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Monday 6 July 2015

Abstract class in PHP:


  •     Abstract Class  contains only declare the method's signature, they can't define the implementation.
    •     Abstraction class are defined using the keyword abstract .
    •     Abstract Class is not possible to implement multiple inheritance.
    •     Latest version of PHP 5 has introduces abstract classes and methods.
    •     Classes defined as abstract , we are unable to create the object ( may not instantiated ).


    •     we can extend the Abstract class, by using extends operator.
    •     we can inherit only one abstract class at one time extending.
    •     Any class that contains one abstract method must also be declare as abstract.
    •     All methods marked as abstract in the parent's class, declaration must be defined by the   child.
    •     Additionally, these methods must be defined with the same (or a less restricted) visibility           (Public,Protected & private).
    •     Type hint & number of parameter must be match between parent & child class.

      Related Posts:


    Wednesday 13 May 2015

    What is JSON?

    JavaScript Object Notation (JSON) is a lightweight data-interchange format inspired by the object literals of JavaScript. 

    JSON values can consist of:

    •   objects (collections of name-value pairs)
    •   arrays (ordered lists of values)
    •   strings (in double quotes)
    •   numbers
    •   true, false, or null

    JSON is language independent.

    JSON with PHP?

       After PHP Version 5.2.0, JSON extension is decodes and encodes functionalities as default.

    • Json_encode     - returns the JSON representation of values
    • Json_decode     - Decodes the JSON String
    • Json_last_error - Returns the last error occured.

    JSON Syntax and Rules?

       JSON syntax is derived from JavaScript object notation syntax:


    • Data is in name/value pairs
    • Data is separated by commas
    • Curly braces hold objects
    • Square brackets hold arrays

    JSON Example

        This example is simple phone number validation and once phone number has validated , it will be sent this php page, there we are using the json format related encode data.

    Html Page:
      
    <html>
    <head>
    <title>JSON Example in Php</title>
    <script src="js/jquery-1.11.0.min.js"></script>
    </head>
    <body>
    <h1>Json Basic Example</h1>
    <form name="phone-form" method="post" onsubmit="return validation();">
     <input type="text" name="phone" id="phone" value="" >
     <input type="submit" value="submit" >
    </form>
    <div id="outputDisplay"></div>
    
    
    

    Javascript Function


    <script>
    function validation(value){ 
     //Phone Number Validations
     var phone   = $('#phone').val();
     var specialDigitPattern  = /[~`!@#\$%\^&\*()\-_\+=|\\{}\[\]:;"'<>,\?\/\.0123456789]/;
     //var mailvalidateregex  = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/;  email validation
     if(phone == ""){
      alert("Please enter the phone ");
      return false;
     }else if(isNaN(phone)){
      alert('Please Enter Valid Phone Number');
      return false;
     }
     
     var postdata  = 'phone='+phone;
     var url   = 'testphone.php?phone='+phone;
     
     $.ajax({
      type  : "POST",
      url   : url, 
      data  : postdata,
      dataType : "json",
      success  : phonestatus_check,
     });
     return false;
    }
    
    function phonestatus_check(response){
     if(response.status == 1){
      alert('success');
      $("#outputDisplay").css("color","green");
      $("#outputDisplay").html(response.message);
     }else{
      alert('failure');
      return false;
     }
    }
    //ends
    </script>
    
    
    
    
    

    Php Page:

    <?php
     if(isset($_POST['phone'])){
      $phonenumber = $_POST['phone'];
      $responsearray = array();$responsestatus = '1';
      if($responsestatus == 1){
          $responsearray = array('status' => 1,'message'=> 'Thanks for submitting the Phone Number');
      }else{
       $responsearray = array('status' => 0,'message'=> 'failure');
      }
      echo json_encode($responsearray);
      /* $json = json_encode($responsearray);
      if($_GET['jsoncallback'])
       exit("{$_GET['jsoncallback']}($json)"); */
     }
    ?>
    

    Friday 1 May 2015

    Nginx: 413 Request Entity Too Large Error and Solution

      My application is running nginx as a frond end to php based Apache server. My applicatio lets user upload images upto 2MB in size. When users trying to upload 1.5MB+ size image file using nginx reverse proxy, they are getting the following error on screen:


        Nginx 413 Request Entity Too Large

    You need to configure both nginx and php to allow upload size.

