PHP、MySQL - 将复选框与下拉菜单关联

Question

I'm having an issue with trying to add a "quantity" to a product that a person is ordering. I've got a Products table, an orders table, an order_item table (which is a many-to-many table that contains the id's from both products and orders). I've got a dropdown box on the left which has the quantity that you want. The maximum value is the stock available in the system.

This is what the form looks like:

<form name ="order_form" method="post" action="add_order_action.php" enctype="multipart/form-data">
                    <table border=1 cellpadding=2 cellspacing=2>
                        <caption>Order Form</caption>
                        <tr>
                            <th align="right"> Property </th>

                            <th align="left"> Value </th>
                        </tr>
                        <tr>
                            <td class="col1"> Name </td>
                            <td class="col2"> <input type="text" name="customer" id ="customer" size=30> </td>
                        </tr>
                        <tr>
                            <td class="col1"> Address </td>
                            <td class="col2"> <input type="text" name="address" id ="address" size=30> </td>
                        </tr>
                        <tr>
                            <td class="col1"> Products </td>
                            <td class="col2">

                                <!-- Interests is an array of all interests in the database-->
                                {foreach $products as $product}
                                <select name="products[{$product.id}][quantity]" id ="quantities">
                                        {section name=quantities start=0 loop=$product.stock + 1 step=1}
                                        <option value="{$smarty.section.quantities.index}">{$smarty.section.quantities.index}</option>
                                        {/section}
                                </select>
                                <input type="checkbox" name="products[{$product.id}][is_checked]" value="1">{$product.name}<br>
                                {/foreach}
                            </td>
                        </tr>
                        <tr>
                            <td colspan=2 align="center">
                                <input type="submit" name="submit" value="Submit">
                                <input type="reset"  name="reset"  value="Reset">
                            </td>
                        </tr>
                    </table>
                </form>

The product names and stock numbers are both from the products table:

create table if not exists SEProducts
(
    id int not null auto_increment primary key,
    price double not null,
    name varchar(30) not null,
    stock int not null,
    original_stock int not null,
    sold_stock int not null
)ENGINE=INNODB;

Now, what I do is that I make an array from the product names that are checked. What I wanna do is associate the values from the dropdown menus, BUT ONLY IF THEY ARE ONE OF THE CHECKED VALUES. Additionally, if a value is checked, the quantity can't be 0. I'm probably doing this an extremely frustrating way but this is what I thought was the best. I could've done a text field but then you'd have to sanitise user input. That'd be okay if it works as opposed to this which doesn't =/

I add the orders by getting the product array:

<?php
include "includes/defs.php";

$customer = $_POST['customer'];
$delivery_address = $_POST['address'];
if (isset($_POST['products'])) 
{
    $products = $_POST['products'];
} 
else 
{
    $error = "An order must consist of 1 or more items.";
    header("Location: list_inventory.php?error=$error");
    exit;
}

$id = add_order($customer, $delivery_address, $products);

header("Location: order.php?id=$id");
exit;
?>

Then my add order function works like this:

function add_order($customer, $delivery_address, $products)
{
    $connection = mysql_open();
    $customer = mysql_escape_string($customer);
    $delivery_address = mysql_escape_string($delivery_address);

    $query = "insert into SEOrders (name, address, status) " .
             "values ('$customer', '$delivery_address', 'New')";
    $result = mysql_query($query, $connection) or show_error();

    $id = mysql_insert_id();

foreach ($products as $product)
    {
        if ($product['is_checked'] != 0 && $product['quantity'] != 0)
        {
            $query2 = "insert into SEOrder_items (order_id, product_id, quantity) " .
                    "values ('$id', '$product.id', '$product.quantity')";
            $result2 = mysql_query($query2, $connection) or show_error();
        }
    }

mysql_close($connection) or show_error();
return $id;
}

I was thinking I might have to do some JavaScript but I'm absolutely rubbish at that.

If I wasn't able to explain myself: Long story short; I need to add quantities to the products array but only if the products are checked and the quantity is > 0.

Thanks in advance, Cheers:)

EDIT: I've made some changes but now I get the following error: Error 1452: Cannot add or update a child row: a foreign key constraint fails ( db/SEOrder_items , CONSTRAINT SEOrder_items_ibfk_2 FOREIGN KEY ( product_id ) REFERENCES SEProducts ( id ))

Answer 1

As a first step I would combine the products- and quantities-arrays, so the quantities, the check-box and the product-name are in one array:

<select name="products[{$product.id}][quantity]" id ="quantities">
…
</select>
<input type="checkbox" name="products[{$product.id}][is_checked]" value="1" />

would result in following array (where 1 and 2 are the products-ids, 'is_checked' is only set if the box was checked):

$_POST['products'] = array(
    [1] => array(
        'quantity' => 3,
        'is_checked' => 1,
    ),
    [2] => array(
        'quantity' => 1,
        // not checked
    ),
);

It should be easy to get through such an array using:

foreach($_POST['products'] as $currentProductId => $currentProductArray)

Answer 2

I think you just need to tweak your logic and your template a little bit.

First, you want to drive the whole thing from the products that are available on the ordering page rather than the products that come back; this:

if (isset($_POST['products'])) 
{
    $products = $_POST['products'];
} 
else 
{
    $error = "An order must consist of 1 or more items."
    header("Location: list_inventory.php?error=$error");
    exit;
}

Should look more like this:

$products = the_products_list_that_you_sent_to_the_page();

Of course, if the products list is massive then you'll be stuck pulling the products list out of the page (and validating each product) as you're doing now. However, if the products list is small then it is easier to start with a known and valid list.

The meat of the issue is your database interaction and how add_order works. Your add_order gets a list of products to look at in $products . All you need to do is this:

• Create an array of data to be inserted.
• Go through $products , if the product is checked and it has a quantity, add it and its quantity to the list.
• Check if there is anything in the order list after the above loop is finished:
  • If there is something in the order list, add_order can add it all to the database.
  • If there isn't anything in the order list, add_order can return an error code (such as an order ID of zero) and the caller can complain to the user that ordering nothing at all makes no sense.

The basic strategy is to collect your data and then act on it rather trying to act on your data while you collect it.

Now the problem becomes: how do we associate a quantity with a specific problem? This is easy to solve as we have product IDs; your <select> elements should be:

<!--
  Note that this also avoids the evil of having
  duplicate id attributes in one page
-->
<select name="quantity_{$product.id}">

Then, when you're looking for the quantity of a specific product, you can pull it straight out of $_POST as a scalar as $q = $_POST['quantity_'. $product_id] $q = $_POST['quantity_'. $product_id] .

I know I could have solved the root of your problem just by telling you to rename your <select> elements but I figured I'd sort out some of your other possible issues along the way.