章 54. PHP 和 HTML

PHP 和 HTML 有很多相互作用:PHP 能生成 HTML,HTML 可以向 PHP 传递信息。在阅读这些常见问题之前,先学会怎样从 PHP 之外取得变量很重要。此主题的手册页也包括很多例子。还要仔细留意 register_globals 对你意味着什么。

1. 当我通过表单/URL 传值时需要用什么编码/解码方法?
2. 我在试用 <input type="image"> 标记,但是没有 $foo.x$foo.y 变量,它们哪去了?
3. 怎样在 HTML 的 <form> 中建立数组?
4. 怎样从可多选的 HTML 的 select multiple 标记中得到所有结果?
5. 怎样从 Javascript 传递一个变量到 PHP?

1. 当我通过表单/URL 传值时需要用什么编码/解码方法?

在几个环节上编码方式很重要。假定有 string $data,其中包含了想通过非编码方式传递的字符串,那这是相关步骤:

  • HTML 解析。要指定一个任意的字符串,必须将其放在双引号中,并用 htmlspecialchars() 处理整个值。

  • URL:URL 由几部分组成。如果希望自己的数据被当作其中一项来解释,必须urlencode() 对其编码。

例子 54-1. 隐藏的 HTML 表单单元

<?php
    
echo "<input type='hidden' value='" . htmlspecialchars($data) . "' />\n";
?>

注: urlencode() 来处理 $data 是错误的,因为是浏览器的责任来 urlencode() 数据。所有流行的浏览器都能正确处理。注意不论何种方法(例如 GET 或 POST)都会这样。不过只会在用 GET 请求时注意到这一点,因为 POST 请求通常是隐藏的。

例子 54-2. 等待用户编辑的数据

<?php
    
echo "<textarea name='mydata'>\n";
    echo
htmlspecialchars($data)."\n";
    echo
"</textarea>";
?>

注: 数据会按照预期的显示在浏览器中,因为浏览器会解释 HTML 转义符号。

当提交时,不论是 GET 或者 POST 方法,数据都会被浏览器进行 urlencode 来传输,并直接被 PHP urldecode。所以最终不需要自己处理任何 urlencoding/urldecoding,全都是自动处理的。

例子 54-3. URL 中的例子

<?php
    
echo "<a href='" . htmlspecialchars("/nextpage.php?stage=23&data=" .
        
urlencode($data)) . "'>\n";
?>

注: 事实上这在编造一个 HTML 的 GET 请求,因此需要手工对数据进行 urlencode()

注: 需要对整个 URL 进行 htmlspecialchars(),因为 URL 是作为 HTML 属性的一个值出现的。在本例中,浏览器会首先对值进行 un-htmlspecialchars(),然后再传递此 URL。PHP 将能正确理解 URL,因为对数据进行了 urlencoded()

要注意到 URL 中的 & 被替换成了 &amp;。如果忘了这一步,尽管大多数浏览器都能恢复,但也不总是这样。因此即使 URL 不是动态的,也需要对 URL 进行 htmlspecialchars()

2. 我在试用 <input type="image"> 标记,但是没有 $foo.x$foo.y 变量,它们哪去了?

当提交表单时,可以用图片代替标准的提交按钮,用类似这样的标记:
<input type="image" src="image.gif" name="foo" />
当用户点击了图片的任何部分,该表单会被发送到服务器并加上两个额外的变量:foo.xfoo.y

因为 foo.xfoo.y 在 PHP 中会成为非法的变量名,它们被自动转换成了 foo_xfoo_y。也就是用下划线代替了点。因此,可以按照在来自 PHP 之外的变量这一节中说明的那样访问这些变量。例如,$_GET['foo_x']

注: 请求变量名中的空格被转换为下划线。

3. 怎样在 HTML 的 <form> 中建立数组?

要使你的 <form> 结果被当成 array 发送到 PHP 脚本,要对 <input>,<select> 或者 <textarea> 单元这样命名:
<input name="MyArray[]" />
<input name="MyArray[]" />
<input name="MyArray[]" />
<input name="MyArray[]" />
注意变量名后的方括号,这使其成为一个数组。可以通过给不同的单元分配相同的名字来把单元分组到不同的数组里:
<input name="MyArray[]" />
<input name="MyArray[]" />
<input name="MyOtherArray[]" />
<input name="MyOtherArray[]" />
这将产生两个数组,MyArray 和 MyOtherArray,并发送给 PHP 脚本。还可以给数组分配指定的键名:
<input name="AnotherArray[]" />
<input name="AnotherArray[]" />
<input name="AnotherArray[email]" />
<input name="AnotherArray[phone]" />
AnotherArray 数组将包含键名 0,1,email 和 phone。

注: 指定数组的键名是 HTML 的可选项。如果不指定键名,则数组被按照单元在表单中出现的顺序填充。第一个例子将包含键名 0,1,2 和 3。

参见数组函数来自 PHP 之外的变量

4. 怎样从可多选的 HTML 的 select multiple 标记中得到所有结果?

