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validations.rb

Validations in Mongo 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.