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Pavel Gabriel

2012-Jun-21 10:56 UTC

custom validations only if all attributes are valid

Hi!

I found that it''s a popular use case for AR/AM validations:

class User < AR::Base
  validates_numericality_of :age

  #custom validation
  validate :user_older_16

  def user_older_16
    errors.add(:age, "should be older 16") if age <= 16
  end
end

When you will try to validate as the following:
  
  user =  User.new(age: ''bla'')
  user.valid?

you will get: ArgumentError: comparison of String with 16 failed.

Folks write a lot of code to check attribute values in their custom 
validations, but it''s not a DRY way because attributes already
validated by
AM.

Is it a good idea to run validation methods only if errors.count == 0?

Or maybe we can add something like "validate_further :user_older_16"
that
will run only if attributes are valid?

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Steve Klabnik

2012-Jun-21 12:51 UTC

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Re: custom validations only if all attributes are valid

I think I''d be much more annoyed by this kind of behavior. "Okay,
these two things are wrong. Let''s fix them. Wait, now it''s
_still_
wrong, with something totally unrelated?"

You could fix this case almost trivially by ''if age.to_i <
16'', right?
I mean, I know you''re talking about a more general case, but...

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Carlos Antonio da Silva

2012-Jun-21 13:07 UTC

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Re: custom validations only if all attributes are valid

I agree with Steve, when we call valid?, we expect all validations to run. If
you want to skip some validation in case errors already exist in the object for
any particular reason, you can always to that as you said: `if errors.empty?`.
This will give you the behavior you expect, although I''d recommend
avoiding this and running all validations.

-- 
At.
Carlos Antonio


On Thursday, June 21, 2012 at 9:51 AM, Steve Klabnik wrote:
> I think I''d be much more annoyed by this kind of behavior.
"Okay,
> these two things are wrong. Let''s fix them. Wait, now
it''s _still_
> wrong, with something totally unrelated?"
> 
> You could fix this case almost trivially by ''if age.to_i <
16'', right?
> I mean, I know you''re talking about a more general case, but...
> 
> -- 
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> 
> 

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Ken Collins

2012-Jun-21 13:10 UTC

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Re: custom validations only if all attributes are valid

Agreed, and by "running all validations" you can have a certain
validator that acts as a state machine on a set of validations that gives more
meaningful errors as the state moves forward. I think most of us have done that
in the past to get the behavior you are looking for. Changing core behavior for
that case does not make sense.

 - Ken

On Jun 21, 2012, at 9:07 AM, Carlos Antonio da Silva wrote:
> I agree with Steve, when we call valid?, we expect all validations to run.
If you want to skip some validation in case errors already exist in the object
for any particular reason, you can always to that as you said: `if
errors.empty?`. This will give you the behavior you expect, although
I''d recommend avoiding this and running all validations.
> 
> -- 
> At.
> Carlos Antonio
> 
> On Thursday, June 21, 2012 at 9:51 AM, Steve Klabnik wrote:
> 
>> I think I''d be much more annoyed by this kind of behavior.
"Okay,
>> these two things are wrong. Let''s fix them. Wait, now
it''s _still_
>> wrong, with something totally unrelated?"
>> 
>> You could fix this case almost trivially by ''if age.to_i <
16'', right?
>> I mean, I know you''re talking about a more general case,
but...
>> 
>> --
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Groups "Ruby on Rails: Core" group.
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> 
> 
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Anthony Richardson

2012-Jun-22 00:23 UTC

head link

Re: custom validations only if all attributes are valid

I can see some advantge of declaring a validation dependency. Checking
if an age is less than 16 makes no sense if the age has failed a
validation on being a number already.

maybe something like:

class User < AR::Base
   validates_numericality_of :age

   #custom validation
   validate :user_older_16, :depends => :age

   def user_older_16
     errors.add(:age, "should be older 16") if age <= 16
   end
 end

Where :user_older_16 would only run if age has no errors. In the
context shown above this is a sensible dependency, but used
incorrectly the concerns expressed by others would be valid.

Another suggestion:

class User < AR::Base

   validates_with_dependency do
     validates_numericality_of :age
     validate :user_older_16
   end

   def user_older_16
     errors.add(:age, "should be older 16") if age <= 16
   end
 end

In the above the validations in the validate_with_dependency block
would execute in order, exiting the sequence if any fail.

I think the suggestion to have dependent validaiton is a good one as
it allows for structuring simiple validations where you know a
validation cannot possibly pass if an earlier one has failed.

Cheers,

Anthony Richardson.

