使用 jquery/ajax/php/oop codeigniter 的聊天应用程序

Question

您好，这个问题与我最近发布的一个问题有关，我试图至少找到一些帮助，从而解决整个问题。 下面的代码不是我的，我必须修复它只是为了让它工作到现在的程度，但问题是 _get_chat_messages 中的算法继续执行 else 条件。这没有意义，因为Mysql中有聊天消息数据。我正在尝试使此源代码正常工作，希望它能引导我朝着正确的方向前进，自动刷新聊天消息内容，而无需强制浏览器客户端刷新或重定向标头。

是什么导致 _get_chat_messages 执行 else 条件而不考虑 if 条件。 if 条件似乎评估为 TRUE，这是没有意义的。

非常感谢任何帮助。谢谢。

//JQUERY/AJAX:

$(document).ready(function() {

setInterval(function() { get_chat_messages(); } , 2500);

$("input#chat_message").keypress(function(e) {
    if (e.which == 13) {
        $("a#submit_message").click();
        return false;
    }
});

$("#submit_message").click(function() {
    var chat_message_content = $("input#chat_message").val();
    //this if condition seems to be ignored not sure why?
    if (chat_message_content == "") { return false; }

    $.post(base_url + "chat/ajax_add_chat_message", { chat_message_content : chat_message_content, chat_id : chat_id, user_id : user_id }, function(data) {

        if (data.status == 'ok')
        { 
            var current_content = $("div#chat_viewport").html();
            $("div#chat_viewport").html(current_content + data.message_content);

        }
        else
        {
            // there was an error do something 

        }

    }, "json");

    $("input#chat_message").val("");

    return false;
});


function get_chat_messages()
{

    $.post(base_url + "chat/ajax_get_chat_messages", { chat_id : chat_id }, function(data) {

        if (data.status == 'ok')
        {
            var current_content = $("div#chat_viewport").html();

            $("div#chat_viewport").html(current_content + data.message_content);

        }
        else
        {
            // there was an error do something 

        }

    }, "json");
}

get_chat_messages();

  });

//控制器：

   class Chat extends CI_Controller {

public function __construct()
{
    parent:: __construct();
    $this->load->model('chat_model');   
}

public function index()
{
    /* send in chat id and user id */

    $this->view_data['chat_id'] = 1;

    // check they are logged in
    if (! $this->session->userdata('logged_in')) {
        redirect('user/login');
    }

    $this->view_data['user_id'] = $this->session->userdata('user_id');

    $this->session->set_userdata('last_chat_message_id_' .    $this->view_data['chat_id'], 0);

    $this->view_data['page_title'] = 'web based chat app :)';
    $this->view_data['page_content'] = 'view_chat';
    $this->load->view('view_main', $this->view_data);   
}


public function ajax_add_chat_message()
{

    /* Scalar Variable data that needs to be POST'ed to this function
     * 
     * chat_id
     * user_id
     * chat_message_content
     *       * 
     */

    $chat_id = $this->input->post('chat_id');
    $user_id = $this->input->post('user_id');
    $chat_message_content = $this->input->post('chat_message', TRUE);

    $this->chat_model->add_chat_message($chat_id, $user_id,   $chat_message_content);

    // grab and return all messages
    $this->ajax_get_chat_messages($chat_id);
}

public function ajax_get_chat_messages($chat_id)
{
    $chat_id = $this->input->post('chat_id');

    echo $this->_get_chat_messages($chat_id);
}

private function _get_chat_messages($chat_id)
{
    $last_chat_message_id = (int)$this->session->userdata('last_chat_message_id_' . $chat_id); 

    $chat_messages = $this->chat_model->get_chat_messages($chat_id, $last_chat_message_id);

    if ($chat_messages->num_rows() > 0)
    {
        // store the last chat message id
        $last_chat_message_id = $chat_messages->row($chat_messages->num_rows() - 1)->chat_message_id;

        $this->session->set_userdata('last_chat_message_id_' . $chat_id, $last_chat_message_id);

        // we have some chat let's return it

        $chat_messages_html = '<ul>';

        foreach ($chat_messages->result() as $chat_message)
        {
            $li_class = ($this->session->userdata('user_id') == $chat_message->user_id) ? 'class="by_current_user"' : '';

