[RESOLVED] Forms based on selection

gitosh

Hi guys, I'm new in PHP and I have a problem. I have two form select elements which are being populated from a microsoft sql database.
I need the second select element's contents to be based on the selection in the first select element.
For example like say the first select element has a list of countries and then when you select a country, the second select element is populated with the cities in that country. any help will be highly appreciated

bpat1434

well, in your combo-box, you'd have an onChange event which submits that combobox form. Your PHP page would see that the combobox field isn't empty, and would act accordingly to fire off a different query populating the next one.

I don't have time to write it out, but the basic idea is this:

1.) User selects item in Combobox
2.) Combobox onChange submits form
3.) PHP sees a non-empty Combobox value
4.) PHP executes a query to get information based upon what the new value is
5.) PHP displays the page again with two comboboxes, the original (with "country" already selected), and the new one

Repeat that as necessary until you fill all your combobox needs.

gitosh

I get the idea but the code is the problem, a link to an article with example code would also be appreciated

bpat1434

Don't know of any tutorials, but here's some code, and a working example:

<?php

echo '
<form action="'.$_SERVER['PHP_SELF'].'" method="post">';

echo '
<select name="combo1" onChange="this.form.submit();">';
if(empty($_POST) || !isset($_POST['combo1'])) {
	echo '
	<option value="null" selected="selected">Please Select...</option>';
}
$c1 = (isset($_POST['combo1']) && !empty($_POST['combo1'])) ? $_POST['combo1'] : '';

echo '
	<option value="first"'.(($c1=='first')?' selected="selected"':'').'>First</option>
	<option value="scnd"'.(($c1=='scnd')?' selected="selected"':'').'>Second</option>
	<option value="third"'.(($c1=='third')?' selected="selected"':'').'>Third</option>
</select>';

if(isset($_POST['combo1']) && !empty($_POST)) {
	$c2 = (isset($_POST['combo2']) && !empty($_POST['combo2']))?$_POST['combo2']:'null';
	echo '
<select name="combo2" onChange="this.form.submit();">
	<option value="null"'.(($c2=='null')?' selected="selected"':'').'>Please Select...</option>';

if($_POST['combo1'] == 'first') {
	echo '
<option value="a"'.(($c2=='a')?' selected="selected"':'').'>Part A</option>
<option value="b"'.(($c2=='b')?' selected="selected"':'').'>Part B</option>';
}
else if($_POST['combo1'] == 'scnd') {
	echo '
<option value="c"'.(($c2=='c')?' selected="selected"':'').'>Part C</option>
<option value="d"'.(($c2=='d')?' selected="selected"':'').'>Part D</option>
<option value="e"'.(($c2=='e')?' selected="selected"':'').'>Part E</option>';
}
else if ($_POST['combo1'] == 'third') {
	echo '
<option value="z"'.(($c2=='z')?' selected="selected"':'').'>Part Z</option>
<option value="y"'.(($c2=='y')?' selected="selected"':'').'>Part Y</option>
<option value="x"'.(($c2=='x')?' selected="selected"':'').'>Part X</option>
<option value="w"'.(($c2=='w')?' selected="selected"':'').'>Part W</option>
<option value="v"'.(($c2=='v')?' selected="selected"':'').'>Part V</option>';
}

echo '
</select>';
}
if($_POST['combo1'] !== 'null' && $_POST['combo2'] !== 'null') {
	$c1 = $_POST['combo1'];
	$c2 = $_POST['combo2'];

switch($c1) {
	case 'first':
		switch($c2) {
			case 'a':
				echo 'A';
				break;
			case 'b':
				echo 'B';
				break;
		}
		break;
	case 'scnd':
		switch($c2) {
			case 'c':
				echo 'CC CC';
				break;
			case 'd':
				echo 'DD DD';
				break;
			case 'e':
				echo 'EE EE';
				break;
		}
		break;
	case 'third':
		switch($c2) {
			case 'z':
				echo 'ZZZ ZZZ ZZZ';
				break;
			case 'y':
				echo 'YYY YYY YYY';
				break;
			case 'x':
				echo 'XXX XXX XXX';
				break;
			case 'w':
				echo 'WWW WWW WWW';
				break;
			case 'v':
				echo 'VVV VVV VVV';
				break;
		}
		break;
}
}
echo '
</form>';
?>