可多选的 select multiple 标记是 HTML 的一个构造,允许用户从一个列表中选择多个项目。这些项目接着被传递给该表单 action 中指定的处理程序。问题是它们都会被用同样的名字传递。例如:
<select name="var" multiple="yes">
每个被选项将这样被传递到表单处理程序:
var=option1
var=option2
var=option3
每个选项将覆盖前面一个 $var 变量的内容。解决方案是用 PHP 的“表单单元数组”特性。使用方法如下:
<select name="var[]" multiple="yes">
这将告诉 PHP 将 $var 当成数组对待,每个对 var[] 的赋值都会给数组增加一项。第一项将成为 $var[0],下一个是 $var[1],等等。可以用 count() 函数来测定选择了多少个项目,必要时可以用 sort() 函数来对选项的数组进行排序。

注意如果在 JavaScript 中通过名字来引用单元,单元名字中的 [] 可能会造成问题。用表单单元中的数字序号来替代,或者将变量名用单引号括起来并用其作为单元数组的索引,例如:
variable = documents.forms[0].elements['var[]'];

5. 怎样从 Javascript 传递一个变量到 PHP?

由于 Javascript (通常情况下)是客户端技术,而 PHP (通常情况下)是服务器端技术,而且 HTTP 是一种“无状态”协议,因此两种语言之间不能直接共享变量。

但是,有可能在二者之间传递变量。一种实现的方法是用 PHP 生成 Javascript 代码,并让浏览器自动刷新,将特定的变量传递回 PHP 脚本。以下例子显示了如何这样做――让 PHP 代码取得显示屏幕的高度和宽度,通常只能在客户端这么做。

<?php
if (isset($_GET['width']) AND isset($_GET['height'])) {
  
// output the geometry variables
  
echo "Screen width is: ". $_GET['width'] ."<br />\n";
  echo
"Screen height is: ". $_GET['height'] ."<br />\n";
} else {
  
// pass the geometry variables
  // (preserve the original query string
  //   -- post variables will need to handled differently)

  
echo "<script language='javascript'>\n";
  echo
"  location.href=\"${_SERVER['SCRIPT_NAME']}?${_SERVER['QUERY_STRING']}"
            
. "&width=\" + screen.width + \"&height=\" + screen.height;\n";
  echo
"</script>\n";
  exit();
}
?>


add a note add a note User Contributed Notes
tchibolecafe at freemail dot hu
12-Aug-2006 07:34
Notes on question "1. What encoding/decoding do I need when I pass a value through a
form/URL?"

Doing an htmlspecialchars() when echoing a string as an HTML attribute value is not enough to make the string safe if you have accented (non-ASCII) characters in it. See http://www.w3.org/TR/REC-html40/appendix/notes.html#non-ascii-chars

The referred document recommends the following method to be used:

<?php
 
function fs_attr($path){
  
$retval='';
   for(
$i=0;$i<strlen($path);$i++){
    
$c=$path{$i};
     if(
ord($c)<128){
      
$retval.=$c;
     }else{
      
$retval.=urlencode(utf8_encode($c));
     }
   }
   return
htmlspecialchars($retval);
  }

 
$img_path='.jpg';
  echo
'<img src="'.fs_attr($img_path).'">';
?>

However, using utf8 encoding for path names is among others supported by Windows NT, above method fails when running for example on an Apache server on Linux.

A more fail safe way:

<?php
      
function fs_attr($path){
              
$retval='';
               for(
$i=0;$i<strlen($path);$i++){
                      
$c=$path{$i};
                       if(
ord($c)<128){
                              
$retval.=$c;
                       }else{
                               if(
PHP_OS==='WINNT')
                                      
$retval.=urlencode(utf8_encode($c));
                               else
                                      
$retval.=urlencode($c);
                       }
               }

               return
htmlspecialchars($retval);
       }
?>

There may be operating systems that want utf8 encoding, other than WINNT. Even this latter one won't work on those systems. I don't know about any possibility to determine immediately which encoding to be used on the file system of the server...
dot dot dot NO php SPAM at NO willfris dot nl SPAM dot dot dot
12-Jul-2006 06:19
@Torsten{
In http://www.w3.org/TR/xhtml1/#C_8 it says:
"Unfortunately, this constraint cannot be expressed in the XHTML 1.0 DTDs."
}

http://www.w3.org/TR/xhtml1/#C_8 also says: "When defining fragment identifiers to be backward-compatible, only strings matching the pattern [A-Za-z][A-Za-z0-9:_.-]* should be used."
I'll come back to this.