On Thu, Jun 21, 2012 at 8:26 PM, Pavel Gabriel <alovak@gmail.com>
wrote:> Hi!
>
> I found that it''s a popular use case for AR/AM validations:
>
> class User < AR::Base
>   validates_numericality_of :age
>
>   #custom validation
>   validate :user_older_16
>
>   def user_older_16
>     errors.add(:age, "should be older 16") if age <= 16
>   end
> end
>
> When you will try to validate as the following:
>
>   user =  User.new(age: ''bla'')
>   user.valid?
>
> you will get: ArgumentError: comparison of String with 16 failed.
>
> Folks write a lot of code to check attribute values in their custom
> validations, but it''s not a DRY way because attributes already
validated by
> AM.
>
> Is it a good idea to run validation methods only if errors.count == 0?
>
> Or maybe we can add something like "validate_further
:user_older_16" that
> will run only if attributes are valid?
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Core" group.
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Rodrigo Rosenfeld Rosas

2012-Jun-22 00:32 UTC

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Re: custom validations only if all attributes are valid

Yeah, I couldn''t understand what Ken meant by his
"state-machine" approach.

I can''t think of a dry way of currently doing that.

I''m just not much concerned about this as I don''t use AR and
Sequel''s
way of doing validation is by defining a "validate" method, so
I''d put
my logic there, but anyway...

Em 21-06-2012 21:23, Anthony Richardson escreveu:> I can see some advantge of declaring a validation dependency. Checking
> if an age is less than 16 makes no sense if the age has failed a
> validation on being a number already.
>
> maybe something like:
>
> class User<  AR::Base
>     validates_numericality_of :age
>
>     #custom validation
>     validate :user_older_16, :depends =>  :age
>
>     def user_older_16
>       errors.add(:age, "should be older 16") if age<= 16
>     end
>   end
>
> Where :user_older_16 would only run if age has no errors. In the
> context shown above this is a sensible dependency, but used
> incorrectly the concerns expressed by others would be valid.
>
> Another suggestion:
>
> class User<  AR::Base
>
>     validates_with_dependency do
>       validates_numericality_of :age
>       validate :user_older_16
>     end
>
>     def user_older_16
>       errors.add(:age, "should be older 16") if age<= 16
>     end
>   end
>
> In the above the validations in the validate_with_dependency block
> would execute in order, exiting the sequence if any fail.
>
> I think the suggestion to have dependent validaiton is a good one as
> it allows for structuring simiple validations where you know a
> validation cannot possibly pass if an earlier one has failed.
>
> Cheers,
>
> Anthony Richardson.
>
> On Thu, Jun 21, 2012 at 8:26 PM, Pavel Gabriel<alovak@gmail.com> 
wrote:
>> Hi!
>>
>> I found that it''s a popular use case for AR/AM validations:
>>
>> class User<  AR::Base
>>    validates_numericality_of :age
>>
>>    #custom validation
>>    validate :user_older_16
>>
>>    def user_older_16
>>      errors.add(:age, "should be older 16") if age<= 16
>>    end
>> end
>>
>> When you will try to validate as the following:
>>
>>    user =  User.new(age: ''bla'')
>>    user.valid?
>>
>> you will get: ArgumentError: comparison of String with 16 failed.
>>
>> Folks write a lot of code to check attribute values in their custom
>> validations, but it''s not a DRY way because attributes already
validated by
>> AM.
>>
>> Is it a good idea to run validation methods only if errors.count == 0?
>>
>> Or maybe we can add something like "validate_further
:user_older_16" that
>> will run only if attributes are valid?
>>
>> --
>> You received this message because you are subscribed to the Google
Groups
>> "Ruby on Rails: Core" group.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msg/rubyonrails-core/-/Ca3mpVVPWlgJ.
>> To post to this group, send email to rubyonrails-core@googlegroups.com.
>> To unsubscribe from this group, send email to
>> rubyonrails-core+unsubscribe@googlegroups.com.
>> For more options, visit this group at
>> http://groups.google.com/group/rubyonrails-core?hl=en.
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Ken Collins

2012-Jun-22 01:39 UTC

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Re: custom validations only if all attributes are valid

A poor choice of words maybe, I was trying to say that at some point in time, I
have had models that needed a hierarchy of potential errors and that some errors
are not appropriate to show at certain times. A object that goes thru states is
a good example.

