Tip for pre-selecting select box item

[freebie]

Just thought I'd share something I figured out today. In administration "edit item" interfaces, you often have select boxes, and you want to select the item that corresponds with the entry for that field in the database. I used to do this purely with PHP (and thus having to compare each and every item in the options list). I figured out that using a javascript function, and then writing out calls to that function (dynamically using PHP) is much much quicker.

Here's the javascript function I created:

// javascript not php
function showSelectBoxSelectedItem(sbox, valueToSet){
for (loop = sbox.options.length-1; loop > 0; loop--) {
if(sbox.options[loop].value==valueToSet){
sbox.selectedIndex=loop;
break;
}
}
}

Then, at the bottom of the page (to make sure the form field you are targeting has already loaded), add PHP similar to this to write out your javascript function calls.

echo "<script language='javascript'>\n\t";
echo "showSelectBoxSelectedItem(document.forms[0].InterviewYear,'".substr($myrow['InterviewDate'],0,4)."')\n\t"; 
echo "showSelectBoxSelectedItem(document.forms[0].InterviewMonth,'".substr($myrow['InterviewDate'],5,2)."')\n\t"; 
echo "showSelectBoxSelectedItem(document.forms[0].InterviewDay,'".substr($myrow['InterviewDate'],8,2)."')\n"; 		 		 
echo "</script>";
?>

Hope this helps someone. Sure seems to save a lot of time (in a non-templated environment).

[kanchi]

Hi Freebie:
I just joined phpbuilder and was looking at your code and there is some similarity on what i am trying to do
What i am trying to do is pre select a list box item depending upon what value is passed but the complexitty here is that the list box is dynamically fill with the item from the database
Here is my code:

<select name="teamName">
<?
for ($i=0;$i < $num_result;$i++) {
$value=mssql_result($result,$i,"team_id");
echo "<option value=$value selected>";
$teamName=mssql_result($result,$i,"teamName");
echo $teamName;
echo "</option>";
}
?>

this code always selects the last listed item on the list box but what i want to be able to do is to preselect the list item on when the form loads depending on what value was passed to the file from a link on another file . I also want to maintain the dynamic filling of the list box with items.

Please help if u know any thing on it.
Thanx

[leatherback]

Hey Freebie,

Ay you know, nothing in life is for free, and so is your solution. It assumes that all users have their browser set to accept javascript, which is not true.

However, yu can of course write a similar function in PhP.

J.

[kanchi]

Hi Freebie:

Sorry abt the trouble

I figured it out, just needed an if statement comparison inside the for loop.

It is working the way I want.

Thanks anyway

---

Hello leatherback: thank you for the advice

• Codes provide logic/technique answers, not full working solutions
• Use: or die(mysql_error()) after each query and safe a headache
• use print_r($variable) to see the values in that variable
• Read the manual, browse the forum, try and THEN ask
  ------------------------

It worked for me.