Since it's all about fragment identifiers, I can't see why using an array like arrayname[] would be used. I think arrayname[name] should be used this way the fragment identifiers stay unique.
Since [ and ] are not allowed, why not use something what is allowed and use str_replace?
example:  :_. = [ & ._: = ]  so: name="arrayname:_.name._:" OR name="arrayname:_.0._:" and offcourse also add the id attribute then for backward compatibility.
Torsten
23-Feb-2006 06:30
Section C.8 of the XHTML spec's compatability guidelines apply to the use of the name attribute as a fragment identifier.  If you check the DTD you'll find that the 'name' attribute is still defined as CDATA for form elements.
jetboy
30-Dec-2005 11:06
While previous notes stating that square brackets in the name attribute are valid in HTML 4 are correct, according to this:

http://www.w3.org/TR/xhtml1/#C_8

the type of the name attribute has been changed in XHTML 1.0, meaning that square brackets in XHTML's name attribute are not valid.

Regardless, at the time of writing, the W3C's validator doesn't pick this up on a XHTML document.
FatalError
30-Dec-2005 06:29
Actually, you can pass variables between JavaScript and PHP without even refreshing the page. To do this, you have to use AJAX, which is what dmsuperman at comcast dot net was showing in that example.
tms at infamous dot net
23-Nov-2005 10:23
Regarding drane's claim that square brackets ([]) in form input elements (as PHP uses for arrays in forms) are invalid HTML: the NAME attribute of an input element is CDATA, not NAME or ID.

Square brackets are allowed in CDATA, no problem.

(Link is mangled because it's too long:

http://www.w3.org/TR/1999/REC-html401-19991224/ interact/forms.html#h-17.4
rybasso
07-Oct-2005 05:19
If U wish to build POST request depend on form which contains select-multiple use the following js code:

var id = theForm.elements[e].id;

if (theForm.elements[e].type=='select-multiple') {
               for (f=0;f<theForm.elements[e].length;f++) {
                   if(theForm.elements[e].options[f].selected==true)
                         qs+= id+'['+f+']='+escape(theForm.elements[e].options[f].value);
                         qs+=(qs=='')?'':'&';   
               }
           }
dmsuperman at comcast dot net
11-Sep-2005 12:05
Here's a great way to pass JavaScript to PHP without even leaving the page:

<script type="text/javascript">
<!--

function xmlreq(){
  if(window.XMLHttpRequest){
   req = new XMLHttpRequest();
  }else if(window.ActiveXObject){
   req = new ActiveXObject("Microsoft.XMLHTTP");
  }
  return(req);
}
function sendPhp(url){
  var req = xmlreq();
  req.onreadystatechange = stateHandler;
  req.open("GET", url, true);
  req.send(null);
}

sendPhp("updatedatabase.php?username=blah&displayname=whatever");
//-->
</script>
fuchs at michaelfuchs dot org
09-Aug-2005 03:54
Here's a new one, which might cause problems for people:

To make my multiple select box contents accessible to both PHP and JavaScript (using getElementById()), I was using both name and id attributes - and naming them the same, for consistency:

<select multiple="multiple" id="bob[]" name="bob[]">

However, I've discovered that - for reasons unknown - using the brackets in the id causes only a single value (rather than multiple values) to get returned to the $_POST['bob'] array. What you want is:

<select multiple="multiple" id="bob" name="bob[]">

Hope this saves some time/frustration.
fib at affordit dot fr
13-Jul-2005 10:26
I was working on a small interface for a client and he wanted a template to be generated dynamically. The issue came up when I had to retrieve the values for an array of text variables. I couldn't find any tutorial to help me out so after a few investigations this is how I made it work:
 
<?php

  $line_class
=array();
 
$line_item=array();
 
   for (
$i=$rows_number;$i>0;$i--)
     {
      
$line_class[$i]=$_POST['line_class'.$i.''];
      
$line_item[$i]=$_POST['line_item'.$i.''];
     }

?>

 Hope this helps someone ... at least they will do the job sooner than I did :D.
levinb at cs dot rpi dot edu
17-Jun-2005 12:17
Well, I was working on this one project, on the assumption that I could get the values of all elements with the same name from an appropriately named array.  Well, I was *very* disappointed when I couldn't, so I made it so I did anyway.

The following script should convert the raw post data to a $_POST variable, with form data from SELECT elements and their ilk being transformed into an array.  It's heavily unoptimized, and I probably missed something, but it's relatively easy to read.  I welcome corrections.

