[RESOLVED] Multiple drop-down boxes

aescott

Firstly, apologies if this has already been answered, but I've had a look and can't find anything which matches my problem closely enough to be of use.

I have to extract an identifier from MySQL and then split the identifier into its 4 constituent parts. This will give me

Part A
Part B
Part C
Part D

Parts B to D are dependent on the preceeding choices, made via drop-down boxes. I have used Javascript to reload the page and then $_GET the info from the URL - so far, so good. However, this only works for Part A. When Part B is selected, that value is captured but the value from Part A is lost.

How do I retain both Parts to allow me to then select Part C? Do I need to pass the Part A PHP variable to a Javascript function, which would then create new variables for both A and B, which would then be retrieved using $_GET? If so, how do I do this?

Thanks a lot.

bretticus

You will get more responses if you explain your issue more clearly. Frankly, your question is a little hard to follow. For example, you speak of an "identifier" from your database that you have to extract into 4 parts. However, then the "identifier" is chosen from dropdown menus. Then, you are using javascript to read location.href to build out the menus. Is this a javascript question pretty much? Quite confusing about what you are up to.

Can you provide some code perhaps with a better explaination? I dunno if I'll be around to help answer (unless it's tonight failry soon) however, what you ask sounds like it might be worthwhile and you will get some help on here. You just need to explain it better and let a few snippets of code do the talking.

aescott

I've attached my code (with a .txt extension rather than .php to allow it to be uploaded).

The database (connection removed in code) is queried for a unique site identifier. The identifier is made up of:

a town
a location within the town
a room at the location
a flag for the type of information collected

I need to split these out and populate 4 drop-down boxes with the results.

My code is supposed to refresh the page each time a selection form a box is made, which it does, but it loses all previously made selections, e.g.

First Pass - select town
Town selected = Glasgow
location = <null>
room = <null>
flag = <null>

Second pass - select location
Town selected = <null>
location = High Street
room = <null>
flag = <null>

How do I retain the information for each drop-down box and end up with 4 values? I'm fairly new to PHP / Javascript and know next to nothing about Ajax.

Hope this is clear?

bretticus

Much better explanation!

Usually if i do something like this, I use javascript to dynamically build each menu as needed. There are many ways to go about this: For example, post onchange for each page will basically send through the value of each select box. Or, to avoid a page reload again (if you had lots of potential dropdown box data) you could even use ajax to query the database and populate the subsequent dropdown box. And there's your current way which is pretty creative and effective. When you repost or use get (such as in your example) you need just one step to make it work: you need to use the values in the $_GET superglobal to reset your selected option on page load. Simply, just put some if logic in your loop for building out options. Perhaps something like:

echo "<select name='site_sel' onchange=\"reload(this.form)\"><option value=''>// Start first drop down list 
	//populate with values from the unique list
	echo "<br />Select the site<br />";
	echo "<select name='site_sel' onchange=\"reload(this.form)\"><option value=''>Select one</option>";
	$entry = 0;
	while(($unique_site[$entry]) != NULL)
	{ 
		echo "<option";
		echo ($_GET['site_sel']==$unique_site[$entry]) ? " selected" : "";
		echo ">".$unique_site[$entry]."</option>";
		$entry++;
	}
	echo "</select><br />";
	//End first drop down list

Notice as we are looping through the while, we just check to see if the current option value is the same value passed from the $_GET superglobal. If it is, we simply echo out " selected."

Now I didn't delve into your code indepth. So hopefully I'm not totally off the mark. However, I think this is the one step that you are lacking to complete what you need to do.

aescott

Thanks - all working now. CAn now focus on other issues....