Validation of other model fields


#1

I’ve got in my Form not only fileds from my model but also fields from
ither models. How can I validate them like other fields.

Example names od input tag fields

Name1 <%= text_field 'model1', 'name1' , :size => 40 %>

Name2 <%= text_field 'model1', 'name2' , :size => 40 %>

and from different model:

Name3 <%= text_field 'model2', 'name3' , :size => 40 %>

How can I validate presence_of field name3 from model2 model??


#2

Daniello wrote:

I’ve got in my Form not only fileds from my model but also fields from
ither models. How can I validate them like other fields.

Example names od input tag fields

Name1 <%= text_field 'model1', 'name1' , :size => 40 %>

Name2 <%= text_field 'model1', 'name2' , :size => 40 %>

and from different model:

Name3 <%= text_field 'model2', 'name3' , :size => 40 %>

How can I validate presence_of field name3 from model2 model??

I’m not sure I understand your question.

Would your controller not say something like

model1.update_attributes(params[“model1”])
model2.update_attributes(params[“model2”])

Then if you call

model1.save

it will not save if validation of model1 fails.

Likewise, model2.save will not save if model2 validation fails.

To save only if both validations pass you could call in your controller:

model1_valid = model1.valid?
model2_valid = model2.valid?

if (model1_valid && model2_valid)
model1.save_with_validation(false) # already validated
model2.save_with_validation(false) # already validated
else
# How do you handle failed validations?
end

But if your logic is that for this particular form, model2 should only
be saved if user has entered a value for a certain field of model1, then
you can perform that test in the controller:

if params[:model1][:certain_field].blank?
# handle error
end

Stephan


#3

The update_attributes method saves as well as updating the attribute.

b


#4

Daniello,

If there is a model association between the two models you can use the
following (copy/pasted from api.rubyonrails.org):

validates_associated(*attr_names)

Validates whether the associated object or objects are all valid
themselves. Works with any kind of association.

class Book < ActiveRecord::Base
has_many :pages
belongs_to :library

validates_associated :pages, :library

end

Warning: If, after the above definition, you then wrote:

class Page < ActiveRecord::Base
belongs_to :book

validates_associated :book

end

…this would specify a circular dependency and cause infinite
recursion.

NOTE: This validation will not fail if the association hasn’t been
assigned. If you want to ensure that the association is both present
and guaranteed to be valid, you also need to use
validates_presence_of.

Configuration options:

* on Specifies when this validation is active (default is :save,

other options :create, :update)
* if - Specifies a method, proc or string to call to determine if
the validation should

occur (e.g. :if => :allow_validation, or :if => Proc.new { |user|
user.signup_step > 2 }). The method, proc or string should return or
evaluate to a true or false value.

Regards,
Bas van Westing


#5

On 1-May-07, at 3:51 PM, Ben M. wrote:

Name3

Stephan
Daniello, hopefully the following will help move you forward. It will
leave you with an @errors for both models in your view that you can
iterate over

When managing validations for multiple models in one action I
typically use something like the following:

 @model1 = Model1.new(params[:model1])
 @model2 = Model2.new(params[:model2])

 respond_to do |format|
   if @ model1.valid? && @ model2.valid?
     #TODO: transaction here would help out
     @ model1.save(false)
     @ model1.save(false)
     flash[:notice] = 'Model1 and Model2 were successfully created.'
     format.html { render :partial => "my_partial" }
   else
     flash[:notice] = 'There were errors validating model1, model2'
     #merge_errors (below), merges the errors of 2 models into

one errors list
format.html { @errors = merge_errors(@model1, @model2);
render :partial => “/error_messages”, :errors => @errors, :status =>
500 }
end
end

#merges errors from 2 instances into 1 error object
def merge_errors(model1, model2)
if model1.errors.size > 0 && model2.errors.size > 0
model1.errors.instance_eval { @errors.merge
model2.errors.instance_values[‘errors’] }
elsif model1.errors.size > 0
model1.errors
elsif model2.errors.size > 0
model2.errors
else
model1.errors
end
end

Cheers,
Jodi
General Partner
The nNovation Group inc.
www.nnovation.ca/blog


#6

On 2-May-07, at 10:55 AM, Bas van Westing wrote:

belongs_to :book

validates_presence_of.
evaluate to a true or false value.

Regards,
Bas van Westing

now how did I miss that ?!

This is clearly a better route to go - for you and me, Daniello.

thanx Bas

Jodi