为什么在以PHP格式提交数据之前会发生此验证错误？

I'm using a PHP form to forward data to an email address. Everything seems to work fine except the the error message ["You have not entered an email"] appears when the page is loaded, before any input from the user is entered, rather than through validation when submitted.

The form is here http://www.soulwatt.com/contact.php

Note: I found this PHP code online after doing a search on how to forward data to email, so it is not mine. Please excuse the lack of proper code formatting.

<?php 
 $to = $_REQUEST['sendto'] ; 
 $from = $_REQUEST['Email'] ; 
 $name = $_REQUEST['Name'] ; 
 $headers = "From: $from"; 
 $subject = "soulwatt.com Contact Data!!"; 

 $fields = array(); 
 $fields{"Name"} = "Name"; 
 $fields{"Company"} = "Company"; 
 $fields{"Email"} = "Email"; 
 $fields{"Phone"} = "Phone"; 
 $fields{"list"} = "Mailing List"; 
 $fields{"Comments"} = "Comments"; 

 $body = "Soul Watt has received the following information:

";

 foreach($fields as $a => $b)   {
    $body .= sprintf("%20s: %s
",$b,$_REQUEST[$a]);
    } 

 $headers2 = "From: noreply@soulwatt.com";
 $subject2 = "Thank you for contacting Soul Watt!"; 
 $autoreply = "Thank you for contacting us. Somebody will get back to you as soon as possible, usualy within 48 hours. If you have any more questions, please consult our website at www.soulwatt.com";

 if($from == '') {
      print "You have not entered an email. Please enter your email and try again.";
      } 
 else {

 if($name == '') {
      print "You have not entered a name.<br />Please enter your name and try again.";
      } 

 else { 
 $send = mail($to, $subject, $body, $headers); 
 $send2 = mail($from, $subject2, $autoreply, $headers2);

 if($send)  {
     print "<p><span>THANK YOU FOR CONTACTING US!</span></p>";
     print "<p><span>Someone will get back to you as soon as possible, usually within 48 hours. If you need immediate assistance regarding booking Soul Watt, please call Randy at (828) 729-3199.</span></p>";
     }

 else  {
     print "<p><span>We encountered an error sending your mail, please notify webmaster@soulwatt.com</span></p>";
     } 
 }
}?>

Thanks for your help!

These 2 lines:

$from = $_REQUEST['Email'] ; 
if($from == '') {
   print "You have not entered an email. Please enter your email and try again.";
}

Mean that you check the email request (POST and GET) key. The first time you load this page this WILL be empty. You could add a check if there was a POST at all, for instance if there was submitted.

To be honest, there might a lot of problems with your code: a user can add all sorts of stuff in there, probably even add stuff in the headers to add 'to' fields and all.. You might be making a spam-machine here. This part: $headers = "From: $from"; just adds the request field FROM in your headers....

Does your form fields have the same name that you're checking?

I mean for

$from = $_REQUEST['Email'];

You should have

<input type='text' name='Email' /> <!-- Note the Capital E -->

I add my comments here:

Use $_POST or $_GET. Avoid $_REQUEST. That way you've more controll over your app.

Also, don't check emptiness with =="" try empty($from)

You'd want to wrap your validation section in

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    ... do validation here ...
}

... print form here ...

That will only run the validation code AFTER you submit the form. As it stands now, it's running each time the page is loaded, so of course there's no form data to validate the first time around.

OK So if the form is on http://www.soulwatt.com/contact.php and you have

<form method="post" action="contact.php" name="contact_form" id="contact_form">

action="contact.php" : That means it is proccessing the form on the same address so you will see the results of the form processing on the same page, and since the form is empty, and you're checking it regardless of it having been posted or not, you get that error