Saving a value from a drop down to a variable PHP - php

Question

I am trying to save the value selected in the date drop down box to a variable '$AvailabilityID' which is retrieved on the next page. The drop down box is populated from the MYSQL table bs_availability. From what I've read I need to use Javascript but really no idea how to do it.
Any help appreciated.
<?php
//current URL of the Page. cart_update.php redirects back to this URL
$current_url = base64_encode("http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']);
$results = $mysqli->query("SELECT SessionType, SessionName, SessionCost, SessionID FROM bs_session
GROUP BY SessionName ORDER BY SessionType ASC;");
if ($results) {
//output results from database
while($obj = $results->fetch_object())
{
$availabilityresults = $mysqli->query("SELECT * From bs_availability WHERE sessionID = ".$obj->SessionID.";");
echo '<tr>';
echo '<form method="post" action="cart_update.php">';
echo '<td>'.$obj->SessionName.'</td>';
echo '<td>'.$obj->SessionType.'</td>';
echo '<td><select name="date">';
//While loop to populate drop down with table data
while($objdate = $availabilityresults->fetch_object())
{
echo '<option value ="'.$objdate->AvailabilityID.'">'.$objdate->Date.'</option>';
}
echo '</select>';
echo '</td>';
echo '<td>Price '.$currency.$obj->SessionCost.' <button class="add_to_cart">Add To Cart</button></td>';
echo '</tr>';
echo '<input type="hidden" name="SessionID" value="'.$obj->SessionID.'" />';
echo '<input type="hidden" name="AvailabilityID" value="'.$objdate->AvailabilityID.'" />';
echo '<input type="hidden" name="type" value="add" />';
echo '<input type="hidden" name="return_url" value="'.$current_url.'" />';
echo '</form>';
echo '</div>';
}
}
?>
EDIT: This code is the cart_update.php. So when Add to Basket is pressed this script is run using the $SessionID from the selected item but I also need the AvailabiltyID of the chosen date so that I can run the right query to add the right date to the basket.
<?php
session_start(); //start session
include_once("config.php"); //include config file
//empty cart by distroying current session
if(isset($_GET["emptycart"]) && $_GET["emptycart"]==1)
{
$return_url = base64_decode($_GET["return_url"]); //return url
session_destroy();
header('Location:'.$return_url);
}
//add item in shopping cart
if(isset($_POST["type"]) && $_POST["type"]=='add')
{
$SessionID = filter_var($_POST["SessionID"], FILTER_SANITIZE_STRING); //product code
$AvailabilityID = filter_var($_POST["AvailabilityID"], FILTER_SANITIZE_STRING); //product code
$product_qty = filter_var($_POST["product_qty"], FILTER_SANITIZE_NUMBER_INT); //product code
$return_url = base64_decode($_POST["return_url"]); //return url
//limit quantity for single product
if($product_qty > 10){
die('<div align="center">This demo does not allowed more than 10 quantity!<br />Back To Products.</div>');
}
console.log($availabilityID);
//MySqli query - get details of item from db using product code
$results = $mysqli->query("SELECT SessionName, SessionCost FROM bs_session WHERE SessionID=$SessionID LIMIT 1");
//$results = $mysqli->query("SELECT bs_session.SessionName, bs_availability.Date, bs_session.SessionCost FROM bs_availability INNER JOIN bs_session ON bs_session.SessionID=bs_availability.SessionID WHERE bs_availability.AvailabilityID=$AvailabilityID LIMIT 1");
$obj = $results->fetch_object();
if ($results) { //we have the product info
//prepare array for the session variable
$new_product = array(array('name'=>$obj->SessionName, 'code'=>$SessionID, 'date'=>$obj->Date, 'price'=>$obj->SessionCost));
if(isset($_SESSION["products"])) //if we have the session
{
$found = false; //set found item to false
foreach ($_SESSION["products"] as $cart_itm) //loop through session array
{
if($cart_itm["code"] == $SessionID){ //the item exist in array
$product[] = array('name'=>$cart_itm["name"], 'code'=>$cart_itm["code"], 'date'=>$cart_itm["date"], 'price'=>$cart_itm["price"]);
$found = true;
}else{
//item doesn't exist in the list, just retrive old info and prepare array for session var
$product[] = array('name'=>$cart_itm["name"], 'code'=>$cart_itm["code"], 'date'=>$cart_itm["date"], 'price'=>$cart_itm["price"]);
}
}
if($found == false) //we didn't find item in array
{
//add new user item in array
$_SESSION["products"] = array_merge($product, $new_product);
}else{
//found user item in array list, and increased the quantity
$_SESSION["products"] = $product;
}
}else{
//create a new session var if does not exist
$_SESSION["products"] = $new_product;
}
}
//redirect back to original page
header('Location:'.$return_url);
}
//remove item from shopping cart
if(isset($_GET["removep"]) && isset($_GET["return_url"]) && isset($_SESSION["products"]))
{
$SessionID = $_GET["removep"]; //get the product code to remove
$return_url = base64_decode($_GET["return_url"]); //get return url
foreach ($_SESSION["products"] as $cart_itm) //loop through session array var
{
if($cart_itm["code"]!=$SessionID){ //item does,t exist in the list
$product[] = array('name'=>$cart_itm["name"], 'code'=>$cart_itm["code"], 'qty'=>$cart_itm["qty"], 'price'=>$cart_itm["price"]);
}
//create a new product list for cart
$_SESSION["products"] = $product;
}
//redirect back to original page
header('Location:'.$return_url);
}

Answer 1

In PHP, this is done through the POST array on your cart_update.php page:
if (isset($_POST['date'])){
$AvailabilityID = $_POST['date'];
}
You could also change the existing add to cart button to give it a name that will appear in the POST array:
echo '<td>Price '.$currency.$obj->SessionCost.' <button class="add_to_cart" name="add_to_cart">Add To Cart</button></td>';
This is often used as a check on the processing page, with an if block around all of the processing code.
if (isset($_POST['add_to_cart'])){
//all processing code here
}

Answer 2

Just use the POST Variable $_POST['date'] which holds the selected option value.