CODEWITHSUNDEEP
phpjavascriptmysqlajax
Dan Harris
Dan Harris

Reputation: 1396

Ajax approach to populating a second dynamic dropdown based on the selection in the first

I've not used much Ajax before, and this seems simple. I have the seperate parts to the puzzle, but not sure how to put them together.

Both dropdowns are populated from the database, the first is populated using the following code:

<?php
$sql = "SELECT title, nid FROM node where type= 'hotel'";
$hotels = mysql_query($sql);
?>
<select name="hotels" id="hotels">
<?php
while($row = mysql_fetch_array($hotels))
{
  echo "<option value=\"".$row['nid']."\">".$row['title']."\n  ";
}
?>
</select>

The second dropdown should be populated based on the value selected above. So basically I want to take the id of the selected item and then use that in a query to populate the second dropdown.

I would use the above code, but with the following for the SQL query:

SELECT title, nid from node where type = 'season' AND hotel_nid = X

Where X is the id of the selectedIndex on the first dropdown.

Althought the code is there to work, I don't know how to combine the two. I could use Javascript to modify the InnerHTML of a div called "seasons" by printing the code to retrieve and display the dropdowns.

But is there a better way where I can have both the dropdowns visible, but the second is disabled until the first is completed?

Upvotes: 0

Views: 4298

Answers (2)

Nabab
Nabab

Reputation: 2654

Your PHP script populating the second list should be called through Ajax when the user changes the value of the first dropdown. So you should add onchange="myFunctionToPopulate(this.value);" to the first dropdown.

If you don't know how to do that I'd suggest also you use a JS library such as jQuery, and we will post you the simple code to achieve this.

Edited

With jQuery, you can do something like this: 

<select name="first_dropdown" onchange="$('#dropdown2_container').load('your_script.php?nid='+this.value);">
  <option....
</select>
...
<div id="dropdown2_container" style="display:none"> </div>

Where your_script.php would return the whole select tag.

Upvotes: 1

Spiny Norman
Spiny Norman

Reputation: 8347

you could use fill the innerHTML of your <select> box instead of a <div>, but I would really advise you to have a look at jQuery: http://api.jquery.com/category/ajax/. It makes everything a lot easier.

Upvotes: 1

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