5.5.15

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。

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。

Example #1 隐藏的 HTML 表单单元

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

Note: 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。

Example #2 等待用户编辑的数据

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

Note: 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。

Example #3 URL 中的例子

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

Note: 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()

Note: 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()

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']

Note:

请求变量名中的空格被转换为下划线。

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。

Note:

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

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[]'];

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 14 notes

up
1
Jay
3 months ago
If you have a really large form, be sure to check your max_input_vars setting.  Your array[] will get truncated if it exceeds this.  http://www.php.net/manual/en/info.configuration.php#ini.max-input-vars
up
3
ciprian dot stingu at gmail dot com
2 years ago
Using jquery is even easier to send (post) data between javascript and php

<?php
//make an asynchronous request
$.post("somefile.php", {"Param1" : true, "Param2" : 1, "Param3" : "some text"},
    function(
received_data)
    {
       
//do something with received data
       
$("#some_element").html(received_data);
    });

//make a post request
$.ajax({
   
type: "POST",
   
url: "somefile.php",
   
data: {"Param1" : true, "Param2" : 1, "Param3" : "some text"},
   
success: function(received_data)
        {
//do something with received data},
   
async: false
});
?>
up
2
martellare at hotmail dot com
11 years ago
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>

===================
up
2
martellare at hotmail dot com
11 years ago
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).
up
0
bas at cipherware dot nospam dot com
11 years ago
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];
up
-4
davis at risingtiger dot net
10 years ago
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>";
}
?>
up
-5
jetboy
8 years ago
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.
up
-5
Kenn White kennwhite dot nospam at hotmail dot com
10 years ago
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
up
-5
francesco
7 years ago
Another way to pass variables from JavaScript to PHP.

<script type="text/javascript" language="JavaScript">
<!--
function getScreenResolution()
{
    return document.form.ScreenResolution.value = screen.width + "x" + screen.height;
}
//-->
</script>
<form name="form" action="screen.php?show=ok" method="post" >
<input name="ScreenResolution" type="text" size="20" maxlength="9" />
<input name="show" type="submit" value="Submit" onclick="getScreenResolution()" />
</form>
<?php
   
echo $_POST['ScreenResolution'];
?>
up
-6
dmsuperman at comcast dot net
8 years ago
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>
up
-6
dreptack at op dot pl
9 years ago
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
up
-6
vlad at vkelman dot com
10 years ago
"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.
up
-9
tchibolecafe at freemail dot hu
7 years ago
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);
  }

 
$img_path='éöüä.jpg';
  echo
'<img src="'.fs_attr($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...
up
-12
levinb at cs dot rpi dot edu
9 years ago
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];
                }
        }
}

?>
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