Not able to get form element's value after submitting form using this.form.submit();

Question

Here's my HTML with PHP:

<form method="post" action="">
    <select name="seltemplate" id="seltemplate" style="width:150px" onChange="this.form.submit();">
        <option value="0">Select a Template</option>
        <?php
        // Running the sql query
        $query = "SELECT * FROM `stripo_email_templates`";
        $rs = mysqli_query($con, $query);

        // If at least one record found
        if(mysqli_num_rows($rs) > 0)
        {
            // Fetch table rows
            while($row = mysqli_fetch_array($rs))
            {
                $template_id = $row['template_id'];
                $template_name = $row['template_name'];
                echo "<option value='$template_id'>$template_name</option>";
            }
        }
        ?>
    </select>
</form>

I am submitting form using this.form.submit(); without any submit button.

So as soon as select list option is changed, the form is submitted.

After submission of form, I want to receive value of select list selected option.

I am echoing

echo $_POST['seltemplate'];

but no value is received. Why?

Answer 1

this.form.submit() is not good practice to write in select box element because "this" means select box not form or document for that you try this code.

function select_box_change()
{
    var f = document.getElementById('form1');
    f.action = "your_php_file";
    f.submit();
}

html

<form method="post" id="form1">
    <select id="seltemplate" style="width:150px" onChange="select_box_change();">
        <option value="0">Select a Template</option>
        <option>a</option>
        <option>b</option>
    </select>
</form>