Retrieving a JSON result

Question

Hi I have used a code snippet from a tutorial for a chat application all of its scripts are working fine but after I tweak it to make the code work based on my requirements almost all of the scripts are working except for retrieving the conversation

The error I'm having is it doesn't retrieve the conversation from my database

here is the modified script

 //Create the JSON response.
$json = '{"messages": {';
//Check to ensure the user is in a chat room.
if(!isset($_GET['chat'])) {

    $json .= '"message":[ {';
    $json .= '"id":  "0",
                "user": "Admin",
                "text": "You are not currently in a chat session.  <a href="">Enter a chat session here</a>",
                "time": "' . date('h:i') . '"
            }]';
} else {
    $con3 = new PDO("mysql:host=". db_host .";dbname=db", db_username , db_password);
    $con3->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );

    $con4 = new PDO("mysql:host=". db_host .";dbname=chat_db", db_username , db_password);
    $con4->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
    $sql5 = "SELECT * FROM users WHERE id = :rid LIMIT 1";
    $stmt6=$con4->prepare($sql5);
    $stmt6->bindValue( 'rid',$_POST['rid'], PDO::PARAM_STR);
    $stmt6->execute();
        foreach($stmt6->fetchAll()as $res)
            {
                $usern = $res['username'];
                $user_lvl = $res['ulvl'];
            }

    $comb = $usern . $_POST['name'];

      //Validation if msgid exists before creating a new table on the 2nd database
      $sql6="SELECT msgid FROM thread WHERE combination1=:msgids OR combination2=:submsgids LIMIT 1";
      $msg_id = $con4->prepare($sql6);
      $msg_id->bindParam(':msgids', $comb, PDO::PARAM_STR);
      $msg_id->bindParam(':submsgids', $comb, PDO::PARAM_STR);
      $msg_id->execute();
      $msgd = $msg_id->fetchColumn();
      $tbpre = $msgd . "chat_conversation";
    $sql7 = "SELECT msgid, message_content, username , message_time FROM $tblpre WHERE msgid=:chat";

    $stmt7=$con3->prepare($sql7);
    $stmt7->bindValue( ':chat', $msgd, PDO::PARAM_STR);
    $stmt7->execute();

    $message_query = $stmt7;
    //Loop through each message and create an XML message node for each.
    if(count($message_query) > 0) {
        $json .= '"message":[ ';    
        while($message_array = $stmt7->fetch(PDO::FETCH_ASSOC)) {
            $json .= '{';
            $json .= '"id":  "' . $message_array['msgid'] . '",
                        "user": "' . htmlspecialchars($message_array['username']) . '",
                        "text": "' . htmlspecialchars($message_array['message_content']) . '",
                        "time": "' . $message_array['message_time'] . '"
                    },';
        }
        $json .= ']';
    } else {
        //Send an empty message to avoid a Javascript error when we check for message lenght in the loop.
        $json .= '"message":[]';
    }

}

//Close our response

$json .= '}}';
echo $json;

Here is the code for calling this script

    //Gets the current messages from the server
        function getChatText() {
            if (receiveReq.readyState == 4 || receiveReq.readyState == 0) {
                receiveReq.open("GET", 'includes/getChat.php?chat='+uid+'&last=' + lastMessage, true);
                receiveReq.onreadystatechange = handleReceiveChat; 
                receiveReq.send(null);
            }           
        }
        function sendChatText() {

            if (sendReq.readyState == 4 || sendReq.readyState == 0) {
                sendReq.open("POST", 'includes/getChat.php?last=' + lastMessage, true);
                sendReq.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
                sendReq.onreadystatechange = handleSendChat; 
                var param = 'message=' + document.getElementById('txtA').value;
                param += '&name='+user;
                param += '&uid='+uid;
                param += '&rid='+document.getElementById('trg').value;
                sendReq.send(param);
                document.getElementById('txtA').value = '';
            }                           
        }
    //When our message has been sent, update our page.
        function handleSendChat() {
            //Clear out the existing timer so we don't have 
            //multiple timer instances running.
            clearInterval(mTimer);
            getChatText();

        }
        function handleReceiveChat() {
            if (receiveReq.readyState == 4) {
                //Get a reference to our chat container div for easy access
                var chat_div = document.getElementById('clog');


                var response = eval("(" + receiveReq.responseText + ")");
                for(i=0;i < response.messages.message.length; i++) {
                    chat_div.innerHTML += response.messages.message[i].user;
                    chat_div.innerHTML += '&nbsp;&nbsp;<font class="chat_time">' +  response.messages.message[i].time + '</font><br />';
                    chat_div.innerHTML += response.messages.message[i].text + '<br />';
                    chat_div.scrollTop = chat_div.scrollHeight;
                    lastMessage = response.messages.message[i].id;
                }
                mTimer = setTimeout('getChatText();',20000); //Refresh our chat in 2 seconds
            }
        }

Am I missing something here or doing something wrong?

Answer 1

You should rewrite using json_encode:

$messages = array();
//Check to ensure the user is in a chat room.
if(!isset($_GET['chat'])) {
    $message_object = (object) array(
        "id"=>"0",
        "user"=>"Admin",
        "text"=>"You are not currently in a chat session.  <a href=\"\">Enter a chat session here</a>",
        "time"=>date('h:i')
    );
    $messages[] = (object) array("message"=>$message_object);
} else {
    $con3 = new PDO("mysql:host=". db_host .";dbname=db", db_username , db_password);
    $con3->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );

    $con4 = new PDO("mysql:host=". db_host .";dbname=chat_db", db_username , db_password);
    $con4->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
    $sql5 = "SELECT * FROM users WHERE id = :rid LIMIT 1";
    $stmt6=$con4->prepare($sql5);
    $stmt6->bindValue( 'rid',$_POST['rid'], PDO::PARAM_STR);
    $stmt6->execute();
        foreach($stmt6->fetchAll()as $res)
            {
                $usern = $res['username'];
                $user_lvl = $res['ulvl'];
            }

    $comb = $usern . $_POST['name'];

    //Validation if msgid exists before creating a new table on the 2nd database
    $sql6="SELECT msgid FROM thread WHERE combination1=:msgids OR combination2=:submsgids LIMIT 1";
    $msg_id = $con4->prepare($sql6);
    $msg_id->bindParam(':msgids', $comb, PDO::PARAM_STR);
    $msg_id->bindParam(':submsgids', $comb, PDO::PARAM_STR);
    $msg_id->execute();
    $msgd = $msg_id->fetchColumn();
    $tbpre = $msgd . "chat_conversation";
    $sql7 = "SELECT msgid, message_content, username , message_time FROM $tblpre WHERE msgid=:chat";

    $stmt7=$con3->prepare($sql7);
    $stmt7->bindValue( ':chat', $msgd, PDO::PARAM_STR);
    $stmt7->execute();

    $message_query = $stmt7;
    //Loop through each message and create an XML message node for each.
    if(count($message_query) > 0) {
        $message_object = (object) array(
            "id"=>$message_array['msgid'],
            "user"=>htmlspecialchars($message_array['username']),
            "text"=>htmlspecialchars($message_array['message_content']),
            "time"=>$message_array['message_time'
        );
        $messages[] = (object) array("message"=>$message_object);
    } else {
        //Send an empty message to avoid a Javascript error when we check for message lenght in the loop.
        $messages[] = (object) array("message"=>array());
    }

}

//Close our response
$result = (object) array('messages'=>$messages);
$json = json_encode($result);
echo $json;