An old plugin for handling blank values

This article is deprecated.I've marked this article as deprecated. It is either because the gem or plugin discussed in this article is no longer maintained, or I've changed my opinion on it. This article is here only as an historic reference.

no_value_helper plugin

It took some late night coding, but I finished another plugin. It's a little helper that goes by the name of no_value_helper. To install it, type: ./script/plugin install git://github.com/iain/no_value_helper.git. It's not that big, but fully tested, which may save you some time.

It changes:

<%= @user.name.blank? ? 'no value' : h(@user.name) %>

Into:

<%= show(@user.name, :h) %>

But wait! There is more! This method can accept blocks too and rescue you from those pesky nils! Keep on reading!

The problem I wanted to solve

This Ruby on Rails plugin tries to solve a common pattern when showing values from the database. If you want to show a nice message like 'no value' when an optional attribute has been left empty, you usually need to do the same thing over and over again:

<%= @user.name.blank? ? 'no value' : @user.name %>

It gets even worse when it's about an optional relation, with some extra methods:

<%= @user.daddy ? link_to(@user.daddy.name, @user.daddy) : 'no daddy' %>

The solution: no_value_helper

So this plugin tries to shorten this:

<%= show(@user.name) %>

Or the second example:

<%= show(:link_to, @user.daddy) { @user.daddy.name } %>

Don't worry, NoMethodErrors will be caught for you. That is why we use a block in this case.

For the exact usage, read the specs.

Configuration

To translate the message, you can simply add the "no_value" key (no scope) to your translation files.

nl-NL:
  no_value: geen waarde

By default the message is encapsulated by an em-tag with the class 'no_value'. To change this, set the class variable @@no_value_text with a lambda. This is done so I18n.translate will work. Make an initializer (in config/initializers/no_value_helper.rb), containing this:

module NoValueHelper
  @@no_value_text = lambda { "something more to your liking" }
end

You can also change how this plugin checks for empty values. By default this is done with the method blank? This means that empty strings are also treated as 'no value'. To change this, set the class variable @@no_value_check_method to a lambda that does what you want. Your initializer will look something like this:

module NoValueHelper
  @@no_value_check_method = lambda { |value| value.nil? }
end

Some more examples

Here are some more examples to inspire you:

<%= show(:l, :format => :long){@user.birthday} %>
<%= show(@user.savings, :number_to_currency) %>
<%= show(:simple_format){@user.contract.company.billing_address} %>
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