The Curly Braces PHP

Handling JSON request in PHP

I’ve been working with PHP and jQuery AJAX quite a bit lately. Along with sending form data to PHP page through AJAX, I’ve written restful web services in PHP that receive data in JSON format.

In general when you are sending data through jQuery AJAX to PHP, you don’t have to specify a contentType. Depending on your type ‘GET’ or ‘POST’, PHP will nicely wrap your content into either the $_POST or $_GET global arrays. When you don’t specify a contentType the default contentType is taken as application/x-www-form-urlencoded; charset=UTF-8’.

Following is the request headers from an AJAX call without contentType specified,

GET /ajax-php/api.php?firstname=Abijeet&lastname=Patro HTTP/1.1  
Host: localhost:8081  
Connection: keep-alive  
Cache-Control: no-cache Pragma: no-cache  
Accept: */*  
X-Requested-With: XMLHttpRequest  
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.143 Safari/537.36  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
Referer:http://localhost:8081/ajax-php/index.php  
Accept-Encoding: gzip,deflate,sdch  
Accept-Language: en-US,en;q=0.8,fr;q=0.6  

To further test this, I set up the following PHP code on my server,

$get=$_GET;
$post=$_POST;
$app_json=json_decode(file_get_contents('php://input');
$response=array();
$response['GET']=$get;
$response['POST']=$post;
$response['JSON']=$app_json;
echo json_encode($response);  
die();  

The response that for the above request case was,

{"GET":{"firstname":"Abijeet","lastname":"Patro"},"POST":[],"JSON":null}

If we put the jQuery AJAX type property as ‘POST’ we will have the following request header,

POST /ajax-php/api.php HTTP/1.1  
Host: localhost:8081  
Connection: keep-alive  
Content-Length: 32  
Cache-Control: no-cache  
Pragma: no-cache  
Origin: http://localhost:8081  
X-Requested-With: XMLHttpRequest  
Content-Type: application/x-www-form-urlencoded;  
charset=UTF-8  
Accept: */*  
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.143 Safari/537.36  
Referer: http://localhost:8081/ajax-php/index.php  
Accept-Encoding: gzip,deflate,sdch  
Accept-Language: en-US,en;q=0.8,fr;q=0.6  

Nothing much changes. The action is specified as POST and the data is no longer a part of the request header. The response from the server is following,

{"GET":[],"POST":{"firstname":"Abijeet","lastname":"Patro"},"JSON":null}

Obviously, PHP has no issues parsing content of type - application/x-www-form-urlencoded; charset=UTF-8. As soon as it sees that contentType, it checks the action and packs the data nicely into either $_GET or $_POST.

Let’s now talk about JSON data. In general, restful web services accept data of type JSON. When sending data via JSON the contentType for jQuery AJAX is application/json; charset=UTF-8

This is the request header,

POST /ajax-php/api.php HTTP/1.1  
Host: localhost:8081  
Connection: keep-alive  
Content-Length: 42  
Cache-Control: no-cache  
Pragma: no-cache  
Origin: http://localhost:8081  
X-Requested-With: XMLHttpRequest  
Content-Type: application/json; charset=UTF-8  
Accept: */*  
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.143 Safari/537.36  
Referer: http://localhost:8081/ajax-php/index.php  
Accept-Encoding: gzip,deflate,sdch  
Accept-Language: en-US,en;q=0.8,fr;q=0.6  

When PHP receives this data and looks at the content type, it’s not quite sure how to process it, so it leaves it alone. In this case the action – ‘POST’ or ‘GET’ doesn’t matter. You’ll notice that $_POST or $_GET both, are empty arrays. Now, it’s up to you to read this data and parse it.

$app_json=json_decode(file_get_contents('php://input'));

The code above, reads the data from PHP’s input stream. Since we have passed a JSON string, we decode it, which converts it to a PHP array and stores it in $app_json. If the data you send is not in a correct JSON format, $app_json will have false.

When we echo our response, we get the following on the client side,

{"GET":[],"POST":[],"JSON":{"firstname":"Abijeet","lastname":"Patro"}}

I set up a small project to illustrate what has been written here. You can find it over on my github page.

get_results PHP function not working on CentOS

There are instances where the PHP function - get_results will not work on CentOS (this maybe the case with other Linux based operating systems as well). I faced this issue while deploying a project on CentOS which was originally developed on Windows. All my INSERT, UPDATE and DELETE database statements were working properly, but bulk SELECTstatements had issues. After closer inspection I was able to narrow it down to get_results function.

