Why are 'session' and 'params' available as local variables in the view but not 'errors'?

Question

I can write:

<%= debug(params) %>
<%= debug(session) %>

but not:

<%= debug(errors) %>

Why is the errors variable not available locally in the view?

Answer 1

Assuming errors refers to validation errors, params and session apply to your entire request and are therefore made available to your controller and views. errors apply to a specific model that you have instantiated (e.g. a person who is missing a name or a post which is missing a title) so there is no request-wide list of errors.