What method should I use to encode hidden a form field value? Assume that I am storing text like this:
This is a "really" long string with 'quotes' and special characters (~!##$%^&*()_+{}), which might have a random quote (") in the middle of it, making the HTML invalid.
We are using ASP.net to set the value:
<input type="hidden" value="<%= Model.UnencodedTextData %>" name="askingForTrouble" />
I believe if we HTML encoded it, it would solve the problem, but this form will be posted to another application, which we do not have control over. So will the receiving application (Marketo) automatically know how to decode this?
Thank you.
Marketo developer evangelist here. Before posting to Marketo, it is best to use HTML URL encoding for special characters. For example, the JavaScript code sample below would URL encode "&" and "%" characters.
function htmlEscape(str) {
return String(str)
.replace(/&/g, '%26')
.replace(/%/g, '%20');
}
I have a strange problem:
In the database, I have a literal ampersand lt semicolon:
<div
whenever its printed into a html textarea tag, the source code of the page shows the > as >.
How do I stop this decoding?
You can't stop entities being decoded in a textarea since the content of a textarea is not (unlike a script or style element) intrinsic CDATA, even though error recovery may sometimes give the impression that it is.
The definition of the textarea element is:
<!ELEMENT TEXTAREA - - (#PCDATA) -- multi-line text field -->
i.e. it contains PCDATA which is described as:
Document text (indicated by the SGML construct "#PCDATA"). Text may contain character references. Recall that these begin with & and end with a semicolon (e.g., Hergé's adventures of Tintin contains the character entity reference for the e acute character).
This means that when you type (the invalid HTML of) "start of tag" (<) the browser corrects it to "less than sign" (<) but when you type "start of entity" (&), which is allowed, no error correction takes place.
You need to write what you mean. If you want to include some HTML as data then you must convert any character with special meaning to its respective character reference.
If the data is:
<div
Then the HTML must be:
<textarea><div</textarea>
You can use the standard functions for converting this (e.g. PHP's htmlspecialchars or Perl's HTML::Entities module).
NB 1: If you were using XHTML[2] (and really using it, it doesn't count if you serve it as text/html) then you could use an explicit CDATA block:
<textarea><![CDATA[<div]]></textarea>
NB 2: Or if browsers implemented HTML 4 correctly
Ok , but the question is . why it decodes them anyway ? assuming i've added & , save the textarea , ti will be saved < , but displayed as < , saving it again will convert it back to < (but it will remain < in the database) , saving again will save it a < in the database , why the textarea decodes it ?
The server sends (to the browser) data encoded as HTML.
The browser sends (to the server) data encoded as application/x-www-form-urlencoded (or multipart/form-data).
Since the browser is not sending the data as HTML, the characters are not represented as HTML entities.
If you take the data received from the client and then put it into an HTML document, then you must encode it as HTML first.
In PHP, this can be done using htmlentities(). Example below.
<?php
$content = "This string contains the TM symbol: ™";
print "<textarea>". htmlentities($content) ."</textarea>";
?>
Without htmlentities(), the textarea would interpret and display the TM symbol (™) instead of "™".
http://php.net/manual/en/function.htmlentities.php
You have to be sure that this is rendered to the browser:
<textarea name="somename"><div</textarea>
Essentially, this means that the & in < has to be html encoded to &. How to do it will depend on the technologies you're using.
UPDATE: Think about it like this. If you want to display <div> inside a textarea, you'll have to encode <> because otherwise, <div> would be a normal HTML element to the browser:
<textarea name="somename"><div></textarea>
Having said this, if you want to display <div> inside a textarea, you'll have to encode & again, because the browser decodes HTML entities when rendering HTML. It has nothing to do with your database.
You can serve your DB-content from a separate page and then place it in the textarea using a Javascript (jQuery) Ajax-call:
request = $.ajax
({
type: "GET",
url: "url-with-the-troubled-content.php",
success: function(data)
{
document.getElementById('id-of-text-area').value = data;
}
});
Explained at
http://www.endtask.net/how-to-prevent-a-textarea-element-from-decoding-html-entities/
I had the same problem and I just made two replacements on the text to show from the database before letting it into the text area:
myString = Replace(myString, "&", "&")
myString = Replace(myString, "<", "<")
Replace n:o 1 to trick the textarea to show the codes.
replace n:o 2: Without this replacement you can not show the word "" inside the textarea (it would end the textarea tag).
(Asp / vbscript code above, translate to a replace method of your language choice)
I found an alternative solution for reading and working with in-browser, simply read the element's text() using jQuery, it returns the characters as display characters and allows me to write from a textarea to a div's innerHTML using the property via html()...
