PHP打印JSON数据

Ok, here comes our server script. Let's walk through it...

First, the server needs to connect to the database. We'll do a very simple connexion:

 

<?php
////////////////////////////////////////////////////////
// DATABASE.PHP
////////////////////////////////////////////////////////
  mysql_connect("localhost", "username", "pwd") or
  die("Could not connect: " . mysql_error());
  mysql_select_db("db_name");

I'll let you fix the names for the localhost / username / pwd / db_name.

Second, we need to process the requests from Ext. We'll have Ext ask for different tasks through a $_POST var called 'task'. So, imagining that Ext will send us a $_POST['task'], all we need to do is to respond accordingly.

 

  $task = '';
  if ( isset($_POST['task'])){
    $task = $_POST['task'];   // Get this from Ext
  }
  switch($task){
    case "LISTING":              // Give the entire list
      getList();
      break;
    default:
      echo "{failure:true}";  // Simple 1-dim JSON array to tell Ext the request failed.
      break;
  }

Great... Now that that's done, we'll go ahead and go build the getList() function which will simply query our database. The only problem is that we need to supply Ext with a JSON format, and that SQL just returns an array. Well now you just have to figure out for yourself the script that will do the conversion between the two.

Ok, you don't really have to... Actually, on PHP versions 5.2 and higher, that function is already implemented. Yee... Still, we'll pretend like we're running on any version of PHP, so we'll just have to add a file called JSON.php that will do the conversion for us.

Allright, back to the code :

 

function getList() 
{
	$query = "SELECT * FROM presidents pr, parties pa WHERE pr.IDparty = pa.IDparty";
	$result = mysql_query($query);
	$nbrows = mysql_num_rows($result);	
	if($nbrows>0){
		while($rec = mysql_fetch_array($result)){
                        // render the right date format
			$rec['tookoffice']=codeDate($rec['tookoffice']);
			$rec['leftoffice']=codeDate($rec['leftoffice']); 
			$arr[] = $rec;
		}
		$jsonresult = JEncode($arr);
		echo '({"total":"'.$nbrows.'","results":'.$jsonresult.'})';
	} else {
		echo '({"total":"0", "results":""})';
	}
}

As you can see, we put everything into a big array $arr and gave that to our JEncode() function. The result, $jsonresult, is a nice JSON array that is ready to be shipped to Ext. We add the total number of results and we send everything back through the ECHO command.

Note: The ECHO command is what makes this Ext/PHP thing so easy to debug... If you don't know what I'm talking about, please download FIREBUG and use it as you go along with this tutorial.

By the way, we added a little codeDate function that simply translates a mm/dd/YYYY format to a YYYY-mm-dd format. We do this so that we can send it directly to our SQL database :

 

// Encodes a YYYY-MM-DD into a MM-DD-YYYY string
function codeDate ($date) {
	$tab = explode ("-", $date);
	$r = $tab[1]."/".$tab[2]."/".$tab[0];
	return $r;
}

Ok, we just need to write down the JEncode function and we'll be done!

 

function JEncode($arr){
    if (version_compare(PHP_VERSION,"5.2","<"))
    {    
        require_once("./JSON.php");   //if php<5.2 need JSON class
        $json = new Services_JSON();  //instantiate new json object
        $data=$json->encode($arr);    //encode the data in json format
    } else
    {
        $data = json_encode($arr);    //encode the data in json format
    }
    return $data;
}
?>