Rails - Jan 2013 - how to perform validation prior to creating a new association between records?

Hi,

I''m trying to figure out the correct "Rails" way to perform
validation
prior to creating a new assocation between my models. Here''s the
models:

class User < ActiveRecord::Base
  
  has_and_belongs_to_many :roles
  has_many :instructorships
  has_many :instructed_courses, :through => :instructorships, :source => 
:course

class Course < ActiveRecord::Base
  
  has_many :instructorships
  has_many :instructors, :through => :instructorships, :source => 
:instructor

class Instructorship < ActiveRecord::Base
  belongs_to :instructor, :class_name => ''User'',
:foreign_key => ''user_id''
  belongs_to :course

I''m trying to introduce a validation whereby only user objects with a
role
of ''instructor'' can be assigned as an instructor on a course. 

Firstly, where would this validation go? On the association model? And 
secondly, what is the right way to set this up?

thanks for your help,
Cathal.

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The validation would go in the Instructorship model.

You''ll need a custom method, like so:
http://edgeguides.rubyonrails.org/active_record_validations.html#custom-methods

-- 
Dheeraj Kumar


On Thursday 3 January 2013 at 8:43 PM, coriordan wrote:
> Hi,
> 
> I''m trying to figure out the correct "Rails" way to
perform validation prior to creating a new assocation between my models.
Here''s the models:
> 
> class User < ActiveRecord::Base
>   
>   has_and_belongs_to_many :roles
>   has_many :instructorships
>   has_many :instructed_courses, :through => :instructorships, :source
=> :course
> 
> class Course < ActiveRecord::Base
>   
>   has_many :instructorships
>   has_many :instructors, :through => :instructorships, :source =>
:instructor
> 
> class Instructorship < ActiveRecord::Base
>   belongs_to :instructor, :class_name => ''User'',
:foreign_key => ''user_id''
>   belongs_to :course
> 
> I''m trying to introduce a validation whereby only user objects
with a role of ''instructor'' can be assigned as an instructor
on a course.
> 
> Firstly, where would this validation go? On the association model? And
secondly, what is the right way to set this up?
> 
> thanks for your help,
> Cathal.
> -- 
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>  
>  
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Thanks Dheeraj :)



On Thursday, 3 January 2013 18:57:45 UTC, Dheeraj Kumar
wrote:
>
> The validation would go in the Instructorship model.
>
> You''ll need a custom method, like so: 
>
http://edgeguides.rubyonrails.org/active_record_validations.html#custom-methods
>
> -- 
> Dheeraj Kumar
>
> On Thursday 3 January 2013 at 8:43 PM, coriordan wrote:
>
> Hi,
>
> I''m trying to figure out the correct "Rails" way to
perform validation
> prior to creating a new assocation between my models. Here''s the
models:
>
> class User < ActiveRecord::Base
>   
>   has_and_belongs_to_many :roles
>   has_many :instructorships
>   has_many :instructed_courses, :through => :instructorships, :source
=>
> :course
>
> class Course < ActiveRecord::Base
>   
>   has_many :instructorships
>   has_many :instructors, :through => :instructorships, :source => 
> :instructor
>
> class Instructorship < ActiveRecord::Base
>   belongs_to :instructor, :class_name => ''User'',
:foreign_key => ''user_id''
>   belongs_to :course
>
> I''m trying to introduce a validation whereby only user objects
with a role
> of ''instructor'' can be assigned as an instructor on a
course.
>
> Firstly, where would this validation go? On the association model? And 
> secondly, what is the right way to set this up?
>
> thanks for your help,
> Cathal.
>
> -- 
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> "Ruby on Rails: Talk" group.
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> .
> To unsubscribe from this group, send email to 
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<javascript:>.
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> https://groups.google.com/d/msg/rubyonrails-talk/-/bUuvgClzISMJ.
> For more options, visit https://groups.google.com/groups/opt_out.
>  
>  
>  
>  
>  
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