Dropdown select onChange redirect to url with a parameter in CodeIgniter

Question

How I would access this url index.php/backend/categories/get_categories/$id within a <select> dropdown onChange ?

I mean, if I will go to index.php/backend/categories/get_categories/1, it will output a table with all categories under component id 1.

What I want, is once i select an option from a dropdown list, i want it to submit and redirect to the same url, but with a specific ID from <option val="$id"> ?

To generate a dropdown list with CodeIgniter FORM helper:

<?php
    echo form_open('backend/categories/get_categories');
    $selectComponentData = array(0 => '-- '.lang('SELECT_COMPONENTS').' --');
    $selectComponentJs = 'onChange="this.form.submit()" id="selectCatsByComponent"';

    foreach($selectComponents as $option){
        $selectComponentData[$option->id] = $option->name;
    }
    echo form_dropdown('selectCatsByComponent', $selectComponentData, 0, $selectComponentJs);
    echo form_close();
?>

And output HTML is:

<form accept-charset="utf-8" method="post" action="http://127.0.0.1/backend/web/index.php/backend/categories/get_categories">
    <select id="selectCatsByComponent" onchange="this.form.submit()" name="selectCatsByComponent">
        <option selected="selected" value="0">-- Choose a component --</option>
        <option value="1">E-commerce</option>
        <option value="2">Content</option>
    </select>
</form>

How to make it possible ?

Solution

if I dont get you wrong, You are asking something like this;

In controller;

public function get_categories()
{
    if(isset($_POST) && !empty($_POST())
    {

        $id = $this->input->post('selectCatsByComponent');

        // bla bla bla

        $data['id'] = $id;
        $this->load->view('whatever/whatever',$data);
    }
    else
    {
        //Your normal page before posting
    }
}

Now you can access the id value in view like this

if(isset($id)) // if there is a $id loaded
{
    // Your view accoring to $id
}

Note: I did not have an test environment while I was writing this code. So The code is not complate and there might be some mistakes