Handle MongoDB arrays in Rails Forms

An example post:

{
  title: 'Editing MongoDB Arrays in Rails'
  tags: ['ruby', 'rails', 'mongodb']
}

Create a model with two new methods like this:

class Post
  include Mongoid::Document

  field :title, type: String
  field :tags, type: Array, default: []

  def tags_list=(arg)
    self.tags = arg.split(',').map { |v| v.strip }
  end

  def tags_list
    self.tags.join(', ')
  end
end

The in your view form, use the following instead of the tags field

<%= f.text_field :tags_list %>

Any comma seperated values in the field, will be saved as individual items in an array.

Example:

post = Post.new
post.tags_list = 'tag1, tag2, tag3'
=> "tag1, tag2, tag3"

post.tags
=> ["Tag1", "Tag2", "Tag3"]

Originally blogged at (http://blog.codiez.co.za/2013/07/editing-mongodb-arrays-in-rails/)