While reading the documentation, I came across this on the get_results documentation page -

MySQL Native Driver Only  
Available only with mysqlnd.  

Using this post on StackOverflow I was able to determine if mysqlnd driver was actually installed and as expected it wasn't.

Posting php code from the StackOverflow post -

$mysqlnd=function_exists('mysqli_fetch_all');
if($mysqlnd) {  
   echo 'mysqlnd enabled!';
}

Here are the steps used to get the mysqlnd driver working on CentOS,

// First remove the existing MySQL driver<br></br>
yum --enablerepo=remi,remi-test remove php-mysql

// Then go ahead and install mysqlnd<br></br>
yum --enablerepo=remi,remi-test install php-mysqlnd

// Restart httpd<br></br>
/sbin/service httpd restart

// If you have phpMyAdmin, re-install it so that it uses the new MySQL driver
yum remove phpMyAdmin  
yum install phpMyAdmin  

Once the mysqlnd driver had been installed I had no issues while using the get_results function.

Tree view based file explorer for the web using jQuery.

This post assumes that the reader has a basic understanding of PHP, jQuery and jQuery $.post

Recently I had to implement a windows-esque tree view based file explorer for one of my projects at work. I ended up using this wonderful jQuery plugin to help me. In this blog I'll be going through some basic code to get it working using PHP on the server side.

To whet your appetite, here's what we'll be achieving in this blog post - A complete tree view based file explorer that feeds from a folder on the server's file system.

File tree view

So let's get started!

To be able to render a proper tree using the aciTree plugin, we'll need to send JSON from server in the following format -

[
  {
    "id": "folder_1",
    "label": "ThisisFolder1",
    "inode": true,
    "open": false,
    "icon": "folder",
    "branch": [
      {
        "id": "sub-item_x",
        "label": "ThisisFileX",
        "inode": false,
        "icon": "file"
      },
      {
        "...": "..."
      },
      {
        "...": "..."
      }
    ]
  },
  {
    "id": "file_1",
    "label": "ThisisFile1",
    "inode": false,
    "icon": "file"
  },
  {
    "...": "..."
  },
  {
    "...": "..."
  }
]

Here's the list of things that we'll be doing -

  1. Server Side Code
  2. HTML
  3. JavaScript/jQuery code to communicate with the server.
  4. Basic event handling for the aciTree plugin.

1. Server side code

Let's move onto the PHP code. Our job is to read the files from the specified folder and return a JSON structure that resembles what's shown above. If you look closely you'll observe that the JSON above is basically an array of objects of with properties as - id, label, inode, icon, open

The following class is exactly similar to that of the class received via JSON. We'll be returning an array of NodeList objects from the server.

/**
 * Represents each node in the aci tree jquery plugin
 * 
 * @author abijeet
 */
class NodeList {  
    public $id, $label, $inode, $open, $icon, $branch;
    private $openIfBranch;

    /**
     * Constructor for NodeList
     *
     * @param string $label
     *          Label of the node
     * @param boolean $open
     *          If this is a branch, should it be open
     * @param string $icon
     *          Icon for the node
     */
    public function __construct($label, $open, $id, $icon = '') {
        if ($id) {
            $this->id = $id;
        }
        $this->label = basename($label);
        $this->open = false;
        $this->openIfBranch = $open;
        $this->icon = $icon;
        $this->inode = false;
    }

    public function setBranch($branch) {
        $this->branch = $branch;
        $cntBranch = count($branch);
        if ($cntBranch > 0) {
            $this->inode = true;
            $this->label .= ' [' . $cntBranch . ']';
        }
        $this->open = $this->openIfBranch;
    }
}