<?php

if ($_POST) {
      
$postdata = file_get_contents('php://input');
      
      
$uglybugger = '/(?<=&)([^&=]+)(?:=([^&]*))/';
      
$matches = array();

      
preg_match_all($uglybugger, $postdata, $matches);

      
$_POST = array();

      
$match_count = count($matches[0]);
       for (
$i = 0; $i < $match_count; $i++) {
               if (!isset(
$_POST[$matches[1][$i]])) {
                      
$_POST[$matches[1][$i]] = array();
               }
              
$_POST[$matches[1][$i]][] = $matches[2][$i];
       }
      
$match_count = count($_POST);
       for (
$i = 0; $i < $match_count; $i++) {
               if (
count($_POST[$i]) == 1) {
                      
$_POST[$i] = $_POST[$i][0];
               }
       }
}

?>
lyricnz
26-May-2005 08:28
I'm surprised this is not a language function, but PHP should be able to deal with repeated values in parsing a HTTP URL.  (eg: ?foo=1&foo=2).  In the meantime you can use something like:

function getQueryBits($query,$getkey) {
  $results = array();
  foreach (split('&',$query) as $bit) {
   @list($key,$value) = split('=',$bit);
   if ($key==$getkey && $value!=NULL)
     $results[] = urldecode($value);
  }
  return $results;
}

then you can invoke this method thusly:

  getQueryBits($_SERVER['QUERY_STRING'], 'foo');

For example, on ?foo=1&foo=2&wibble&foo this will return an array with two elements, "1" and "2"
noah at noah dot org
11-May-2005 01:10
In your action, "random_picker_action.php"
shouldn't you initialize $picks? The code didn't work
for me until I added the line:
   $picks = $_REQUEST['picks'];

Here is the full random_picker_action.php

Yours,
Noah

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
   <title>How to Pass an Array from Javascript to PHP: Action Page</title>
  <!-- File: random_picker_action.php -->
</head>
<body>
<p>
<h3>How to Pass an Array from Javascript to PHP: Action Page</h3>
<?php
  $picks
= $_REQUEST['picks'];
 
$picks = urldecode(stripslashes($picks));
  echo
"<b>JavaScript said: " . $picks . "</b><p>";
 
$picks = unserialize($picks);
  if(
sizeof($picks) > 0)
  {
  
reset($picks);
   echo
"You picked the following items:<p>";
   while(
$item = each($picks))
     echo 
$item['value'] . " off, " . str_replace("_", " ", $item['key']) . "<br>";
  }
  else
   echo
"You did not pick any items<p>";
?>
</body>
</html>
richard dot prangnell at ntlworld dot com
28-Feb-2005 01:09
Further to my note posted on  26-Feb-2005 at 04:44, I have refined the JavaScript function "send_picks()" to make it more robust and universal. The original version was designed to handle string keys and +ve integer key values only; fine for the original purpose of handling random picks for a shopping cart application but it produced a mal-formed array if any -ve or non-integer key values were submitted. The new version treats both keys and key values as strings, irrespective of the data type; and we all know just how easy it is to manipulate numeric strings as numbers in PHP:-). Key values can now be anything you like; including:
"5"
"2 dozen"
"A gross"
"12.5"
"blue"
and so forth. Here's the updated code:

   <script type="text/javascript">
     function send_picks()
     {
       form1.picks.value="";
       var e, picked = 0;
       for (var i = 0 ; i < form1.elements.length - 2; i++)
       {
         e = form1.elements[i];
         if(e.value != "0" && e.value.length > 0)
         {
           e = form1.elements[i]
           picked++;
               form1.picks.value = form1.picks.value + "s:"
             + e.name.length + ":\"" + e.name + "\";s:"
             + e.value.length + ":\"" + e.value + "\";";
         }
       }
       form1.picks.value = "a:" + picked + ":{" + form1.picks.value + "}";
     }
   </script>

Note the line:
       for (var i = 0 ; i < form1.elements.length - 2; i++)
The  "-2" term is to let the function skip the last 2 elements in the form, a "hidden" input and the "submit" button. No doubt different form layouts will need a different value here.
An incidental bonus is that getting JavaScript to process a floating point input as a string rather than a number avoids the usual rounding errors that tend to turn an input such as "1.2" into a number beginning 1.199999... with about 30 places of decimals - yes, its JavaScript rather than PHP that is responsible for this kind of behaviour.
richard dot prangnell at ntlworld dot com
27-Feb-2005 12:44
The following HTML form page and PHP action page illustrate an elegant and powerful client side JavaScript to server side PHP data transfer technique perfectly matched to PHP's associative array feature. Browse to the form page and select some items by entering an INTEGER > 1 then click on Submit (Don't put strings or reals in the input fields - error trapping has been stripped out for brevity). Try selecting one, some, all or none of the items, changing the names of the form input variables (and the associated labels, for clarity!) or adding to the number of items "on offer". At no point do you need to alter either the JavaScript function or the action page in any way - just be aware that extra coding and error trapping is required - especially where the key values in the application could be something other than integers:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
   <title>How to Pass an Array from Javascript to PHP: Form Page</title>
  <!-- File: random_picker.php -->
   <script type="text/javascript">
     function send_picks()
     {
       form1.picks.value="";
       var picked = 0;
       for (var i = 0 ; i < form1.elements.length; i++)
       {
         if(form1.elements[i].value > 0)
         {
           e = form1.elements[i]
           picked++;
               form1.picks.value = form1.picks.value + "s:" + e.name.length + ":\""
           + e.name + "\";i:" + e.value + ";";

