Ruby-on-rails – Cannot skip validation in Rails 3

modelruby-on-railsruby-on-rails-3runtime-errorvalidation

I'm working on a project in Rails 3 where I need to create an empty record, save it to the database without validation (because it's empty), and then allow the users to edit this record in order to complete it, and validate from then on out.

Now I've run into a pretty basic problem: I can't seem to save a model without validating it under any circumstances.

I've tried the following in the console:

model = Model.new
model.save(false) # Returns RuntimeError: Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id
model.save( :validate => false ) # Returns same error as above

model = Model.create
model.save(false) # Same runtime error
model.save( :validate => false ) # Same runtime error

I then tried changing all the validations in the model to :on => :update. Same error messages on any attempt to save.

So what am I missing here? How can I create an empty record and then let validation occur as the user edits it?

Thanks!

Best Answer

It is a bad practice to have invalid models saved by normal use cases. Use conditional validations instead:

validates_presence_of :title, :unless => :in_first_stage?

or if you have many:

with_options :unless => :in_first_stage? do
  validates_presence_of :title
  validates_presence_of :author
end

This way nothing stands in way to have nightly integrity tests, which checks all records for validity.

A valid use case for saving without validations would be for testing edge cases, e.g. to test that a database constraint is enforced.

Related Solutions

Ruby-on-rails – Understanding the Rails Authenticity Token

What happens

When the user views a form to create, update, or destroy a resource, the Rails app creates a random authenticity_token, stores this token in the session, and places it in a hidden field in the form. When the user submits the form, Rails looks for the authenticity_token, compares it to the one stored in the session, and if they match the request is allowed to continue.

Why it happens

Since the authenticity token is stored in the session, the client cannot know its value. This prevents people from submitting forms to a Rails app without viewing the form within that app itself. Imagine that you are using service A, you logged into the service and everything is ok. Now imagine that you went to use service B, and you saw a picture you like, and pressed on the picture to view a larger size of it. Now, if some evil code was there at service B, it might send a request to service A (which you are logged into), and ask to delete your account, by sending a request to http://serviceA.com/close_account. This is what is known as CSRF (Cross Site Request Forgery).

If service A is using authenticity tokens, this attack vector is no longer applicable, since the request from service B would not contain the correct authenticity token, and will not be allowed to continue.

API docs describes details about meta tag:

CSRF protection is turned on with the protect_from_forgery method, which checks the token and resets the session if it doesn't match what was expected. A call to this method is generated for new Rails applications by default. The token parameter is named authenticity_token by default. The name and value of this token must be added to every layout that renders forms by including csrf_meta_tags in the HTML head.

Notes

Keep in mind, Rails only verifies not idempotent methods (POST, PUT/PATCH and DELETE). GET request are not checked for authenticity token. Why? because the HTTP specification states that GET requests is idempotent and should not create, alter, or destroy resources at the server, and the request should be idempotent (if you run the same command multiple times, you should get the same result every time).

Also the real implementation is a bit more complicated as defined in the beginning, ensuring better security. Rails does not issue the same stored token with every form. Neither does it generate and store a different token every time. It generates and stores a cryptographic hash in a session and issues new cryptographic tokens, which can be matched against the stored one, every time a page is rendered. See request_forgery_protection.rb.

Lessons

Use authenticity_token to protect your not idempotent methods (POST, PUT/PATCH, and DELETE). Also make sure not to allow any GET requests that could potentially modify resources on the server.

EDIT: Check the comment by @erturne regarding GET requests being idempotent. He explains it in a better way than I have done here.

Ruby-on-rails – calling custom validation methods in Rails

Your validations are executed when you use the validate method. However rails doesn't relies on the returned value.

It relies on if there are validations errors or not. So you should add errors when your model doesn't validates.

def something
    errors.add(:field, 'error message')
end

Or, if the error is not related to a field :

def something
    errors.add(:base, 'error message')
end

Then your model won't be saved because there are errors.

Best Answer

Related Solutions

Ruby-on-rails – Understanding the Rails Authenticity Token

Ruby-on-rails – calling custom validation methods in Rails

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