            $chat_messages_html .= '<li ' . $li_class . '>' . '<span class="chat_message_header">' . $chat_message->chat_message_timestamp . ' by ' . $chat_message->name . '</span><p class="message_content">' .  $chat_message->chat_message_content . '</p></li>';
        }

        $chat_messages_html .= '</ul>';

    $result = array('status' => 'ok', 'content' =>    $chat_messages_html);
        //header('Content-Type: application/json',true);
        return json_encode($result);
        exit();
    }
    else
    {
        // we have no chat yet
        $result = array('status' => 'no chat', 'content' => '');
        //header('Content-Type: application/json',true);
        return json_encode($result);
        exit();
    }
 }

  }

//型号：

    class chat_model extends CI_Model {

public function __construct()
{
    parent::__construct();
}

public function add_chat_message($chat_id, $user_id, $chat_message_content)
{
    $query_str = "INSERT INTO chat_messages (chat_id, user_id,  chat_message_content) VALUES (?, ?, ?)";

    $this->db->query($query_str, array($chat_id, $user_id, $chat_message_content));
}

public function get_chat_messages($chat_id, $last_chat_message_id = 0)
{
    $query_str = "SELECT
                cm.chat_message_id,
                cm.user_id,
                cm.chat_message_content,
                DATE_FORMAT(cm.create_date, '%D of %M %Y at %H:%i:%s') AS chat_message_timestamp,
                u.name
                FROM chat_messages cm
                JOIN users u ON cm.user_id = u.user_id
                WHERE cm.chat_id = ?
                and cm.chat_message_id > ?
                ORDER BY cm.chat_message_id ASC";

    $result = $this->db->query($query_str, array($chat_id, $last_chat_message_id));

    return $result;
}
} 

//VIEW FILE HENCE VIEW_CHAT.PHP

    <html>
    <head>
    <script type="text/javascript" src="/js/jquery-1.4.2.min.js"></script>
    <script type="text/javascript" src="<?php echo base_url() . 'public/';?>chat.js">   
    </script>
    <script type="text/javascript">

    var base_url = "<?php echo base_url();?>";

    var chat_id = "<?php echo $chat_id; ?>";
    var user_id = "<?php echo $user_id; ?>";

    </script>
    </head>
    <body>

     <style type="text/css">

     div#chat_viewport {
 font-family:Verdana, Arial, sans-serif;
 padding:5px;
 border-top:2px dashed #585858;
 min-height:300px;
 color:black;
 max-height:650px;
 overflow:auto;
 margin-bottom:10px;
 width:750px;
}

    div#chat_viewport ul {
list-style-type:none;
padding-left:10px;
  }

    div#chat_viewport ul li {
margin-top:10px;
width:85%;
  }

    span.chat_message_header {
font-size:0.7em;
font-family:"MS Trebuchet", Arial, sans-serif;
color:#547980;
 }

    p.message_content {
margin-top:0px;
margin-bottom:5px;
padding-left:10px;
margin-right:0px;
}

    input#chat_message {
margin-top:5px;
border:1px solid #585858;
width:70%;
font-size:1.2em;
margin-right:10px;
  }

   input#submit_message {
font-size:2em;
padding:5px 10px;
vertical-align:top;
margin-top:5px;
 }

    div#chat_input { margin-bottom:10px; }

    div#chat_viewport ul li.by_current_user span.chat_message_header {
color:#e9561b;
}

   </style>


  <h1>Let's do some chatting :D</h1>

  <div id="chat_viewport">

  </div>

  <div id="chat_input">
  <?php echo form_open('chat/ajax_add_chat_message'); ?>
  <input id="chat_message" name="chat_message" type="text" value="" tabindex="1" />
  <?php echo form_submit('submit_message','submit_message'); ?>
  <?php echo anchor('#', 'Say it', array('title' => 'Send this chat message', 'id' => 'submit_message'));?>
<div class="clearer"></div>
  <?php echo form_close(); ?>
  </div>
  </body>
  </html>

Answer 1

我不确定，但我感觉您从服务器收到的 json 格式不正确。看到这个：jQuery won't parse my JSON from AJAX query