         }
       }
       form1.picks.value = "a:" + picked + ":{" + form1.picks.value + "}";
     }
   </script>
</head>
<body>
<p>
<h3 align="center">How to Pass an Array from Javascript to PHP: Form Page</h3>
<form name="form1" action="random_picker_action.php" method="post"
  onsubmit="JavaScript:send_picks()">
<table align="center" border="1" cellpadding="5" cellspacing="0">
  <tr><td>Item 13</td>
  <td><input type="text" name="item_13" value="0" size="4"></td>
  </tr>
  <tr><td>Part number 2</td>
  <td><input type="text" name="Part_number_2" value="0" size="4"></td>
  </tr>
  <tr><td>Drawing ref 327</td>
  <td><input type="text" name="Drawing_ref_327" value="0" size="4"></td>
  </tr>
  <tr><td>Organic Carrots</td>
  <td><input type="text" name="Organic_carrots" value="0" size="4"></td>
  </tr>
  <tr><td colspan="2" align="center">
     <input type="submit" value="Submit Picks">
     <input type="hidden" name="picks" value=""></td>
  </tr>
</table>
</form>
</body>
</html>

The action page for the above form page is listed below. Notice the really ingenious feature; the form variable is simply unserialized  to turn it into a fully functional PHP array! The action page doesn't need to know anything about "expected" variable names because everything PHP needs to know is right inside the array. Note also that for maximum efficiency only "picked" item data is sent. If no items at all are picked, a perfectly formed empty array is sent:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
   <title>How to Pass an Array from Javascript to PHP: Action Page</title>
  <!-- File: random_picker_action.php -->
</head>
<body>
<p>
<h3>How to Pass an Array from Javascript to PHP: Action Page</h3>
<?php
  $picks
= urldecode(stripslashes($picks));
  echo
"<b>JavaScript said: " . $picks . "</b><p>";
 
$picks = unserialize($picks);
  if(
sizeof($picks) > 0)
  {
  
reset($picks);
   echo
"You picked the following items:<p>";
   while(
$item = each($picks))
     echo 
$item['value'] . " off, " . str_replace("_", " ", $item['key']) . "<br>";
  }
  else
   echo
"You did not pick any items<p>";
?>
</body>
</html>

I hope you find this technique useful - let me know what you think - I can already hear the jaws of Java Jocks dropping!
alberto dot delatorre at gmail dot com
16-Jan-2005 03:41
Other way to make a form with array fields, and use JavaScript features on them, is use both name and id attributes on the field as:

<input type="text" name="myfield[]" id="myfield1"/>
<input type="text" name="myfield[]" id="myfield2"/>
<script language="JavaScript">
document.getElementById("myfield1");
document.getElementById("myfield2");
</script>

This is an easy way to do it. To number the fields, do a simple for structure and you have done.
dreptack at op dot pl
03-Jan-2005 04:37
I needed to post html form through image input element. But my problem was I had to use multiple image-buttons, each one for a single row of form table. Pressing the button was mention to tell script to delete this row from table and also (in the same request) save other data from the form table.
I wrote simple test-script to see what variable I should check for in a script:

I have a html document:

<form action="test.php" method="post">
<input type="image" name="varscalar" src="/images/no.gif" />
<input type="image" name="vararray[12]" src="/images/no.gif" />
</form>

And a php script:
<?php
 
if ($_POST) {
   echo
"post: <pre>"; print_r($_POST); echo '</pre>';
  }
?>

What I've discovered suprised me a lot!

After hitting on varscalar:

post:
Array
(
   [varscalar_x] => 6
   [varscalar_y] => 7
)

After hitting on upper right corner of vararray:

post:
Array
(
   [vararray] => Array
       (
           [12] => 2
       )

)

This mean when clicking on image-type input element, which name is an array, only y-part of a value is remembered.

