Question

I’m upgrading an application from Rails 2 to Rails 3. Apparently, calling render() now returns ActionView::OutputBuffer and not String. I need to pass the results of render() to URI.escape(), and this fails with exception…

Here is my brief testing in the console

ob = ActionView::OutputBuffer.new("test test")
URI.escape(ob)
    `NoMethodError: undefined method 'each_byte' for nil:NilClass`. 
        from /opt/ruby19/lib/ruby/1.9.1/uri/common.rb:307:in `block in escape'
        from ..../ruby/1.9.1/gems/activesupport-3.2.1/lib/active_support/core_ext/string/output_safety.rb:160:in `gsub'
        from ..../ruby/1.9.1/gems/activesupport-3.2.1/lib/active_support/core_ext/string/output_safety.rb:160:in `gsub'
        from /opt/ruby19/lib/ruby/1.9.1/uri/common.rb:304:in `escape'
        from /opt/ruby19/lib/ruby/1.9.1/uri/common.rb:623:in `escape'

Moreover, calling to_s on OutputBuffer returns same OutputBuffer class, so I cannot even convert this buffer into a honest string?

ob.to_s.class 
    ActionView::OutputBuffer

Of course, calling URI.escape(“test test”) returns “test%20test” as expected, so this is not URI problem.

Environment:

• ruby 1.9.3p125 (2012-02-16 revision 34643) [i686-linux]
• Rails 3.2.1

My question is: Why does this happen and how can I work around this issue?

Update: Apparently, using '' + ob as a form of ob.to_s converts OutputBuffer to String, which effectively works around the problem… But my question ‘why does this happen‘ still remains, e.g. is this a bug, should I report it, or I’m doing something wrong?

Answer 1

This is a bug in Rails:

When calling gsub with a block on an ActiveSupport::SafeBuffer the global variables $1, $2, etc. for referencing submatches are not always properly set (anymore?) when the block is called.

This is why URI.escape (and any other function that uses gsub() will fail on ActiveSupprt::Safebuffer.

There are several discussions about this, apparently the safest route right now is to call to_str before passing SafeBuffer to anything that can call gsub, e.g. URI.encode, escape_javascript and similar functions.

My other quesion about to_s returning the same class – obviously safe buffer will return itself and not a bare String, this is by design. In order to get a true String, .to_str can be used.