Suppose I have the following string
@x = "<a href='#'>Turn me into a link</a>"
In my view, I want a link to be displayed. That is, I don't want everything in @x to be unescaped and displayed as a string. What's the difference between using
<%= raw @x %>
<%= h @x %>
<%= @x.html_safe %>
?
This question is related to
ruby-on-rails
erb
Considering Rails 3:
html_safe actually "sets the string" as HTML Safe (it's a little more complicated than that, but it's basically it). This way, you can return HTML Safe strings from helpers or models at will.
h can only be used from within a controller or view, since it's from a helper. It will force the output to be escaped. It's not really deprecated, but you most likely won't use it anymore: the only usage is to "revert" an html_safe declaration, pretty unusual.
Prepending your expression with raw is actually equivalent to calling to_s chained with html_safe on it, but is declared on a helper, just like h, so it can only be used on controllers and views.
"SafeBuffers and Rails 3.0" is a nice explanation on how the SafeBuffers (the class that does the html_safe magic) work.
The difference is between Rails’ html_safe() and raw(). There is an excellent post by Yehuda Katz on this, and it really boils down to this:
def raw(stringish)
stringish.to_s.html_safe
end
Yes, raw() is a wrapper around html_safe() that forces the input to String and then calls html_safe() on it. It’s also the case that raw() is a helper in a module whereas html_safe() is a method on the String class which makes a new ActiveSupport::SafeBuffer instance — that has a @dirty flag in it.
Refer to "Rails’ html_safe vs. raw".
html_safe :
Marks a string as trusted safe. It will be inserted into HTML with no additional escaping performed.
"<a>Hello</a>".html_safe
#=> "<a>Hello</a>"
nil.html_safe
#=> NoMethodError: undefined method `html_safe' for nil:NilClass
raw :
raw is just a wrapper around html_safe. Use raw if there are chances that the string will be nil.
raw("<a>Hello</a>")
#=> "<a>Hello</a>"
raw(nil)
#=> ""
h alias for html_escape :
A utility method for escaping HTML tag characters. Use this method to escape any unsafe content.
In Rails 3 and above it is used by default so you don't need to use this method explicitly
I think it bears repeating: html_safe does not HTML-escape your string. In fact, it will prevent your string from being escaped.
<%= "<script>alert('Hello!')</script>" %>
will put:
<script>alert('Hello!')</script>
into your HTML source (yay, so safe!), while:
<%= "<script>alert('Hello!')</script>".html_safe %>
will pop up the alert dialog (are you sure that's what you want?). So you probably don't want to call html_safe on any user-entered strings.
In Simple Rails terms:
h remove html tags into number characters so that rendering won't break your html
html_safe sets a boolean in string so that the string is considered as html save
raw It converts to html_safe to string
The best safe way is: <%= sanitize @x %>
It will avoid XSS!
Source: Stackoverflow.com