With only JS and HTML...
...to answer the actual question, with a bare-minimal example:
<textarea id=myta></textarea>
<script id=mytext type=text/plain>
™
</script>
<script> myta.value = mytext.innerText; </script>
Explanation:
Script tags do not render html nor entities. By storing text in a script tag, it will remain unadultered-- problem is it will try to execute as JavaScript. So we use an empty textarea and store the text in a script tag (here, the first one).
To prevent that, we change the mime-type to text/plain instead of it's default, which is text/javascript. This will prevent it from running.
Then to populate the textarea, we copy the script tag's content to it (here done in the second script tag).
The only caveats I have found with this are you have to use JavaScript and you cannot include script tags directly in it.
Say I have a form whose action target expects a value with spaces in it. If I were typing the request out manually as a URL, I'd use %20 to escape the spaces. If I use a hidden input for this parameter instead, should the value contain the spaces themselves, or the URL quoted %20 sequences?
Spaces! Let the browser HTML-escape the values for you on form submission.
When should I HTML-escape data in my code and when should I URL-escape? I am confused about which one when to use...
For example, given a element which asks for an URL:
<input type="text" value="DATA" name="URL">
Should I HTML-Escape DATA here or URL-escape it here?
And what about an element:
NAME
Should URL be URL-escaped or HTML-escaped? What about NAME?
Thanks, Boda Cydo.
URL encoding ensures that special characters such as ? and & don't cause the URL to be misinterpreted on the receiving end. In practice, this means you'll need to URL encode any dynamic query string values that have a chance of containing such characters.
HTML encoding ensures that special characters such as > and " don't cause the browser the misinterpret the markup. Therefore you need to HTML encode any values outputted into the markup that might contain such characters.
So in your example:
DATA needs to be HTML encoded.
Any dynamic segments of URL will need to be URL encoded, then the whole string will need to be HTML encoded.
Name needs to be HTML encoded.
HTML Escape when you're writing anything to a HTML document.
URL Escape when you're constructing a URL to call in-code, or for a browser to call (i.e. in the href tag).
In your examples you'll want to 'Attribute' escape the attributes. (I can't remember the exact function name, but it's in HttpUtility).
In the examples you show, it should be first URL-escaped, then HTML-escaped:
<a href="http://www.example.com?arg1=this%2C+that&arg2=blah">
I have to submit a HTML form to a 3rd party website and one of the hidden fields is an XML string. The XML needs escaping before it is sent to the 3rd party.
However when I add the plain XML to the form field it semi-escapes it for me. So then when I use HTMLEncode myself part of the XML is double-escaped. How do I prevent the automatic escaping that appears to becoming from .NET.
Or even better how else can send the escaped XML via the hidden field.
XML
<systemCode>APP</systemCode>
Basic assigning to hidden input field
<systemCode>APP</systemCode>
When I HTML Encode it as well
<systemCode>APP</systemCode>
I can see what's happening - but I don't know how to prevent it?
Don't use HTMLEncode as well ! Use it alone !
Something like:
'Setting value:
hdnField.Value = Server.HtmlEncode("<systemCode>APP</systemCode>")
'Outputs: <systemCode>APP</systemCode>
'Retrieving encoded value:
Dim escaped as string = Request.Form("hdnField")
'Retrieves: <systemCode>APP</systemCode>
'Retrieving decoded value:
Dim myValue As String = Server.HtmlDecode(Request.Form("hdnField"))
'Retrieves: "<systemCode>APP</systemCode>"
In the end I used a literal and then HTMLEncoding the XML string before assigned a HTML form variable to the literal text field. A little bit like below:
portalReq.Text = "<input type=""hidden"" name=""portalReq"" value='" & HTMLENCODE(RequestXML) & "' />"
Not elegant but it's circumventing the problem.
You don't need to worry about the HTML output. Only worry about what data is submitted in the form. It doesn't matter whether the HTML is fully escaped or partially escaped - the same data gets submitted either way.
Both of these fields:
<input name="xml" value="<systemCode>APP</systemCode>" />
<input name="xml" value="<systemCode>APP</systemCode>" />
Get submitted as:
xml=%3CsystemCode%3EAPP%3C%2FsystemCode%3E
This is language agnostic - it is browser behavior. When the browser parses the HTML, it will actually normalize both fields to have the same html. If you view source of the page, you will see that the source HTML differs between the inputs, but if you read the form.innerHTML value, you'll see that the parsed HTML is identical.
Demo:
http://jsfiddle.net/gilly3/Xdj5E/