Ajax. What is the easiest way to recieve data from PHP?

**al9** · Oct 19, 2007, 22:49

Hello guys,

I've read view articles about how to dynamically recieve data from server with Ajax, but they are too complicated for me. I wonder what technique do you use? Which one is the easiest one?

**jimfraser** · Oct 21, 2007, 00:17

check out the JSON library @ http://json.org

**Ize** · Oct 21, 2007, 02:07

I've used different ways of fetching data from a PHP file.
I started out using just strings, in which name-value pairs are separated by a certain character, like this;

Code:

foo=70::--::bar=90::--::baz=19

// split string on "::--::"

This is very light-weight and works fine in most cases, but it's much easier to print some XML with PHP. The biggest advantage is that you can use the build-in DOM methods, such as getElementsByTagName().

**al9** · Oct 21, 2007, 05:08

Originally Posted by jimfraser

check out the JSON library @ http://json.org

Thanks Jim, I already use some JSON one my site (with 3rd party scriprs). But I'd really will be happy to see some eample to see how does it work with JSON. If you don't have a link to any exaple, I'll ve glad to listen about idea where can I find it.

Originally Posted by Ize

This is very light-weight and works fine in most cases, but it's much easier to print some XML with PHP. The biggest advantage is that you can use the build-in DOM methods, such as getElementsByTagName().

Can you show me some example please (even some small one), so I can inderstand how it works?

**jimfraser** · Oct 21, 2007, 11:48

There are several PHP JSON libraries listed on that page with a comparison of the pros/cons of each.

On the javascript side, the library gives you 2 main functions:

foo.toJSONString() - returns a serialized string that holds the data contained in foo ready to send via ajax or whatever to php

string.parseJSON() - takes a serialized string and returns a variable/data structure

**al9** · Oct 23, 2007, 07:44

Originally Posted by jimfraser

There are several PHP JSON libraries listed on that page with a comparison of the pros/cons of each.

On the javascript side, the library gives you 2 main functions:

foo.toJSONString() - returns a serialized string that holds the data contained in foo ready to send via ajax or whatever to php

string.parseJSON() - takes a serialized string and returns a variable/data structure

Thanks Jim. However I wouldn't call this simple.

I wonder, is there any similar method to get data from PHP as this simple way to send data to PHP?

**jimfraser** · Oct 23, 2007, 13:18

You mentioned Ajax in your first post - this refers to using xmlhttprequest objects. The technique used in your link creates image objects and uses them to send data to the server, but you can only receive data from php to javascript using xmlhttprequest. So I think you'll have to bite the bullet.

**al9** · Oct 24, 2007, 01:53

Originally Posted by jimfraser

You mentioned Ajax in your first post - this refers to using xmlhttprequest objects. The technique used in your link creates image objects and uses them to send data to the server, but you can only receive data from php to javascript using xmlhttprequest. So I think you'll have to bite the bullet.

No problem, I will learn JSON/PHP method. I just wanted to find out simpliest way to receive data. It seems this method is simpliest...

Thanks for help Jim.

**wonshikee** · Oct 24, 2007, 06:45

The simpliest method of getting data from PHP is..

echo $str;

Usually all you're doing is fetching some simple strings from PHP, and all you have to do is output it. Which will get picked up by ajax.responseText.

**jimfraser** · Oct 24, 2007, 15:39

This is true - JSON is a much more complex model used if you need to retrieve arrays, objects, etc from PHP. If you are simply displaying text or HTML retrieved via AJAX from the server you can just write out the text to a div. Here's an example I found at http://www.omnytex.com/articles/xhrstruts/

Code:

<html>

<head>

<title>Example 2</title>

 

<script>

 

  var req;

  var which;

 

  function retrieveURL(url) {

    if (window.XMLHttpRequest) { // Non-IE browsers

      req = new XMLHttpRequest();

      req.onreadystatechange = processStateChange;

      try {

        req.open("GET", url, true);

      } catch (e) {

        alert(e);

      }

      req.send(null);

    } else if (window.ActiveXObject) { // IE

      req = new ActiveXObject("Microsoft.XMLHTTP");

      if (req) {

        req.onreadystatechange = processStateChange;

        req.open("GET", url, true);

        req.send();

      }

    }

  }

 

  function processStateChange() {

    if (req.readyState == 4) { // Complete

      if (req.status == 200) { // OK response

        document.getElementById("theTable").innerHTML = req.responseText;

      } else {

        alert("Problem: " + req.statusText);

      }

    }

  }

 

</script>

 

</head>

<body onLoad="retrieveURL('example2RenderTable.do');">

 

<h1>Example 2</h1>

Dynamic table.<hr>

<p align="right"><a href="home.do">Return home</a></p><br>

This example shows how a table can be built and displayed on-the-fly by showing

sorting of a table based on clicks on the table headers.

<br><br>

 

<span id="theTable"></span>

<br>

 

</body>

</html>

**wonshikee** · Oct 24, 2007, 16:05

For one dimensional arrays you can just echo out a | (or whatever) separated string, and with javascript just split it and create the array you need.

**al9** · Oct 25, 2007, 08:11

What would you say about this tutorial? I've tried their sample on my server, but it didn't work. They have working sample in the end of the tutorial, but it doesn't work also (Firefox, Mac).

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