The result is the same on: php 4.1.2 on Win98se, php 4.3.9-1 on linux
seec77 at zahav dot net dot il
22-Dec-2004 07:35
Another unfortunate result of appending "[]" to input field names to pass form data in arrays to PHP, is that people will be able to detect you are running PHP. You can tell by the whole documentation section on hiding PHP, that some people might not want the public to know their site is generated with PHP (usually for security reasons), but the "[]" will blow your cover.
So beware! If you are trying to hide PHP, you will have to stay away from passing form data as arrays!
Karen
05-Aug-2004 08:38
I am using code I got from SitePoint that uses stripslashes because of magic quotes...I finally figured out that it kept my html form select multiple field from working correctly even though I was using name="arrName[]" as the field name -- I was only getting the word array as the value, and all the things I tried there was nothing else there. The stripslashes was part of an included include file, so it took me hours to debug.  Hopefully this will help keep others from wasting time.
Jim Granger
19-Jun-2004 01:11
Kenn White wrote:

So for XHTML strict, the bottom line:
 1. form, use id, not name
 2. input, use id if you can, but if you need to use bracketed notation (for example, passing PHP arrays), i.e., foo[], you *MUST* use name for XHTML strict validation.

I don't think they are going to deprecate name entirely. For one thing, to be of any use, radio boxes and occasionally checkboxes must have the same identifying mark, in this case a name. By the rules of the DTD, id's MUST be unique. In that respect, it is probably better to not use id in input elements at all.

Of course, it's a good idea to use ids as sparingly as possible.
ppmm at wuxinan dot net
14-Jun-2004 07:11
3. How do I create arrays in a HTML <form>?

The feature is nice in the sense of simplifying programming. However, this does have side-effect. Look at this URL below:

http://www.php.net/source.php?url[]=/index.php

As a common viewpoint, exposing the absolute filesystem path in the webpage is always a bad thing. I reported this problem at bugs.php.net a few days before and I get a response saying "it's up to programmers". I think it's fair, however, webmaster should really learn to check the variables at the beginning of the script. In the above case, the PHP script should at least check like this:

if (!is_string(url)) die("with some error message");

As what I experienced, many PHP-based websites have this problem. I would think a perfect solution is that PHP does not do this automatic parsing, and when a PHP script expects an array to be posted, they would do something like

parse_http_array($_GET, "url");

only after this point, $_GET['url']) exists. Before this statement, only $_GET['url[]'] is available. Well, I am kind of too demanding I guess, but what I really intended to say is that webmaster should know this problem.
vlad at vkelman dot com
05-Jun-2004 10:04
"4.  How do I get all the results from a select multiple HTML tag?"

I think that behavior of PHP which forces to use [] after a name of 'select' control with multiple attribute specified is very unfortunate. I understand it comes from old times when registerglobals = on was commonly used. But it creates incompatibility between PHP and ASP or other server-side scripting languages. The same HTML page with 'select' control cannot post to PHP and ASP server pages, because ASP does not require [] and automatically recognize when arrays are posted.
Kenn White kennwhite dot nospam at hotmail dot com
14-Mar-2004 12:18
Concerning XHTML Strict and array notation in forms, hopefully the information below will be useful:

If I have a form, name="f", and, say, an input text box, name="user_data[Password]", then in Javascript, to reference it I would do something like:
  
var foo = f['user_data[Password]'].value;

Now, say that in making the switch to XHTML strict, I decide to fully embrace standards compliance, and change my form to id="f", and the input text box to id="user_data[Password]"

Because these have id instead of name, I discover, that all my javascript validation routines just broke.  It seems that I have to now change all my js code to something like:

document.getElementById( 'user_data[Password]' ).focus();

I test this on all the major modern browsers, and it works well.  I'm thinking, Great!  Until I try to validate said page.  It turns out that the bracket characters are invalid in id attributes.  Ack!  So I read this thread:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=
UTF-8&th=78dea36fd65d9bbe&seekm=
pqx99.19%24006.13377%40news.ca.inter.net#link11
(link needs to be spliced, sorry)

What does this mean, I start asking myself?  Do I have to abandon my goal to migrate to XHTML strict?  Transitional seems so unsatisfying.  And why bother with a technique that seems to work on most browsers, if it's broken.  Alas, there is hope.

But then I read http://www.w3.org/TR/xhtml1/#h-4.10 carefully.  It says "name" is deprecated as a form attribute, but *NOT* specifically as an attribute in form *elements*.  It seems my solution is to use "id" for the form itself, but I can legally use "name" for the individual form components, such as select and text input boxes.  I get the impression that "name" as an attribute is eventually going away completely, but in extensive testing using the W3C validator, it passes "name" on form components, as long as "id" (or, strangely, nothing) is used to denote the form itself.

So for XHTML strict, the bottom line:
 1. form, use id, not name
 2. input, use id if you can, but if you need to use bracketed notation (for example, passing PHP arrays), i.e., foo[], you *MUST* use name for XHTML strict validation.
 
-kenn

kennwhite.nospam@hotmail.com
davis at risingtiger dot net
10-Jan-2004 04:14
I thought this might be useful to fellow PHP heads like myself out there.

