Ajax JQuery post code with Php to query MySql database not working

I have an HTML form that runs a Javascript function on page load. In the Javascript function, a town name is sent via Ajax post call to Php function to get details from MySql database.

Ajax call in JavaScript function

var town = "Town name";          //depends on the previous execution in JS function
if (town != "undefined") {
    jQuery.ajax({
        type: "POST",
        url: '../model/data_access/GetCity.php',
        dataType: 'json',
        data: {town: town},
        success: function (obj) {
            document.getElementById("selectedLocation").value = obj[0]["name"];
            document.getElementById("placeDescriptionBox").value = obj[0]["description"];
        }
    });
}

GetCity.php

$town = $_POST['town'];
get_city($town);

function get_city($town)
{
    $place = array();
    $db_conn = DBConnection::get_database_connection(); 
    $stmt = $db_conn->prepare("SELECT * FROM place WHERE name=?");
    $stmt->bind_param("s", $town);
    $stmt->execute();

    if (!($result = $stmt->get_result())) {
        echo "Error" . $stmt->error;
    }

    if ($result->num_rows > 0) {
        $row = $result->fetch_assoc();
        $place[0] = new Place();
        $place[0]->set_name($row["name"]);
        $place[0]->set_description($row["description"]);
        echo json_encode($place);
    }
}

The data from database are not displayed in the HTML form. How can I solve this? I'm new to Ajax JQuery so any help is much appreciated.

Copyright License：
Author:「Fleur」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/37342687/ajax-jquery-post-code-with-php-to-query-mysql-database-not-working