How to use validates_uniqueness_of with ActiveModel?

Question

I'm using ActiveModel to make my tableless models feel like ActiveRecord models. I'm using a custom store and I need to be able to validate uniqueness of a record.

How can I implement the required uniqueness check using ActiveModel?

Roman · Answer 1 · 2012-09-18T04:30:33.247

1

I ended up doing something like this:

class Theme < Base

  include ActiveModel::Validations

  attr_accessor :id, :name
  validate      :uniqueness_of_theme_name, :on => :create

  def initialize(attrs = {})
    attrs.each do |name, value|
      send("#{name}=", value)
    end
  end

  def uniqueness_of_theme_name
    errors.add(:name, "name is already in use") unless Theme.find_by_name(name).nil?
  end

  def self.find_by_name(name)
    return store.find({ 'name' => "/^#{name}$/i" }).any?
  end

  def self.create(attributes = {})
    theme = Theme.new(attributes)
    theme.save

    return theme
  end

  def persisted?
    id && !id.nil?
  end

  def save()
    # only call validation during create context
    context = persisted? :update : :create
    false if invalid?(context)
    store.save(self)
    true
  end

  def self.create(attrs = {})
    theme = Theme.new(attrs)
    theme.save
    theme
  end

end

Maybe someone can tell me if this was the correct way to go about it

edited Sep 18 '12 at 04:30

answered Sep 18 '12 at 01:40

Roman

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I cant understand, where are you storing this themes, so it can be validated as unique, – Rodrigo Zurek Sep 18 '12 at 01:53
@RodrigoZurek, My store is actually mongodb. I've updated the code above. It's not complete but it should give you a better idea. – Roman Sep 18 '12 at 04:31
what includes of your **Base** class? – Anatoly Sep 18 '12 at 04:40
The base class includes some basic code that lets models interact with mongodb – Roman Sep 18 '12 at 05:00

score -1 · Answer 2 · answered Sep 18 '12 at 01:25

-1

Check this railscasts, it might help

http://railscasts.com/episodes/193-tableless-model

once you do your model, add the validations and then @model.valid?

answered Sep 18 '12 at 01:25

Rodrigo Zurek

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I know that tutorial is about table less models but it doesn't have any examples of uniqueness checks. – Roman Sep 18 '12 at 01:37

score -1 · Answer 3 · answered Sep 18 '12 at 04:39

-1

ActiveModel can be used with according to another railscasts, which is more suitable for that use-case.

class Theme

  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_accessor :id, :name

  validates :name, uniqueness: true, on: :create

  def initialize(attributes = {})
    attributes.each do |name, value|
      send("#{name}=", value)
    end
  end

  def persisted?
    false
  end
end

answered Sep 18 '12 at 04:39

Anatoly

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@mikhailob, based on what does the above code check the uniqueness of `:name`? I think validating uniqueness is a especial situation where it's correctness heavily relies on there being a data store and could not have been abstracted into the ActiveModel which doesn't require tables at all. – Roman Sep 18 '12 at 05:02
1

@Arman ActiveModel validation does happen once you call **save** (or explicit **valid?** method) on the Ruby object before any attempts to save data into MongoDB (or whatever you want). ActiveModel is an abstraction can help you to use plain object like ActiveRecord table-behind model. – Anatoly Sep 18 '12 at 05:35

How to use validates_uniqueness_of with ActiveModel?

3 Answers3