Question

以下是将数据插入表格的脚本。我的问题只涉及php中的表单验证。

这是我的php代码：

<?php 
//Here I have defined an error variable for each of the variables in the project 

$nameErr = $productErr = $priceErr = $catErr = $regionErr = "";
$product_name = $product_cond = $product_price = $product_cat = $product_region = "";

$con=mysqli_connect("localhost","*****","*****","my_project");
if (mysqli_connect_errno()) 
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
} 

   // here in this elseif, I check the number of characters in the field and then it is suppose to send an error (on the same page) if it does not match

elseif (strlen($_POST['product_name']) < 5 ) {

    $productErr = "name is too short";
} 
elseif (strlen($_POST['product_name']) > 10) {

    $productErr = "name is too long";
} 
elseif (empty($_POST['product_cond'])) {
    $productErr = "product condition required";
} 
else 
{
    $sql= "INSERT INTO Product (product_name, product_cond, product_price, product_cat, product_region, email, phone_num)
          VALUES
          ('$_POST[product_name]','$_POST[product_cond]','$_POST[product_price]','$_POST[product_cat]','$_POST[product_region]','$_POST[Email]','$_POST[PhoneNumber]')";

    if (!mysqli_query($con,$sql)) 
    {
        echo 'Error: ' . mysqli_error($con);
    }
    else     
    {
        echo "1 record added";
    }
}
mysqli_close($con);
?>

这是我的html页面：

<html>
<body>
    <h3> Please enter your product information bellow: </h3>
    <form action="insert_data.php" method="post">
Product name: <input type="text" name="product_name" >

// here I added this line that is suppose to do echo the error message:

<span class="error">* <?php echo $nameErr;?></span>
Condition: 
<select name="product_cond">
  <option value="" >SELECT</option>
  <option value="Used" >Used </option>
  <option value="new" >New</option>

</select>

Category:
<select name="product_cat">
  <option value="" >SELECT</option>
  <option value="books" >books</option>
  <option value="Computers" >Computers</option>
  <option value="Hardware/Tools" >Hardware/Tools </option>
  <option value="Cars" >Cars</option>
  <option value="home Appliances" >home Appliances</option>
</select>

Region:
<select name="product_region">
  <option value="Oulu" >Oulu</option>
  <option value="Turku" >Turku</option>
  <option value="Helsinki" >Helsinki </option>
  <option value="Tornio" >Tornio</option>
  <option value="Tampere" >Tampere</option>
  <option value="Kemi" >Kemi</option>

</select>
Product price: <input type="text" name="product_price">

<input type="submit">
</form>
</body>
</html>

问题是这个方法仍然会阻止数据插入表中，但它不会给我一个错误，它只是给我一个空白屏幕。问题是什么。（我使用w3school提供的这个例子：http://www.w3schools.com/php/showphp.asp?filename=demo_form_validation_required）

Answer 1

在php中尝试以下代码：

<?php

$con=mysqli_connect("localhost","*****","*****","my_project");
if (mysqli_connect_errno()) 
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
} 

$error  =   false;
$errorMsg   =   "";

if (strlen($_POST['product_name']) < 5 ) {
    $error  =   true;
    $errorMsg. = "name is too short";
} 
elseif (strlen($_POST['product_name']) > 10) {
    $error  =   true;
    $errorMsg. = "name is too long";
} 

if (empty($_POST['product_cond'])) {
    $error  =   true;
    $errorMsg. = "product condition required<br/>";
}
if (empty($_POST['product_price'])) {
$error  =   true;
    $errorMsg. = "product price required<br/>";
}

if (empty($_POST['product_cat'])) {
$error  =   true;
    $errorMsg. = "product category required<br/>";
}

if (empty($_POST['product_region'])) {
$error  =   true;
    $errorMsg. = "product region required<br/>";
}

if (empty($_POST['email'])) {
$error  =   true;
    $errorMsg. = "email required<br/>";
}

if (empty($_POST['phone_num'])) {
$error  =   true;
    $errorMsg. = "phone required<br/>";
}


if(!$error) 
{    
    $sql= "INSERT INTO Product (product_name, product_cond, product_price, product_cat, product_region, email, phone_num)
      VALUES            ('$_POST[product_name]','$_POST[product_cond]','$_POST[product_price]','$_POST[product_cat]','$_POST[product_region]','$_POST[Email]','$_POST[PhoneNumber]')";

    if (!mysqli_query($con,$sql)) 
    {
        echo 'Error: ' . mysqli_error($con);
    }
    else     
    {
        echo "1 record added";
    }
}else{
    echo $errorMsg;
}
mysqli_close($con);
?>

Answer 2

PHP代码

<?php


    //Here I have defined an error variable for each of the variables in the project

    if (isset($_POST['product_name']) && isset($_POST['product_cond']) && isset($_POST['product_price']) && isset($_POST['product_cat']) && isset($_POST['product_region']) && isset($_POST['Email']) && isset($_POST['PhoneNumber'])) {

        $nameErr = $productErr = $priceErr = $catErr = $regionErr = "";
        $product_name = $product_cond = $product_price = $product_cat =
        $product_region = "";


        $con = mysqli_connect("localhost", "*****", "*****", "my_project");
        if
        (mysqli_connect_errno()
        ) {
            echo "Failed to connect to MySQL: " . mysqli_connect_error();
        }


        // here in this elseif, I check the number of characters in the
        field and then it is suppose to send an error(on the same page) if it
            does not match

     elseif (strlen($_POST['product_name']) < 5) {

            $productErr = "name is too short";
        }  elseif (strlen($_POST['product_name']) > 10) {

            $productErr = "name is too long";
        }  elseif (empty($_POST['product_cond'])) {
            $productErr = "product condition required";
        }

     else  {
            $sql = "INSERT INTO Product (product_name, product_cond, product_price, product_cat, product_region, email, phone_num)

               VALUES
               ('$_POST['product_name']','$_POST['product_cond']','$_POST['product_price']','$_POST['product_cat']','$_POST['product_region']','$_POST['Email']','$_POST['PhoneNumber']')";

         if (!mysqli_query($con, $sql)) {
             echo 'Error: ' . mysqli_error($con);
         } else {

             echo "1 record added";
         } } mysqli_close($con);
     }
    ?>

<强> HTML

<html>
<body>
    <h3> Please enter your product information bellow: </h3>
    <form action="insert_data.php" method="post">
Product name: <input type="text" name="product_name" pattern="[a-zA-Z]{4,9}" required>

// here I added this line that is suppose to do echo the error message:
<span class="error">* <?php echo $nameErr;?></span>
Condition:
<select name="product_cond" required>
  <option value="" >SELECT</option>
  <option value="Used" >Used </option>
  <option value="new" >New</option>

</select>

Category:
<select name="product_cat" required>
  <option value="" >SELECT</option>
  <option value="books" >books</option>
  <option value="Computers" >Computers</option>
  <option value="Hardware/Tools" >Hardware/Tools </option>
  <option value="Cars" >Cars</option>
  <option value="home Appliances" >home Appliances</option>
</select>

Region:
<select name="product_region" required>
  <option value="Oulu" >Oulu</option>
  <option value="Turku" >Turku</option>
  <option value="Helsinki" >Helsinki </option>
  <option value="Tornio" >Tornio</option>
  <option value="Tampere" >Tampere</option>
  <option value="Kemi" >Kemi</option>

</select>
Product price: <input type="text" name="product_price" pattern="[0-9]{0,5}" required>



<input type="submit">
</form>

PHP表单验证

2 个答案: