在codeigniter中使用select multiple的内容填充PHP数组

In my view I have a form select multiple box where I add items using a select dropdown and a button like this.

This is how the code of the select multiple box looks after adding 3 items to it.

<label for="nombresFamilia" class="col-md-4 control-label"></label>
<div class="col-md-6">
   <select multiple id="nombresFamilia" name="nombresFamilia[]" class="form-control">
       <option value="CABLES">CABLES</option>
       <option value="PCR">PCR</option>
       <option value="POSTES">POSTES</option>
   </select>
</div>

After submitting the form information, I want to save the items inside the select multiple into an array. This is the code I have in my controller.

function add()
{   
    .
    .
    .
    $this->form_validation->set_rules('nombresFamilia[]','NombresFamilia');

    if($this->form_validation->run())     
    {   
        .
        .
        .

        $params_familia = $this->input->post('nombresFamilia[]');  
    }
}

However, when I try to var_dump the array

<?php
    echo "<pre>";
    var_dump($params_familia);
    echo "</pre>";
?>

I get the message: "Undefined variable: params_familia".

What am I doing wrong?

you could pre-select the options of the select, do something like this
VIEW

<select name="nombresFamilia[]" class="" multiple="multiple">
  <option value="CABLES" selected="selected">CABLES</option>
  <option value="PCR" selected="selected">PCR</option>
  <option value="POSTES" selected="selected">POSTES</option>
</select>

CONTROLLER

$nombresFamilia = $this->input->post('nombresFamilia');
// remove [] in nombresFamilia

echo "<pre>";
var_dump($params_familia);
echo "</pre>";

PRODUCES

Array
(
    [0] => CABLES
    [1] => PCR
    [2] => POSTES
)

Checkboxes are named as arrays, dropdowns are not named as arrays . In Drop down or < select > only one value is returned which is selected. if you want to get value of the selected item. Name your select element as

<select multiple id="nombresFamilia" name="nombresFamilia" class="form-control">
   <option value="CABLES">CABLES</option>
   <option value="PCR">PCR</option>
   <option value="POSTES">POSTES</option>
</select>

and then get the value as

$params_familia = $this->input->post('nombresFamilia'); 

if you want multiple selections then create checkboxes instead of dropdown as

<input type="checkbox" name="nombresFamilia[]" value="CABLES">Cables
<input type="checkbox" name="nombresFamilia[]" value="PCR">PCR
<input type="checkbox" name="nombresFamilia[]" value="POSTES">POSTES

and then get the values in your controller as

$params_familia = $this->input->post('nombresFamilia[]');  

Edit as Per comment

If you want to send all the values to the post , create array of checkboxes like

<input type="checkbox" name="nombresFamilia[]" value="CABLES" selected>Cables
<input type="checkbox" name="nombresFamilia[]" value="PCR" selected>PCR
<input type="checkbox" name="nombresFamilia[]" value="POSTES" selected>POSTES

and then post. In your Controller get these values by

$params_familia = $this->input->post('nombresFamilia[]');  

You can use the form helper's multiselect function in your view like this in:

$options = array(
              'small'  => 'Small Shirt',
              'med'    => 'Medium Shirt',
              'large'   => 'Large Shirt',
              'xlarge' => 'Extra Large Shirt',
            );

echo form_multiselect('shirts[]', $options);

And then in controller, use the array like this:

print_r($this->input->post('shirts[]'));

Hope this helps.