Now to read the list of files and folders from a location on the server -

/**
 * Function that given a path, returns an array of nodeList
 * This can then be converted to a json format.
 * 
 * @param $path Path
 *            of the folder from which to retrieve
 * @return multitype:NodeList Returns the json tree
 */
function jsonForResTree($path) {  
    $dirArray = getAllFilesAndFolders($path);
    $nodeArray = array ();
    $node = '';
    $cnt = count($dirArray);
    for($i = 0; $i < $cnt; ++ $i) {
        $node = new NodeList($dirArray[$i], false);
        if (is_dir($dirArray[$i])) {
            // Recursion - It's a folder, get the array of nodeList for it.
            $nodeList = jsonForResTree($dirArray[$i]);
            // Add it as branch
            $node->setBranch($nodeList);
        }
        $nodeArray[] = $node;
    }
    return $nodeArray;
}

/**
 * Gets all files and folders from the specified path
 * 
 * @param unknown $path
 *            Path of the folder from where files and folders are to be retrieved
 * @return multitype:
 */
function getAllFilesAndFolders($path) {  
    if (! is_dir($path)) {
        return array ();
    }
    $path = $path . DIRECTORY_SEPARATOR . '*';
    return glob($path, GLOB_NOSORT);
}

Some code to handle the request that we will be making from the client side and then echoing the output in JSON format -

if (! empty($_POST['method'])) {  
    // Do some check before handling the POST data.
    $methodToCall = $_POST['method'];
    ob_clean();
    // Call the method requested from the client side.
    $result = call_user_func($methodToCall);
    die(json_encode($result));
}

/**
 * Function that is call by the JQUERY post.
 * 
 * @return multitype:NodeList
 */
function getJsonTree() {  
    // Folder Path from where we are going to show the tree view.
    $pathToGetAciTree = './cakephp';
    $jsonTree = jsonForResTree($pathToGetAciTree);
    return $jsonTree;
}

Okay so we have the PHP code in place. Next order of things -

  1. Server Side Code
  2. HTML
  3. JavaScript/jQuery code to communicate with the server.
  4. Basic event handling for the aciTree plugin.

2. HTML

The following HTML goes inside the body tag-

<!-- Scripts and CSS to be loaded. This will be avaliable when you download aciTree plugin -->  
<link href="css/aciTree.css" rel="stylesheet" type="text/css" />  
<link href="css/demo.css" rel="stylesheet" type="text/css" /> 

<!-- Loading jQuery -->  
<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>  
<!-- Loading the aciTree plugin -->  
<script type="text/javascript" src="js/jquery.aciPlugin.min.js"></script>  
<!-- Loading the aciTree core-->  
<script type="text/javascript" src="js/jquery.aciTree.core.js"></script>  
<!-- Loading the aciTree selectable plugin -->  
<script type="text/javascript" src="js/jquery.aciTree.selectable.js"></script> <!-- The div that will contain the ACI Tree -->  
<div id="fsTree"></div> <button id="btnGetTreeView">Get Tree View</button> <button id="btnRefreshTreeView">Refresh Tree View</button>  
<div id="currStatus"></div>  

Next, the JavaScript/jQuery to get the aciTree plugin working. This should be put inside the document's ready handler -

3. jQuery code to communicate with the server

$currStatus = $('#currStatus');
// Makes the ajax call and fetches the json for the resource tree.
$('#btnGetTreeView').click(function() {
  $("#fsTree").aciTree({
    ajax: {
      type: 'POST',
      url: 'index.php',
      data: {
        // Notice that this is the method name that
        // we wish to call on the server side.
        'method': 'getJsonTree'
      }
    }
  });
});

// Refreshing the tree view - Destroy and recreate
$('#btnRefreshTreeView').click(function() {
  var api = $('#fsTree').aciTree('api');
  api.unload(null, {
    success: function() {
      this.ajaxLoad(null);
      // Triggering the click handler of the Get Tree View button.
      // This will make the ajax call again and bind the tree...
      $('#btnGetTreeView').trigger('click');
      $currStatus.text('');
    }
  });
});

4. Event handling for the aciTree plugin

And finally a simple event handler for the aciTree that is triggered whenever a node in the tree is selected -

// ACI Tree - event handler.
$('#fsTree').on('acitree', function(event, aciApi, item, eventName, opt) {
  switch (eventName) {
    case 'focused':
    case 'selected':
      // Fired when an item in the tree is selected.
      if (item) {
        $currStatus.text('Selected - ' + item.context.innerText);
      }
  }
});

You can find the whole code here and a working copy of the project here.