I recently came across a need to transfer full fledged mutli-dimensional arrays from PHP to JAVASCRIPT.

So here it is and hopefuly good things come from it.

<?php
function phparray_jscript($array, $jsarray)
{
   function
loop_through($array,$dimen,$localarray)
   {
       foreach(
$array as $key => $value)
       {
           if(
is_array($value))
           {
               echo (
$localarray.$dimen."[\"$key\"] = new Array();\n");
              
loop_through($value,($dimen."[\"".$key."\"]"),$localarray);
           }
           else
           {
               echo (
$localarray.$dimen."[\"$key\"] = \"$value\";\n");
           }
       }
   }

   echo
"<script language=\"Javascript1.1\">\n";
   echo
"var $jsarray = new Array();\n";
  
loop_through($array,"",$jsarray);
   echo
"</script>";
}
?>
email at njschedules dot com
19-Oct-2003 12:13
If you try to include an XHTML document in a PHP document, you may be including this:

<?xml version="1.0" encoding="iso-8859-1"?>

which would, of course, be read as PHP code. To avoid this problem, use:

<?php echo "<?xml version=\"1.0\" encoding=\"iso-8859-1\"?>"; ?>

Hope I can save you from those nasty warning messages :)
04-Oct-2003 06:25
Responding to the suggestion for using this line:

<form onSubmit="selection.name=selection.name + '[]'">

This did not work for me.  I had to make a function makeArray:

function makeArray(selectBox)
{
selectBox.name=selectBox.name + "[]";
}

Then, in the submit button, add this:

onClick='makeArray(this.form.selection)'

I couldn't get anything else to work.

--Rafi
jasonpb at bellsouth dot net
30-Sep-2003 02:29
Another good way for passing javascript to php without having to have a page reload is to use an img tag.

(example)
Add this where you want to collect the vars from
This can also be a .html page
<script language="javascript">
<!--//
// Define variables
if (navigator.appname != 'Netscape') {color= "color="+screen.colorDepth+"&";}
else {color = "color="+screen.pixelDepth+"&";}
avail = "avail="+screen.availwidth+"x"+screen.availheight+"&";
res = "res="+screen.width+"x"+screen.height;
isize = '" width="1" height="1" border="0"';
// Generate img tag
img = '<img name="img"
src="javascript.php?'+color+avail+res+isize+'">';
//Print it to browser
document.write(img);
//-->
</script>

Now you have the javascript vars passed along to the javascript.php page, all thats left is to add a couple lines of php code to gather the info up.

(example)
<?
// Get the vars from the javascript
$res = $_GET['res'];
$avail_res = $_GET['avail'];
$color_depth = $_GET['color'];
// Do something with the info
echo "You Screen's Resolution is $res, Your Available Screen Resolution is $avail_res, and the Color Depth on your screen is $color_depth.";
?>
Thats it!!
Hope it may help someone!
martellare at hotmail dot com
16-Mar-2003 04:28
I do not think you are right about not being able to specify something for the value attribute, but I can see where you would have thought it would fail:

A fair warning about testing to see if a variable exists...
when it comes to strings, the values '' and '0' are interpreted as false when tested this way...

<?php
if ($string) { ... }  //false for $string ==  || $string == 0
?>

The best practice for testing to see if you received a variable from the form (which in the case of a checkbox, only happens when it is checked) is to test using this...

<?php
if ( isSet($string) ) { ... } //true if and only if the variable is set
?>

The function tests to see if the variable has been set, regardless of its contents.

By the way, if anyone's curious, when you do make a checkbox without specifying the value attribute, the value sent from the form for that checkbox becomes on.  (That's for HTML in general, not PHP-specific).
josh at NO chatgris SPAM dot com
15-Jan-2003 06:18
For those of you familiar with ASP or apache aprea_request_params_as_string, this function should be very welcome to you to turn things like

<input type="hidden" name="selected_category_ids[]" value="1">
<input type="hidden" name="selected_category_ids[]" value="4">
<input type="hidden" name="selected_category_ids[]" value="5">
<input type="hidden" name="selected_category_ids[]" value="6">
<input type="hidden" name="selected_category_ids[]" value="7">

into

1, 4, 5, 6, 7

To use it, pass the name from html into this function, WITH the []'s (you can remove the log_func from this function if you want).

Basically, this functgion checks for a [] at the end of the string.  If it's there, it converts it to a comma delimited string, if not, it returns the value as normal.