Working Example

Yes, it's over-simplified. But you can get the general idea of how to do it and adapt as needed. And if you're using a mySQL database, it's much easier.

gitosh

Hi Bpat,

Thanks to your help, I'm now making some progress, but I have a small problem. When I populate the select element from the database and then try to select an item in the list, it goes back to the first item example lets say I have populated the select element from the database and the items have come in the following order

USA
Canada
Kenya
India
when I select say Kenya, the select element defaults to USA . ie it doesn't maintain the selected item if that item is not the first one in the list, in this case USA. what could be the problem? Thanks in advance.

bpat1434

The problem is you're not checking what the $POST['country'] value is as compared to the current mySQL row value. Basically, you're missing this step:

(($c1=='first')?' selected="selected"':'')

from my code above (obviously you'd have a different variable name, and "first" would be the current $_POSTed country).

gitosh

Hello Bpat,
Could you please tell me what I'm doing wrong in this code because it's not working

while ($row=mssql_fetch_array($result))
{
$cl = (isset($POST['cbodist']) && !empty($POST['cbodist'])) ?
POST'cbodist'] : '';
echo "<option value={$row['DistCode']}'.(($cl==$row['DistCode'])?' selected='selected'':'').'>{$row['DistName']}</option>";
}

cbodist is the name for my first select element
DistCode is one of the columns I'm returning and DistName is the other
$result is the result set

bpat1434

You start with double quotes, then never really get out of the string to try and do the comparison... this is where a colored editor really helps:

while ($row=mssql_fetch_array($result))
{
$cl = (isset($_POST['cbodist']) && !empty($_POST['cbodist'])) ?
POST'cbodist'] : '';
echo "<option value={$row['DistCode']}'.(($cl==$row['DistCode'])?' selected='selected'':'').'>{$row['DistName']}</option>";
}

It should be:

while ($row=mssql_fetch_array($result))
{
$cl = (isset($_POST['cbodist']) && !empty($_POST['cbodist'])) ?
POST'cbodist'] : '';
echo '<option value="'.$row['DistCode'].'"'.(($cl==$row['DistCode'])?' selected='selected'':'').'>'.$row['DistName'].'</option>';
}

Notice the difference?

gitosh

Hi Bpat,
I get the difference and I have done the neccessary changes, and now I'm getting the following error on this line

echo '<option value="'.$row['DistCode']'"'.(($cl==$row['DistCode'])?' selected='selected'':'').'>'.$row['DistName'].'</option>';

Parse error: parse error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting ',' or ';'

bpat1434

Missing a period....

Code']'"'

should be

Code'].'"'

That's my bad too... sorry.

gitosh

Hi bpat,
wow! how do you notice the small details? I hate to ask this but after solving that problem I got another error on the same line which is
Parse error: parse error, unexpected T_STRING
and I'm not missing a semi colon on the previous line, here is the whole block of the while again.
while ($row=mssql_fetch_array($result))
{
$cl = (isset($POST['cbodist']) && !empty($POST['cbodist'])) ? $_POST['cbodist'] : '';
echo '<option value="'.$row['DistCode'].'"'.(($cl==$row['DistCode'])?' selected='selected'':'').'>'.$row['DistName'].'</option>';

$dc=$_POST['cbodist'];
  }

echo '</select>';

bpat1434

This:

selected='selected''

Needs to be this:

selected="selected"'

Using a colored editor will help tremendously in catching those types of errors.

gitosh

Hi Bpat,
Thanks alot men, it's now working well and I've learnt alot from you. and by the way I'm using Macromedia Dreamweaver, do you think there is a better editor?

bpat1434

Well, there is debate; however, it does what you need. I'd suggest just taking a look at the code when you're done. You'll notice some things as you code more. And eventually small things like this are very quickly detectable with a colored editor (like Dreamweaver).