Eddie Hillenbrand
2006-Feb-09 19:57 UTC
[Rails] accessing associated models in a validate method
Why can''t I access an associated model in a validate method? I have some code that looks like the following: Models: class Product < ActiveRecord::Base has_many: upcs end class Upc < ActiveRecord::Base belongs_to :product def validate errors.add_on_blank(''upc'') unless product.new_record? end end Controller: def create @product = Product.new(params[:product]) @upc = Upc.new(params[:upc]) @product.upcs << @upc unless @upc.upc.empty? if @product.save # ... end end When the create method gets called I get the NoMethodError "The error occured while evaluating nil.new_record?" Why is product nil? How can I access associated models in a validate method. Thanks.
Mark Reginald James
2006-Feb-10 10:38 UTC
[Rails] Re: accessing associated models in a validate method
Eddie Hillenbrand wrote:> Why can''t I access an associated model in a validate method? I have > some code that looks like the following: > > Models: > class Product < ActiveRecord::Base > has_many: upcs > end > > class Upc < ActiveRecord::Base > belongs_to :product > def validate > errors.add_on_blank(''upc'') unless product.new_record? > end > end > > Controller: > def create > @product = Product.new(params[:product]) > @upc = Upc.new(params[:upc]) > @product.upcs << @upc unless @upc.upc.empty? > > if @product.save > # ... > end > end > > When the create method gets called I get the NoMethodError "The error > occured while evaluating nil.new_record?" Why is product nil? How can > I access associated models in a validate method.The "unless @upc.upc.empty?" code will stop @upc.product being set to @product if upc is the empty string, so validate can''t see it. Why don''t you remove this condition and add a "validates_associated :upcs" line to Product, so that @product and its new upcs''s will only save if everything''s valid. -- We develop, watch us RoR, in numbers too big to ignore.
Eddie Hillenbrand
2006-Feb-10 15:47 UTC
[Rails] Re: accessing associated models in a validate method
On Feb 10, 2006, at 3:37 AM, Mark Reginald James wrote:> The "unless @upc.upc.empty?" code will stop @upc.product being set to > @product if upc is the empty string, so validate can''t see it. Why > don''t you remove this condition and add a "validates_associated :upcs" > line to Product, so that @product and its new upcs''s will only save if > everything''s valid.Even with "unless @upc.upc.empty?" commented out "product" is still nil in the validate method. The requirements for the app are such that a product can be created without a UPC, but once a product is saved a blank UPC can''t be added. If you know a way to do this with the validation class methods, please elaborate, I''d really like a better way to do this.
Mark Reginald James
2006-Feb-12 00:37 UTC
[Rails] Re: accessing associated models in a validate method
Eddie Hillenbrand wrote:> Even with "unless @upc.upc.empty?" commented out "product" is still nil > in the validate method. > > The requirements for the app are such that a product can be created > without a UPC, but once a product is saved a blank UPC can''t be added. > If you know a way to do this with the validation class methods, please > elaborate, I''d really like a better way to do this.Is it that a product''s UPC can start off blank, but once it''s set can''t return to being blank; or is it that the UPC must be set no later than the first save after creation? Also, try changing "product.new_record?" to "self.product.new_record?". That sometimes fixes these problems for reasons I can''t yet fathom. -- We develop, watch us RoR, in numbers too big to ignore.
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