    Nginx configuration:
    
    The client_max_body_size directive assigns the maximum accepted body size of client 
     request, indicated by the line Content-Length in the header of request.
    
    If size is greater the given one, then the client gets the error "Request Entity Too Large" 
    (413). To fix this issue edit your nginx.conf.
      
    Open the Terminal or login to the remote server using ssh client. 
    Type the following command to edit your nginx.conf using a text editor such as vi or joe:
    
     
    # vi /etc/nginx/nginx.conf
     
    OR 
     
    # vi /usr/local/nginx/conf/nginx.conf
    Add the following line to http or server or location context to increase 
     the size limit 
     in nginx.conf, enter:
    
    # set client body size to 2M #
    client_max_body_size 2M;
     
    
    Save and close the file. Reload the nginx webserver, enter:
    # /usr/local/nginx/sbin/nginx -s reload
    OR
    # /sbin/nginx -s reload
    OR use the following on RHEL/CentOS/Debian/Ubuntu Linux:
    # service nginx reload 
     
     

    PHP configuration (optional):
    
    
    
    Your php installation also put limits on upload file size. Edit php.ini and set the following directives ;This sets the maximum amount of memory in bytes that a script is allowed
    to allocate memory_limit = 32M ;The maximum size of an uploaded file. upload_max_filesize = 2M ;Sets max size of post data allowed.This setting also affects file upload.
    To upload large files, this value must be larger than upload_max_filesize post_max_size = 3M Save and close the file. Make sure you reload/restart back-end apache or
    nginx web server as per your setup


    Wednesday 1 April 2015

    Cookies are stored in browser as a text file format.It is stored limit amount of data.It is only allowing 4kb[4096bytes].It is not holding the multiple variable in cookies.

    we can accessing the cookies values in easily.So it is less secure.The setcookie() function must appear BEFORE the <html> tag.

    Sessions are stored in server side.It is stored unlimit amount of data.It is holding the multiple variable in sessions. we cannot accessing the cookies values in easily.So it is more secure.

    Cookies

    Sessions

    Cookies are stored in browser as
    text file format.

    Sessions are stored in server side.

    It is stored limit amount of data.
    It is only allowing 4kb[4096bytes]

    It is stored unlimit amount of data.

    It is not holding the multiple variable
     in cookies.

    It is holding the multiple variable
     in sessions.

    we can accessing the cookies values
    in easily.
    So it is less secure.
     The setcookie() function must
     appear BEFORE the <html> tag

    we cannot accessing the cookies
    values in easily.
    So it is more secure.

    Destroy Cookies:

     1. if we Closing the browsers at the time
     cookies values destoryed.
     2. setting the cookie time to expire the cookie.

    Destroy Sessions :

     1. using unset() session,we will
    destroyed the sessions.
     2. using session_destory(), we we will
    destroyed the sessions.

    
    
    Example:

    <?php
     
      setcookie(name, value, expire, 
    path,domain, secure, httponly);

    
    
      $cookie_uame = "codingslover";

    
    
      $cookie_uvalue= "website";

    
    
      //set cookies for 1 hour time
      setcookie($cookie_uname,
    $cookie_uvalue3600, "/");

    
    
      //expire cookies
    setcookie($cookie_uname,"",-3600);

    ?>
       
    
    
    
    
    Example:

    <?php
        
    session_start();
    
    //session variable
    $_SESSION['testvaraible'] = 'Codings';
     
    //destroyed the entire sessions
    session_destroy(); //Destroyed the session 
    variable "testvaraible".
    unset($_SESSION['testvaraible']);
    ?>