The other new method is any?, which (together with empty?) is one of a pair of complementary methods:

  We see here that the empty? method, which we first saw in Section 4.2.3 in the context of strings, also works on Rails error objects, returning true for an empty object and false otherwise. The any? method is just the opposite of empty?, returning true if there are any elements present and false otherwise. (By the way, all of these methods—count, empty?, and any?—work on Ruby arrays as well. We’ll put this fact to good use starting in Section 10.2.)

The other new idea is the pluralize text helper. It isn’t available in the console by default, but we can include it explicitly through the ActionView::Helpers:: TextHelper module:10

  We see here that pluralize takes an integer argument and then returns the number with a properly pluralized version of its second argument. Underlying this method is a powerful inflector that knows how to pluralize a large number of words, including many with irregular plurals:

 As a result of its use of pluralize, the code

returns "0 errors", "1 error", "2 errors", and so on, depending on how many errors there are, thereby avoiding ungrammatical phrases such as "1 errors" (a distressingly common mistake on teh interwebs). 

             Note that Listing 7.23 includes the CSS id error_explanation for use in styling the error messages. (Recall from Section 5.1.2 that CSS uses the pound sign # to style ids.) In addition, on error pages Rails automatically wraps the fields with errors in divs with the CSS class field_with_errors. These labels then allow us to style the error messages with the SCSS shown in Listing 7.24, which makes use of Sass’s @extend function to include the functionality of two Bootstrap classes control-group and error. As a result, on failed submission the error messages appear surrounded by red, as seen in Figure 7.17. Because the messages are generated by the model validations, they will automatically change if you ever change your mind about, say, the format of email addresses, or the minimum length of passwords.