php - 需要帮助将默认文本值插入 mysql

Question

最终网络开发人员，我得到了另一个团队完成的 CMS，我必须链接到我的前端。我做了一些修改，但由于我缺乏 php 知识，我在这里遇到了一些问题。

我的用户可以填写表格，其中 1 个文本字段要求提供照片链接。我想检查输入的值是否不等于我想要的，然后我将查询插入默认头像照片链接到mysql进行处理。

我在 php 上尝试过的代码

// check if the variable $photo is empty, if it is, insert the default image link
if($photo = ""){
    $photo="images/avatarDefault.png";
}

似乎不起作用

<?php
if($_SERVER["REQUEST_METHOD"] === "POST")
{
    //Used to establish connection with the database
    include 'dbAuthen.php';
    if (mysqli_connect_errno())
    {
        echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }
    else
    {

        //Used to Validate User input
        $valid = true;

        //Getting Data from the POST
        $username = sanitizeInput($_POST['username']);
        $displayname = sanitizeInput($_POST['displayname']);
        $password = sanitizeInput($_POST['password']);

        //hash the password using Bcrypt - this is to prevent 
        //incompatibility from using PASSWORD_DEFAULT when the default PHP hashing algorithm is changed from bcrypt  
        $hashed_password = password_hash($password, PASSWORD_BCRYPT);

        //Determining Type of the User
        //if B - User is student
        //if A - User is adin
        if($_POST['type'] == 'true')
            $type = 'B';
        else
            $type = 'A';

        $email = sanitizeInput($_POST['email']);
        $tutorGroup = sanitizeInput($_POST['tutorGroup']);
        $courseID = sanitizeInput($_POST['courseID']);
        $description = sanitizeInput($_POST['desc']);
        $courseYear = date("Y");
        $website = sanitizeInput($_POST['website']);
        $skillSets = sanitizeInput($_POST['skillSets']);
        $specialisation = sanitizeInput($_POST['specialisation']);
        $photo = sanitizeInput($_POST['photo']);

        // this is what i tried, checking if the value entered is empty, but doesn't work
        if($photo = ""){
            $photo="images/avatarDefault.png";
        }

        $resume = sanitizeInput($_POST['resume']);

        //Validation for Username
        $sql = "SELECT * FROM Users WHERE UserID= '$username'";
        if (mysqli_num_rows(mysqli_query($con,$sql)) > 0){
            echo 'User already exists! Please Change the Username!<br>';
            $valid = false;
        }

        if($valid){
            //Incomplete SQL Query
            $sql = "INSERT INTO Users
             VALUES ('$username','$displayname','$hashed_password','$type','$email', '$tutorGroup', ";

            //Conditionally Concatenate Values
            if(empty($courseID))
            {
                $sql = $sql . "NULL";
            }
            else
            {
                $sql = $sql . " '$courseID' ";
            }

            //Completed SQL Query
            $sql = $sql . ", '$description', '$skillSets', '$specialisation', '$website', '$courseYear', '$photo',  '$resume', DEFAULT)";

            //retval from the SQL Query
            if (!mysqli_query($con,$sql))
            {
                echo '*Error*: '. mysqli_error($con);
            }
            else
            {
                echo "*Success*: User Added!";
            }
        }

        //if student create folder for them
        if ($type == 'B')
        {
            //Store current reporting error
            $oldErrorReporting = error_reporting();

            //Remove E_WARNING from current error reporting level to prevent users from seeing code
            error_reporting($oldErrorReporting ^ E_WARNING);

            //Set current reporting error();
            error_reporting($oldErrorReporting);
        }

        mysqli_close($con);
    }
}
function sanitizeInput($data)
{
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}
?>

我尝试在mysql上找到一种插入默认值的方法，但这似乎不可能，所以我别无选择，只能通过php查询插入。

我有逻辑，但由于缺乏知识，我不确定如何在 php 上实现，我正在考虑检查 1) 如果照片链接没有.png/.jpg字样，$photo != ".png" 2)如果照片链接长度太低$.photo.length < 10

有人可以帮我查看代码并告诉我我做错了什么吗？谢谢!

Answer 1

使用默认值的一个非常简单的方法可能是:

$photo = isset($photo) ? $photo : 'images/avatarDefault.png' ;

它的工作原理是，它首先询问照片是否已设置，如果是，则使用所有准备好的插入值，否则插入默认值，

另一种(非常相似)的使用方法:

$photo = !empty($photo) ? $photo : 'images/avatarDefault.png' ;

更新

检查它是否包含某个“扩展名”将是一个简单的重写

$photo = preg_match('#\b(.jpg|.png)\b#', $photo ) ? $photo : "images/avatarDefault.png" ;

这样它会检查 $photo 中的文本/图像链接是否包含 .png 文件类型，如果不包含，则会插入默认图像