<?php
function getBlindFormData( $form_name ) {
     if ( !
is_string( $form_name ) ) {
      
$this->{$this->log_func} ( "File: %s. Line: %d. \$form_name is NOT a string.", __FILE__, __LINE__ );
   }

  
$offs = strlen( $form_name ) - 2;
   if (
strpos ( $form_name, "[]", $offs ) === $offs ) {
      
$form_name = substr( $form_name, 0, $offs );
      
$isarray = 1;
   } else {
      
$isarray = 0;
   }

   if ( isset(
$_GET[$form_name] ) ) {
      
$request = $_GET[$form_name];
   }

   if ( isset(
$_POST[$form_name] ) ) {
      
$request = $_POST[$form_name];
   }

  
$ret = NULL;
   if ( isset(
$request ) ) {
       if (
$isarray ) {
      
$ret = $request[0];
       for (
$i = 1; $i < count( $request ); $i++ ) {
        
$ret .= ", ".$request[$i];
       }
     } else {
      
$ret = $request;
     }
   }

   return
$ret;
  }
?>

Usage could be as follows

To select a comma delimited list of values.

<?php
$sql
= sprintf( "DELETE FROM categories\n"
                    
.    "  WHERE category_id IN ( %s );\n"

                    
, $wrapper->getRequiredFormData( "selected_category_ids[]" ) );
?>

or just $wrapper->getOptionalFormData( "category_id" ); for retrieval of a normal http variable.

Any questions, problems, bugs you find in this email me at the abvoe email address. (remove the NO before chatgris and the SPAM after chatgris etc.)
martellare at hotmail dot com
27-Nov-2002 03:25
A JavaScript Note: Using element indexes to reference form elements can cause problems when you want to add new elements to your form; it can shift the indexes of the elements that are already there.

For example, You've got an array of checkboxes that exist at the beginning of a form:
===================

<FORM>
   <INPUT type="checkbox" name="fruits[]" value="apple">apple
   <INPUT type="checkbox" name="fruits[]" value="orange">orange
   <INPUT type="checkbox" name="fruits[]" value="banana">banana
</FORM>

===================
... These elements could be referenced in JavaScript like so:
===================

<SCRIPT language="JavaScript" type="text/javascript">
<!--
   var index = 0; //could be 1 or 2 as well
   alert(document.forms[0].elements[index]);
//-->
</SCRIPT>

===================
However, if you added a new textbox before these elements, the checkboxes indexes become 1 - 3 instead of 0 - 2;  That can mess up what ever code you create depending on those indexes.

Instead, try referencing your html arrays in JavaScript this way.  I know it works in Netscape 4 & IE 6, I hope it to some extent is universal...
===================

<SCRIPT language="JavaScript" type="text/javascript">
<!--
   var message = "";
   for (var i = 0; i < document.forms[0].elements['fruits[]'].length; i++)
   {
       message += "events[" + i + "]: " + document.forms[0].elements['fruits[]'][i].value + "\n";
   }
   alert(message);
//-->
</SCRIPT>

===================
karatidt at web dot de
18-Nov-2002 04:57
this code selects all elements with javascript
and hands them over to an array in php *sorry my english is not good*

javascript:

<script language="JavaScript">
<!--
function SelectAll(combo)
 {
   for (var i=0;i<combo.options.length;i++)
   {
     combo.options[i].selected=true;
   }
 }
//-->
</script>

html code:
<form name="form" action="<?php echo $_SERVER["PHP_SELF"]; ?>" method="post">
<select name="auswahl[]" size="10" multiple>
<option value="bill@ms.com">Bill Gates</option>
<option value="bill@unemployed.com">Bill Clinton</option>
<option value="bart@brat.com">Bart Simpson</option>
<option value="oj@free.com">OJ Simpson</option>
<option value="j@nbc.com">Jay Leno</option>
</select>

<input type="submit" name="submit1"  value="OK" onclick="SelectAll(document.form.elements['auswahl[]'])">
</form>

php code:

$auswahl = $_POST["auswahl"];
      
foreach ($auswahl as $value)
   {
       echo $value."<br>";
   }
bas at cipherware dot nospam dot com
18-Oct-2002 12:52
Ad 3. "How do I create arrays in a HTML <form>?":

You may have problems to access form elements, which have [] in their name, from JavaScript. The following syntax works in IE and Mozilla (Netscape).

index = 0;
theForm = document.forms[0];
theTextField = theForm['elementName[]'][index];
hjncom at hjncom dot net
25-May-2002 06:30
I think '[' and ']' are valid characters for name attributes.

http://www.w3.org/TR/html401/interact/forms.html#h-17.4
-> InputType of 'name' attribute is 'CDATA'(not 'NAME' type)

http://www.w3.org/TR/html401/types.html#h-6.2
-> about CDATA('name' attribute is not 'NAME' type!)
...CDATA is a sequence of characters from the document character set and may include character entities...

http://www.w3.org/TR/html401/sgml/entities.html
--> about character entity references in HTML 4
([ - &#91, ] - &#93)