Sending unknown number of variable parameters to new page in HTML

Before I get started I wanted to say that I am not a web server expert so if you know of a better way to do this, post it in the comments and I will thank you as I implement your knowledge in my game.

When using PHP you eventually come to the realization that your gatekeepers for everything you do and display are HTTP and HTML.  They are both great tools but were designed with a more static implementation in mind. Values passed to new web pages are set up in key->value pairs that are accessed with an associative array using the name of the parameter as the key (ie. $_POST['myParam']).  This post will deal with the issue of how to send an unknown number of parameters which are user set to a new page which can then use those parameters correctly.

My particular implementation is my Mining page in my game TerraTanks.  The mining page allows the user to set the type of mining on each of their planets so that if they are deficient in a particular resource, they can mine it out faster.  I wanted to make sure that this could be changed globally, so the mining page will show all of your planets and each planet will have a set of radio buttons allowing you to change the mining settings.  With these constraints, you cannot know how many planets the user will have and you must write your code to account for any number of parameters.

This is a simplified version of what I have:

$count = 0;
 
// I have the result set for all my mining planets in $result
while ($result && $element = mysql_fetch_object($result))
{
    // code displaying what I need about planet //
 
    echo "<INPUT TYPE=\"radio\" name=\"miner{$count}\" value=\"normal,$element->location\" checked>Normal";
    echo "<INPUT TYPE=\"radio\" name=\"miner{$count}\" value=\"iron,$element->location\">Iron";
    $count++;
}

I am creating the name of the radio button group by appending the value of $count the the word miner and then incrementing count as long as there are planets. Basically, I am hacking together my own array. It should be noted that I am setting the first radio button to the checked state. The web page that will read the input depends on everything that exists having a value so it is necessary to make sure that something is selected. In your work you will want to check what the value is previously set to and make sure the correct radio button is checked when the page loads.

You may also notice that I am shoving a lot of data into the value sent appended by commas. This is a decent way of shoving related data through without having to define a ton of variables.

Now we have to create something on the receiving page that will correctly read in the values that we are sending. This is the code that I am using:

$x = 0;
$indexName = "miner" . $x;
while ($_POST[$indexName])
{
	$miner[$x] = $_POST[$indexName];
	$x++;
	$indexName = "miner" . $x;	
}

If you read the code in English it roughly says, as long as there is a POST value at the index miner{$x} where $x starts at 0 and increments by one then just keep incrementing $x and saving the value into my own array. This is why it was so important that as long as you had a planet you had a value that was passed. If you set a value for planet 0, 1, and 5 but not 2, 3, or 4 then the code would stop at 2, determine there was no value and would never get to 5.

Now instead of creating a second pseudo array with hidden inputs that pointed to the location of the planet, I packed all the information into a comma appended string. When I get the value of $miner[$x] I can use the php function explode to separate out the sub values.

$minerParts[$x] = explode (",", $miner[$x]);
 
// now $minerParts[$x][0] is the mining type and $minerParts[$x][1] is the location

So there is a way to send an unknown number of variables to a new page. Like I said, if you know of a better way make sure you post it in the comments. I don’t claim to be an expert on this subject, it is just how I resolved this problem.

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Jake is a games nut. He flips out and makes games without even thinking twice about it. He is good at rulesets, balancing (games, not on a beam you idiot), and knows things about coding. Like all mammals, Jake likes board and video games and makes both (like www.terratanks.com). Jake constantly fights his arch enemy Sarcastro and hopes knowledge of his weakness, visual design, never falls into the wrong hands.

Wednesday, September 17th, 2008 code, php, terratanks, tutorial
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