Add Item"></a>
        </div>
      </form>
    </div>
  </div>
</div>

The problem is that you do not actually "submit" the form data. Your button links to the correct controller/method but does not send any data to the controller when you use a link, i.e. <a href=.... You need a submit button.

The change is quite simple. Change the code for the button as follows.

<div class="modal-footer" style="text-align:center;">
  <input type="submit" class="btn btn-primary" name="addItem" value="Add Item">
</div>

There is another issue. You have two <form> tags. Remove the line

<form method ="post" action="<?php echo site_url("Search/addItem"); ?>">

And change the line

<form role="form">

to

<form method="post" action="<?php echo site_url("Search/addItem"); ?>" role="form">

You also need to remove the extra form close tag two lines above the button's code. Nested <form>s are not allowed. And you need to move the closing tag for <div class="modal-content"> So to make it more clear here is what your view should finally look like.

<div id="addItem" class="modal fade">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
        <h4 class="modal-title">Add an Item</h4>
      </div>
      <div class="modal-body">
        <form method ="post" action= "<?php echo site_url("Search/addItem"); ?>" role="form">
          <table>
            <tr>
              <td><input type="text" name="rfid" placeholder="RFID" required/></td>
              <td><input type="text" name="itemCode" placeholder="Item Code" required/></td>
              <td><input type="text" name="masterCode" placeholder="Master Code" /></td>
            </tr>
            <tr>
              <td><input type="text" name="itemName" placeholder="Item Name" required/></td>
              <td><input type="text" name="colorCode" placeholder="Color Code" /></td>
              <td><input type="text" name="colorName" placeholder="Color Name" /></td>
            </tr>
            <tr>
              <td><input type="text" name="location" placeholder="Location" required/></td>
              <td><input type="text" name="makelocation" placeholder="Location Made" required/></td>
              <td><input type="text" name="itemCategory" placeholder="Item Category" /></td>
            </tr>
            <tr>
              <td><input type="text" name="materialDescription" placeholder="Material Description" /></td>
              <td><input type="text" name="supplier" placeholder="Supplier/Vendor" required/></td>
              <td><input type="text" name="checkoutAllowed" placeholder="Checkout Allowed" /></td>
            </tr>
          </table>
          <div class="row personal-info">
            <div class="col-sm-4">
              <div class="form-group">
                <textarea name="itemDescription" placeholder="Insert information regarding the weather this item is suitable for and where it is used"></textarea>
                <textarea name="Comments" placeholder="Additional Coments on the Item"></textarea>
              </div>
            </div>
          </div>
          <div class="modal-footer" style="text-align:center;">
            <input type="submit" class="btn btn-primary" name="addItem" value="Add Item">
          </div>
        </form>
      </div>
    </div>
  </div>
</div>