 - Ken

On Jun 21, 2012, at 8:32 PM, Rodrigo Rosenfeld Rosas wrote:
> Yeah, I couldn''t understand what Ken meant by his
"state-machine" approach.
> 
> I can''t think of a dry way of currently doing that.
> 
> I''m just not much concerned about this as I don''t use AR
and Sequel''s way of doing validation is by defining a
"validate" method, so I''d put my logic there, but anyway...
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Pavel Gabriel

2012-Jun-25 10:11 UTC

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Re: custom validations only if all attributes are valid

Steve, It''s easy to reply to your post, because you have a code example
:)

In you case, you will have to duplicate all checks in your custom 
validations, that is not DRY approach.

You will duplicate .to_i in all methods that will depends on age as integer.

On Thursday, June 21, 2012 3:51:42 PM UTC+3, Steve Klabnik
wrote:>
> I think I''d be much more annoyed by this kind of behavior.
"Okay,
> these two things are wrong. Let''s fix them. Wait, now
it''s _still_
> wrong, with something totally unrelated?" 
>
> You could fix this case almost trivially by ''if age.to_i <
16'', right?
> I mean, I know you''re talking about a more general case, but... 
>
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Pavel Gabriel

2012-Jun-25 10:21 UTC

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Re: custom validations only if all attributes are valid

Carlos,

I agree with you. Technically I can check that errors are empty, but I have 
to do it in all my custom validations.

it will not look nice :(

What I offer is a two stage validation. When on the second stage you will 
be sure that all data in correct state and you can use it with confidence.

Anyway you will rely on one *valid?* method.

What I added into my project is:

https://gist.github.com/2987785

The reason I did it is a lot of exceptions we got when our clients
didn''t
provide all necessary data (or in correct format).
The obvious solution of course was to manually check all data in custom 
validations, but why I need to duplicate code if AR/AM already implemented 
it?

On Thursday, June 21, 2012 4:07:09 PM UTC+3, Carlos Antonio da Silva
wrote:>
> I agree with Steve, when we call valid?, we expect all validations to run. 
> If you want to skip some validation in case errors already exist in the 
> object for any particular reason, you can always to that as you said: `if 
> errors.empty?`. This will give you the behavior you expect, although
I''d
> recommend avoiding this and running all validations.
>
> -- 
> At.
> Carlos Antonio
>
> On Thursday, June 21, 2012 at 9:51 AM, Steve Klabnik wrote:
>
> I think I''d be much more annoyed by this kind of behavior.
"Okay,
> these two things are wrong. Let''s fix them. Wait, now
it''s _still_
> wrong, with something totally unrelated?"
>
> You could fix this case almost trivially by ''if age.to_i <
16'', right?
> I mean, I know you''re talking about a more general case, but...
>
> -- 
> You received this message because you are subscribed to the Google Groups 
> "Ruby on Rails: Core" group.
> To post to this group, send email to rubyonrails-core@googlegroups.com.
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> rubyonrails-core+unsubscribe@googlegroups.com.
> For more options, visit this group at 
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>
>  
>  
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Pavel Gabriel

2012-Jun-26 13:54 UTC

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Re: custom validations only if all attributes are valid

Anthony, good point!

validates_with_dependency is the a specific case of suggested 
''validate_further'' approach.

Two stage validation doesn''t require you to manage dependencies (order,
etc.) so no need to specify them.

You just rely on results from first stage.

One more example from real project:

order.rb

validates_presence_of :shop
validates_presence_of :line_items
validates_associated :billing_address

...
 
validate_further :on => :create do
  errors.add(:signature, :invalid) unless signature_verified?
end

method signature_verified? calculates signature with

   - shop.secret_key  - shop should present
   - amount, quantity, name for each line_item
   - attributes for billing/shipping, etc.

and compares it with received value from user

do I really have to check manually that everything valid before calculate 
signature?


