HTML form with checkbox and number types submission with PHP?

Question

For learning purposes, I'm doing this website where user can select some items and the number of units he wants, let's say it's this simplest shopping app.

So, I read from database the existing items in catalog:

$queryResult=$mySQL->query("SELECT nombre, precio, id FROM productos");

Then I print the list of products:

    $queryResult=$mySQL->query("SELECT nombre, precio, id_producto FROM productos");
    echo "<form action=\"checkout.php\" method=\"POST\">";
    while($datos=$mySQL->fetch_array($queryResult))
    {   
        $nombre=$datos['nombre'];
        $id_producto=$datos['id_producto'];
        $precio=$datos['precio'];

        echo "<h1>$nombre</h1>";
        echo "<input type=\"checkbox\" name=\"$id_producto\" value=\"on\"> Cantidad: <input type=\"number\" name=\"$id_producto"."Number\""." min=\"1\" max=\"20\" step=\"1\" value=\"1\"><br>";
        echo "<h3>Precio: $precio</h3><br>";

    }

    echo "<br>";
    echo "<input type=\"submit\" class=\"button\" value=\"Comprar\">";
    echo "</form>";

They get as value the ones from $id_producto, in the case of the number type inputs I concatenate "Number" so they dont get the same name.

After submission, I'm trying to do something like:

foreach($_POST as $post_key => $post_value){     

    if ($post_value=="on") {
        $var1 = $_POST['.$post_key."Number".'];
    }
}

So if a checkbox was selected I check for its corresponding numeric value.

Is it OK to perform another $_POST['somevariable'] inside that loop?
How can I concatenate that argument inside the square brackets?

try replacing $_POST['.$post_key."Number".'] to $_POST[$post_key."Number"] — Dipesh Parmar
– Dipesh Parmar, Commented Oct 24, 2013 at 3:29

Barmar · Accepted Answer · 2013-10-24 03:32:04Z

1

You don't need the single quotes, that's for when the key is a constant string. Since your key is an expression, just put that expression inside the brackets:

if ($post_value=="on") {
    $var1 = $_POST[$post_key."Number"];
}

A better way to do this is to post the inputs as arrays:

echo "<input type=\"checkbox\" name=\"producto[]\" value=\"$id_producto\"> Cantidad: <input type=\"number\" name=\"Number[$id_producto]\" min=\"1\" max=\"20\" step=\"1\" value=\"1\"><br>";

Then you can use the loop:

foreach ($_POST['producto'] as $post_value) {
    $var1 = $_POST['Number'][$post_value];
}

answered Oct 24, 2013 at 3:32

Barmar

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5 Comments

diegoaguilar Over a year ago

Why would the $_POST index would be from a matrix?

Barmar Over a year ago

When you use name="xxx[]", PHP collects all those inputs into an array in $_POST['xxx'].

diegoaguilar Over a year ago

So the ['Number'] part in $var1 = $_POST['Number'][$post_value]; sentence is quite PHP-ish?

Barmar Over a year ago

It comes from <input type="number" name="Number[$id_producto]">.

diegoaguilar Over a year ago

I get now! There will be simple ones like $_POST['cat'] if I have any input with name cat, and in this case checks for the $_POST['Number']'s ones

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