如何将获取的数据放在输入字段中-AJAX

Question

Im trying to live search or filter some data in my database using AJAX , I used the oninput event to trigger the function. But it's not working, can someone help me to find what's wrong in my code? Im just a beginner in ajax.

Here's my input field,

   <div class="form-group">
               <label for="stud_num">Student Number</label>
                <input type="text" name="stud_num" class="form-control stud_num" oninput="loadinfo()" id="stud_num" placeholder="Student Number" style="max-width:150px;" required>
        </div> 

here's my function,

  function loadinfo(){
    var stud = $("#stud_num").val();
    $.ajax({
      url:'getrecords.php',
      method:'POST',
      data:{
        "loadinfo": 1,
        "stud": stud,
      },
      success: function(data){
        $('#firstname').val(data.firstname);
      }
    });
  }

here the php code,

   if(isset($_POST['loadinfo'])){
    $stud = $_POST['stud'];

    $sql = "SELECT * FROM studmast WHERE stud_no ='$stud'";
    $result = mysqli_query($con,$sql);

       while($row = mysqli_fetch_array($result)){
                  $data[] = array(
                        'lastname' => $row['lastname'],
                        'firstname' => $row['firstname'],
                        'midname' => $row['middlename']
                        );
            }
            echo $data;
   }

Answer 1

You can't echo a php array...you need to send a data format that can easily be consumed by client and the most common nowadays is json.

Use json_encode() to convert

Try

echo json_encode($data);

And make sure to set the dataType:'json in $.ajax

Answer 2

Because I cannot reply to comments yet.. @nethken as others have stated, use json_encode. Please ensure that data is being posted to the php file in question. You can confirm this by debugging the code in developer tools. Either step through the code or alert the value before sending (javascript client-side debugging).

Next, I would var_dump($_POST['stud']) in your php file, this will confirm whether the value is getting there or not. You can see the data by going to the network traffic in your developer tools and selecting preview of the php file. If you have xDebug you can simply step through the code to debug, I'll assume you do not have it setup.