Model Error Messages

A simple Rails helper which displays a HTML div with the validation errors attached to a model.

Install

Model Error Messages's installation is pretty standard, add the following line to your Gemfile, then run bundle install:

gem 'model_error_messages'

What this gem does / How to use

This gem allows you to use a helper called model_error_messages.
By default, the wrapper div has the Bootstrap-friendly classes alert alert-danger.
If you have a typical form, you would want to display model_error_messages(@model) next to it, which will render something like:

<div class="alert alert-danger article-error-messages">
  <ul>
    <li>Title can't be blank</li>
    <li>You must select an author</li>
  </ul>
</div>

... or if there is only one error:

<div class="alert alert-danger article-error-messages">
  <p>Title can't be blank</p>
</div>

Example of integration:

<%= model_error_messages(@article) %>

<%= form_for @article do |f| %>
  <!-- ... form fields ... -->
<% end %>

What this gem doesn't do

Include any other dependencies
Influence the generation of errors
Inject or execute any code in your controllers and models
Do anything with the flash messages
Anything not listed in "What this gem does"

Optional configuration

You can change the default behavior of model_error_messages by:

Setting an initializer

Create a file config/initializers/model_error_messages.rb and replace one of the defaults:

ModelErrorMessages.configure do |config|
  # Multiple errors will rendered in a several <li> in a <ul>, while one error will be rendered in a <p>
  config.single_error_in_paragraph = true

  # The following classes will be added in the main wrapper div.
  config.classes = lambda do |model|
    [
      'alert',
      'alert-danger',
      model.class.model_name.param_key + '-error-messages'
    ].join(' ')
  end

  # Note: you can pass a simple string to `config.classes`, example:
  # config.classes = 'alert alert-danger'

  # HTML that will be added before the list of errors.
  config.prepend_html = String.new

  # HTML that will be added after the list of errors.
  config.append_html = String.new
end

Passing options when calling `model_error_messages`

Examples:

<%= model_error_messages(@article, single_error_in_paragraph: false) %>

Contributing

Don't hesitate to send a pull request!

Testing

$ bundle install
$ bundle exec rspec spec/