validation help please

rubyonrails-talk
1

Hi,

Can anyone take a look at this.... i've been banging my head on the wall for several days trying to figure this out. I can't figure out why the validation is bypassed. The only clue I have is it seems its not evaluating :question_type == "standard" to true.

Model: validates :question_type, :presence => true     if :question_type == "standard"       validates :question, :presence => true     ...

Controller: def create     @question = Question.new(params[:question])   if @question.save           if params[:question_type] == "standard"             flash[:success] = "Question created!"             redirect_to @question           else             .....

new.html.erb: <%= f.submit 'Save', question_type: "standard" ...

2

Is that code just inline in the model? If so then it is only executed once, when the code is loaded, so the if statement is not tested for each object being validated. Have a look at the Rails Guide on ActiveRecord Validations and Callbacks to see ways that you can accomplish what you want.

Colin

3

Hi Dave,

I believe you should do something along the lines of

Model:

  validates_each :question do |record, attr, value|     record.errors.add attr, 'The question is not present!?' if value.blank? and record.question_type=="standard"   end

plz correct me if I'm wrong, Colin :slight_smile:

cheers, Walther

4

Hi Dave,

I believe you should do something along the lines of

Model:

        validates_each :question do |record, attr, value|                 record.errors.add attr, 'The question is not present!?' if value.blank? and record.question_type=="standard"         end

plz correct me if I'm wrong, Colin :slight_smile:

It might be easier to use :if

Colin

5

This code is evaluated when the model is loaded. It compares the symbol :question_type to the string ‘standard’ (which are of course never equal) and so doesn’t add the validation.

You want the choice of whether to apply the validation or not to be taken when the model is about to be validated. The standard way of doing that is with the :if option

validates :question_type, :presence => true validates :question, :presence => true, :if => :standard_question?

will call the standard_question? method and only enforce the presence validation on question if the method returns true. There is also a lambda form

validates :question, :presence => true, :if => lambda {|record| record.question_type == ‘standard’}

Fred

6

Ok,

Thank you. I read Rails Guide on ActiveRecord Validations and Callbacks, specifically Conditional Validation.

So, validates :question, :presence => true, :if => "question_type.blank?" placed inline in model should be the simplest way to do this. It does not work however. My lack of understanding seems to be related to how I specify question_type in the condition?

As you can see i'm still on the bottom of the steep part of the learning curve.'

Thanks for the help

7

Frederick Cheung wrote in post #1099720:

8

Lambda method works, although I don't understand it :slight_smile:

Thanks!!

Dave

9

Yes - it’s up to you to write a standard_question? method. The lambda saves you having to have the condition in a separate method but can make your validation look more cluttered (especially for more complicated conditions).

Fred

10

Thanks again,

Is there a way to add a message if validation fails using lambda method (I am using Lambda method until I can figure out why validates :question, :presence => true, :if =>:standard_question? generates undefined method `standard_question?' for #<Question:0x007f947ddb2e00>)

11

Dave, you have to add an instance method “standard_question?” to your model

def standard_question?

end

from the url below you can see that you can pass a :message param to customize the error message

http://guides.rubyonrails.org/active_record_validations_callbacks.html#message

12

You want the choice of whether to apply the validation or not to be taken when the model is about to be validated. http://www.hqew.net