文本字段显示“未定义”的 php 数据库？

Question

我正在尝试创建一个表单，当用户在一个文本字段中输入帐户代码时，帐户名称应在下一个文本字段中自动生成。数据库和表已经建立，但是当用户输入帐户代码时，帐户名称字段显示“未定义”。我是编码新手，我不确定如何解决这个问题。下面我附上了我的表单的样子，javascript 代码和 PHP 代码。 我的表单

脚本：

// onkeyup event will occur when the user 
        // release the key and calls the function
        // assigned to this event
        function GetDetail(str) {
            if (str.length == 0) {
                document.getElementById("account_name").value = "";
                return;
            }
            else {
  
                // Creates a new XMLHttpRequest object
                var xmlhttp = new XMLHttpRequest();
                xmlhttp.onreadystatechange = function () {
  
                    // Defines a function to be called when
                    // the readyState property changes
                    if (this.readyState == 4 && 
                            this.status == 200) {
                          
                        // Typical action to be performed
                        // when the document is ready
                        var myObj = JSON.parse(this.responseText);
  
                        // Returns the response data as a
                        // string and store this array in
                        // a variable assign the value 
                        // received to first name input field
                          
                        document.getElementById
                        ("account_name").value = myObj[1];
                          
                    }
                };
  
                // xhttp.open("GET", "filename", true);
                xmlhttp.open("GET", "cashVoucher.acc.php?user_id=" + str, true);
                  
                // Sends the request to the server
                xmlhttp.send();
            }
        }

PHP：

<?php
  
// Get the user id 
$account_code = $_REQUEST['account_code'];
  
// Database connection
$con = mysqli_connect("localhost", "root", "", "general_ledger_account");
  
if ($user_id !== "") {
      
    // Get corresponding first name and 
    // last name for that user id    
    $query = mysqli_query($con, "SELECT account_name FROM ledger_account WHERE account_code='$account_code'");
 

    $row = mysqli_fetch_array($query);
  
    // Get the first name
    $name = $row["account_name"];
  
   
}
  
// Store it in a array
$result = array("$name");
  
// Send in JSON encoded form
$myJSON = json_encode($result);
echo $myJSON;
?>

表格：

 <div class="form-group">
                        <label>Account Code</label>
                        <input type="text" class="form-control" id="account_code" name="account_code" placeholder="Debit or Credit Account Code" onkeyup="GetDetail(this.value)" value="">
                    </div>  
                    <div class="form-group">
                        <label>Account Name</label>
                        <input type="text" class="form-control" id="account_name" name="account_name"  placeholder="Debit or Credit Account Name" value="">
                    </div>  

Answer 1

javascript中的数组是零索引的，所以第一项的索引是0，所以代码应该是：

document.getElementById("account_name").value = myObj[0];

Answer 2

您还需要在脚本代码和 php 代码中将 user_id 替换为 account_code，并将 myObj[1] 更改为 myObj[0] 查看更新的代码

<?php


// Get the user id 
$account_code = $_REQUEST['account_code'];
  
// Database connection
$con = mysqli_connect("localhost", "root", "", "general_ledger_account");
  
if ($account_code !== "") {
      
    // Get corresponding first name and 
    // last name for that user id    
    $query = mysqli_query($con, "SELECT account_name FROM ledger_account WHERE account_code='$account_code'");
 

    $row = mysqli_fetch_array($query);
  
    // Get the first name
    $name = $row["account_name"];
  
   
}
  
// Store it in a array
$result = array("$name");
  
// Send in JSON encoded form
$myJSON = json_encode($result);
echo $myJSON;
?>

Javascript 代码

// onkeyup event will occur when the user 
    // release the key and calls the function
    // assigned to this event
    function GetDetail(str) {
        if (str.length == 0) {
            document.getElementById("account_name").value = "";
            return;
        }
        else {

            // Creates a new XMLHttpRequest object
            var xmlhttp = new XMLHttpRequest();
            xmlhttp.onreadystatechange = function () {

                // Defines a function to be called when
                // the readyState property changes
                if (this.readyState == 4 && 
                        this.status == 200) {
                      
                    // Typical action to be performed
                    // when the document is ready
                    var myObj = JSON.parse(this.responseText);

                    // Returns the response data as a
                    // string and store this array in
                    // a variable assign the value 
                    // received to first name input field
                      
                    document.getElementById
                    ("account_name").value = myObj[0];
                      
                }
            };

            // xhttp.open("GET", "filename", true);
            xmlhttp.open("GET", "test.php?account_code=" + str, true);
              
            // Sends the request to the server
            xmlhttp.send();
        }
    }