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    assignment.rb associations.rb basics.rb callbacks.rb composite.rb conversions.rb database.rb index.rb modifiers.rb queries.rb spec.rb validations.rb

  • validations.rb

  • ¶

    Validations in [Mongo Model][mongodb_model].

    There are following validation helpers available:

    validates_format_of
validates_length_of
validates_numericality_of
validates_acceptance_of
validates_confirmation_of
validates_presence_of
validates_true_for
validates_exclusion_of
validates_inclusion_of

    In this example we’ll create simple models for Blog application and use validations to ensure it’s correctness.

    require 'mongo/model'
  • ¶

    Connecting to test database and cleaning it before starting.

    Mongo::Model.default_database_name = :default_test
Mongo::Model.default_database.clear
  • ¶

    Basics

    Defining Post and requiring presence of text using validation helpers.

    class Post
  inherit Mongo::Model
  collection :posts

  attr_accessor :text
  • ¶

    Requiring presence of text.

      validates_presence_of :text
end
  • ¶

    Creating post, it can’t be saved because its text is empty and it’s invalid.

    post = Post.new
p post.valid?                                     # => false
p post.errors.size                                # => 1
p post.errors                                     # => {text: ["can't be empty"]}
p post.save                                       # => false
  • ¶

    Let’s add text to it so it will be valid and we can save it.

    post.text = 'Norad II crashed!'
p post.valid?                                     # => true
p post.save                                       # => true
  • ¶

    Usually when model is invalid it can’t be saved, but if You need You can skip validation and save invalid model.

    post = Post.new
p post.valid?                                     # => false
p post.save(validate: false)                      # => true
  • ¶

    Custom validations

  • ¶

    In previous sample ve used validates_presence_of helper to require presence of post text, let’s do the same by hand.

    Removing and creating new Post class.

    Object.send :remove_const, :Post

class Post
  inherit Mongo::Model
  collection :posts

  attr_accessor :text

  protected
  • ¶

    Creating method that valdiates text is not empty.

        def validate_text
      errors.add :text, "can't be empty" unless text and !text.empty?
    end
  • ¶

    Adding this method to validations (You can also use block instead of method).

        validate :validate_text
end
  • ¶

    Creating and saving new post.

    post = Post.new
p post.valid?                                     # => false
p post.errors                                     # => {text: ["can't be empty"]}
p post.save                                       # => false
  • ¶

    Let’s text it so it will be valid and we can save it.

    post.text = 'Norad II crashed!'
p post.valid?                                     # => true
p post.save                                       # => true
  • ¶

    Embedded Models

    MongoDB encourage to use Embedded Models a lot, so it’s important to provide validations for it.

  • ¶

    Adding comments to Post.

    class Post
  def comments; @comments ||= [] end
end
  • ¶

    Defining Comment.

    class Comment
  inherit Mongo::Model

  attr_accessor :text
  • ¶

    Validating presence of text in comment.

      validates_presence_of :text
end
  • ¶

    Creating post, there’s text and it’s valid.

    post = Post.new text: 'Norad II crashed!'
post.valid?                                       # => true
  • ¶

    Creating invalid comment with empty text.

    comment = Comment.new
p comment.valid?                                  # => false
  • ¶

    Validation of Parent model also does validation on all it’s childs, so adding invalid comment to valid post will make post also invalid.

    post.comments << comment
p post.valid?                                     # => false
p post.save                                       # => false
  • ¶

    In order to save post we need to make the comment valid.

    comment.text = "Where?"
p comment.valid?                                  # => true
p post.valid?                                     # => true
p post.save                                       # => true
  • ¶

    In this example we examined validation helpers, custom validation and validations for embedded models.