On Friday, June 22, 2012 3:23:56 AM UTC+3, Richo99
wrote:>
> I can see some advantge of declaring a validation dependency. Checking 
> if an age is less than 16 makes no sense if the age has failed a 
> validation on being a number already. 
>
> maybe something like: 
>
> class User < AR::Base 
>    validates_numericality_of :age 
>
>    #custom validation 
>    validate :user_older_16, :depends => :age 
>
>    def user_older_16 
>      errors.add(:age, "should be older 16") if age <= 16 
>    end 
>  end 
>
> Where :user_older_16 would only run if age has no errors. In the 
> context shown above this is a sensible dependency, but used 
> incorrectly the concerns expressed by others would be valid. 
>
> Another suggestion: 
>
> class User < AR::Base 
>
>    validates_with_dependency do 
>      validates_numericality_of :age 
>      validate :user_older_16 
>    end 
>
>    def user_older_16 
>      errors.add(:age, "should be older 16") if age <= 16 
>    end 
>  end 
>
> In the above the validations in the validate_with_dependency block 
> would execute in order, exiting the sequence if any fail. 
>
> I think the suggestion to have dependent validaiton is a good one as 
> it allows for structuring simiple validations where you know a 
> validation cannot possibly pass if an earlier one has failed. 
>
> Cheers, 
>
> Anthony Richardson. 
>
> On Thu, Jun 21, 2012 at 8:26 PM, Pavel Gabriel <alovak@gmail.com>
wrote:
> > Hi! 
> > 
> > I found that it''s a popular use case for AR/AM validations: 
> > 
> > class User < AR::Base 
> >   validates_numericality_of :age 
> > 
> >   #custom validation 
> >   validate :user_older_16 
> > 
> >   def user_older_16 
> >     errors.add(:age, "should be older 16") if age <= 16 
> >   end 
> > end 
> > 
> > When you will try to validate as the following: 
> > 
> >   user =  User.new(age: ''bla'') 
> >   user.valid? 
> > 
> > you will get: ArgumentError: comparison of String with 16 failed. 
> > 
> > Folks write a lot of code to check attribute values in their custom 
> > validations, but it''s not a DRY way because attributes
already validated
> by 
> > AM. 
> > 
> > Is it a good idea to run validation methods only if errors.count == 0?
> > 
> > Or maybe we can add something like "validate_further
:user_older_16"
> that 
> > will run only if attributes are valid? 
> > 
> > -- 
> > You received this message because you are subscribed to the Google 
> Groups 
> > "Ruby on Rails: Core" group. 
> > To view this discussion on the web visit 
> > https://groups.google.com/d/msg/rubyonrails-core/-/Ca3mpVVPWlgJ. 
> > To post to this group, send email to
rubyonrails-core@googlegroups.com.
> > To unsubscribe from this group, send email to 
> > rubyonrails-core+unsubscribe@googlegroups.com. 
> > For more options, visit this group at 
> > http://groups.google.com/group/rubyonrails-core?hl=en. 
>
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Andrew White

2012-Jun-27 00:56 UTC

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Re: custom validations only if all attributes are valid

If you only want to run a validation on an attribute if it is valid at that
point in the validation process then here''s a trick:

module AttributeValidation
  extend ActiveSupport::Concern

  included do
    attribute_method_suffix ''_valid?'',
''_invalid?''
  end

  private

  def attribute_valid?(attr)
    !attribute_invalid?(attr)
  end

  def attribute_invalid?(attr)
    errors.include?(attr.to_sym)
  end
end

include this module in AR::Base or specific models - it''s up to you.
Once included you can then set up your validations like this:

class User < ActiveRecord::Base
  include AttributeValidation

  attr_accessible :name, :age

  validates :name, presence: true, length: { maximum: 100 }
  validates :age, presence: true, numericality: { only_integer: true }
  validate :over_minimum_age, if: :age_valid?

  def over_minimum_age
    errors.add(:age, :invalid) if age < 16
  end
end

this will only run the minimum age validation once it has passed the presence
and numericality checks. One advantage of doing this is you don''t need
guard checks when comparing the age (normally you''d get a
"NoMethodError: undefined method `<'' for nil:NilClass")


Andrew

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Pavel Gabriel

2012-Jun-28 10:40 UTC

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Re: custom validations only if all attributes are valid

Guys,

there are people who see a value in validation dependency and who
don''t.

I want to add this to Rails core and ready to make a pull request.
But I need some help about the name of the method (validate_after, 
validate_with_dependency, validate_further, etc.)   and usage of this 
approach.

I posted earlier what I use on my project. I think that the interface of 
this method should be the same with validate method (:on, :if/:unless).


On Thursday, June 21, 2012 1:56:39 PM UTC+3, Pavel Gabriel
wrote:>
> Hi!
>
> I found that it''s a popular use case for AR/AM validations:
>
> class User < AR::Base
>   validates_numericality_of :age
>
>   #custom validation
>   validate :user_older_16
>
>   def user_older_16
>     errors.add(:age, "should be older 16") if age <= 16
>   end
> end
>
> When you will try to validate as the following:
>   
>   user =  User.new(age: ''bla'')
>   user.valid?
>
> you will get: ArgumentError: comparison of String with 16 failed.
>
> Folks write a lot of code to check attribute values in their custom 
> validations, but it''s not a DRY way because attributes already
validated by
> AM.
>
> Is it a good idea to run validation methods only if errors.count == 0?
>
> Or maybe we can add something like "validate_further
:user_older_16" that
> will run only if attributes are valid?
>
>
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Rails core - Jun 2012 - custom validations only if all attributes are valid

custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid

Re: custom validations only if all attributes are valid