Dropdown change Event in PHP....

Question

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Suppose we have two dropdown
dropdown1 for country and dropdown2 for state

i want to show the states in dropdown2 on dropdown1 change event(when we select any country then show states of particular country in dropdown2 from database)?

Posted 21-Sep-12 1:35am

Surendra0x2

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2 solutions

Solution 2

Hi Again,
Here's an Example... A Complete Test Page with this feature

File: index.html

HTML

<!doctype html>
<html>
<head>
 <meta charset="utf-8">
 <title>Representation of AJAX</title>
 <script type="text/javascript">
   function update(str)
   {
      var xmlhttp;

      if (window.XMLHttpRequest)
      {// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp=new XMLHttpRequest();
      }
      else
      {// code for IE6, IE5
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
      }	

      xmlhttp.onreadystatechange = function() {
        if(xmlhttp.readyState == 4 && xmlhttp.status == 200)
        {
          document.getElementById("data").innerHTML = xmlhttp.responseText;
        }
      }

      xmlhttp.open("GET","demo.php?opt="+str, true);
      xmlhttp.send();
  }
</script>

</head>
<body>
  <select id="optionA" onchange="update(this.value)">
    <option value="0">Select...</option>
    <option value="1">Option1</option>
    <option value="2">Option2</option>
  </select>
  <br/>
  <select id="data">
    <option>Select an Option...</option>
  </select>
</body>
</html>

File: demo.php

PHP

<?php
  $opt = $_GET['opt'];

  switch($opt)
  {
    case 0:
    default:
      echo '
            <option>Select an Option...</option>
           ';
        break;
    case 1:
      echo '
            <option value="opt1_1">Option1_Test1</option>
            <option value="opt1_2">Option1_Test2</option>
            <option value="opt1_3">Option1_Test3</option>
           ';
        break;
    case 2:
      echo '
            <option value="opt2_1">Option2_Test1</option>
            <option value="opt2_2">Option2_Test2</option>
            <option value="opt2_3">Option2_Test3</option>
           ';
        break;
  }
?>

Hope that this example will help.

With Regards
Tushar Srivastava

Posted 16-Dec-13 2:49am

Er. Tushar Srivastava

Updated 16-Dec-13 2:50am

v2

Comments

Mr.Venus 17-Dec-13 4:52am

Thank you very much Tushar sriv . I am a Newbie in coding :( So I cannot understand ajax,php codings.. anyway Thanks for your help. I have tested this on my computer. It worked. I am very happy now. Kindly give me some learning resources for programming

Er. Tushar Srivastava 17-Dec-13 7:03am

It is a pleasure to help peoples :) I am always here to help. Well for learning resources on internet, I would like to tell you two things. If you retain or learn better by audio visual source then you can go for video tutorials on youtube or net.tutsplus but if you are more comfortable in reading and understanding than no one is better friend's of yours than your favorite books :) Enjoy learning and always challange yourself to do big. Its how I have learned :) Best of Luck

Mr.Venus 18-Dec-13 1:22am

Thank you very much dude :) And also I have one doubt, U have used switch case in php from above example. Is it possible to use that by using arrays? If yes ? just give me a example of full code. Thank u once again

Er. Tushar Srivastava 18-Dec-13 5:07am

Actually it is possible but I am sure the code will look seriously clumsy using that technique 'cause then you have to build an array containing the code as element and then you will be using the index received via a GET request to echo that element. It is better to stick to this solution :) BTW, you can try doing what I have given you as a homework hint ;) Best of Luck Buddy!!!

Mr.Venus 20-Dec-13 0:20am

Tnank u :( I have tried that by using ararays. Still I was stuck with them. There are so many types of arrays. I dont know which one is efficient to above scenerio.Kindly give me the demo of php arrray for above scenerio

Er. Tushar Srivastava 21-Dec-13 22:52pm

There are three types of arrays in php. The most common is indexed array. In this array, all the elements are indexed like 0, 1, 2 ... The next type is enumerated array where instead of fixed index you can have variable number (enumeration) for each element. The last type is called associative array. In this type of array the key also is a string so it is easy to use. For example, an array's element represented by $arr['ID'] is more understandable than indexed array $arr[0]. Now in your case I guess that simple index array will solve the problem. Yet it's upto your logic for what you want to use. :)

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Er. Tushar Srivastava · Accepted Answer · 2012-09-21T04:41:00

Well, My Friend, I am sure to help you since I have already replied to such a question previously too.
Let us see, how to do it...

1. First thing you need to think is, how will it be updating... ie. will the page reload or will it update automatically (obviously we will be going with the second one).

2. So, we are going with second one, we will need AJAX to do so.... Now it's your job to implement it. i can only give you idea.

3. The next thing is, make a page which can be called as processor, whenever a the name of country is submitted to this page, (you will be doing so using ajax) it will return you will a list of name of states. See the codes below..(sorry, it is in php but I am sure you can implement it for ASP as well)

PHP

foreach($array as $statename)
{
 echo "<option>".$statename."</option>";
}

This way the data is now recieved by you... Now paste this data inside the dropdown list using ajax as..

JavaScript

document.getElementByID("statelist") = xmlhttp.responseText;

Now here will be your codes inside the form: