我的jQuery，AJAX调用在从PHP函数有效返回格式良好的JSON数据时获得null响应

Question

I have checked the logs of my PHP function and I have correctly formatted JSON data that I am returning from the method. The AJAX is calling it and returning, getting a null value for the response variable. Any Ideas? Here is the AJAX code:

$.ajax({
       type: "POST",
       url: "index.php/controllerFile/get_standby",
       data: 'id=' + $(this).attr('id'),
       success: function(response){  


             console.log('response is: ' + response); //It is null here
         $.colorbox({'href':'index.php/config/view/standby' + response.urlData,'width':1000,'title':'Standby People'});         
       },

       dataType:'json'
     });

Here is the PHP function:

function get_standby()
    {

        $id = $this->input->post('id');

        $this->load->model('teetime');
        $url['urlData'] = ($this->teetime->get_standby_by_id($id));

        $printing = json_encode($url);
        log_message('error', 'JSON ' . $printing);
        return $printing;

    }

Answer 1

I would suggest opening up Developer Tools in Chrome (View > Developer > Developer Tools) and selecting the Network tab. When your AJAX post request is made, it should add an entry there (the "Path" column should be "index.php/controllerFile/get_standby" and the "Method" column should have "POST"). Click the row for the request and check the Response tab to make sure your JSON is there.

If the response is empty, your problem is with your PHP code (you might not be printing the JSON returned from that function to the page). Otherwise, it would seemingly be a problem with your JavaScript.

Answer 2

尝试在PHP中使用echo而不是return。

echo $printing;