Question

我正在尝试为我的移动后端制作一个php REST API来与MySQL数据库进行交互。我已经写出以下代码来尝试从MySQL查询中检索数据：

<?php include "FILE WITH DB_INFO"; ?>
    <html>
    <body>
    <h1>Testing page</h1>
<?php

$connection = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD);

if (mysqli_connect_errno()) echo "Failed to connect to MySQL" . mysqli_connect_error();


$database = mysqli_select_db($connection, DB_DATABASE);

if (strlen($username_query)) {
    doesUsernameExist($connection, $username_query);
}

doesUsernameExist($connection, $username_query);

$username_query = $_GET['usernameToQuery'];

echo($_GET['usernameToQuery']);


function doesUsernameExist($connection, $username) {
    $u = mysqli_real_escape_string($connection, $username);

    $query = "SELECT username from users WHERE username = ('$u');";


if (!mysqli_query($connection, $query)) {
    $response = array("success" => false, "message" => mysqli_error($connection), "sqlerrno" => mysqli_errno($connection), "sqlstate" => mysqli_sqlstate($connection));
    echo json_encode($response);
} else {
    $sth = mysqli_query($connection, $query);
    $rows = array();
    while($r = mysqli_fetch_assoc($sth)) {
        $rows[] = $r;
    }
    $response = array("success" => true);
    echo json_encode($rows);
}

}
?>

这是实际请求的样子：http://my_ec2_instance/DoesUsernameExist.php?usernameToQuery=lmao。这是通过POSTMAN发送的。

因为我使用的MySQL数据库包含值为lmao的用户名，所以php函数应该返回一个非空的数组。但是json_encode($rows);行返回一个空数组[]。我究竟做错了什么。

Answer 1

您似乎在doUsernameExiste()之前和strlen之前使用变量$username_query。但是你只能在之后定义$username_query。

你应该先做好准备。把它放在你的mysqli_select_db

之后

$username_query = $_GET['usernameToQuery'];

php在尝试获取MySQL数据时返回空的GET数组

1 个答案: