Sean Wolfe
2005-Dec-12 21:03 UTC
has_many << method returns a class with the wrong base type.
I posted this originally on the comp.lang.ruby newsgroup, but I was told to bring it here. I have a layered one to many relationship situation that is having some weird problems. I've been trying to look for a solution but I can't seem to find it, or am not certain what keywords I should search on. Okay lets explain the environment. A Ruby on Rails app, simple CMS. Just some little tweaks. But versioning needs to be supported, and some articles require that the body can have multiple pages. Also the Articles can have multiple types, so they use a Single table inheritance scheme. So I have the following classes. class Article < ActiveRecord::Base has_many :versions def new_version(properties = {}) self.pinned_version += 1 properties[:version] = self.pinned_version self.versions << Version.new(properties) end end class News < Article end # there are other sub classes of articles but for brevity I only display one for example. class Version < ActiveRecord::Base belongs_to :article has_many :article_pages end class ArticlePage < ActiveRecord::Base belongs_to :version end Now in my controller, I have a method that works like this... # Method to create a new Article. Create's it with the initiated type # and creates the first version of the Article. def create @article = create_typed_article(params[:article]) @version = @article.new_version(params[:version]) params[:article_page].each do |page_name, page_data| page = ArticlePage.new() page.page_number = page_name.match(/\d+/)[0] page.body = page_data @version.article_pages << page end if @article.save flash[:notice] = 'Article was successfully created.' redirect_to :action => 'list' else render :action => 'new' end end Now the problem is, on the line "@version.article_pages << page", I get the following error: undefined method `article_pages' for Version:Class But if I open up the console, and do the following... v = Version.find(:conditions => ['version = ? AND article_id = ?', 1, 1]) v.article_pages It works just fine. Now looking more closely at the error, it appears that the Version object that is returned by new_version inherits from Class instead of ActiveRecord::Base. Therefore it doesn't seem to have the collection of ArticlePage objects. Well, it seems that the problem is that the @version.article_pages << method returns an object with the wrong base type. Other methods from the collection such as find and the index return an object with the right base type. I guess I can change my method to this: def new_version(properties = {}) self.pinned_version += 1 properties[:version] = self.pinned_version version = Version.new(properties) self.versions << version version end But that just seems to circumvent some of the niceities of the Ruby language, and might as well be programming in Java or C#. Anyone else run into this problem? Is there a solution? Is this a bug, or by some sort of wicked design? Thanks, -- Sean Wolfe master nerd of i heart squares, Co. 3711 N. Ravenswood Ave. #147 Chicago, IL 60613 Ph. (773) 531-6301 Fx. (773) 529-7041 http://www.iheartsquares.com _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
Eero Saynatkari
2005-Dec-12 22:07 UTC
Re: has_many << method returns a class with the wrong base t
Sean Wolfe wrote:> I posted this originally on the comp.lang.ruby newsgroup, but I was told > to > bring it here. > > I have a layered one to many relationship situation that is having some > weird problems. I''ve been trying to look for a solution but I can''t > seem to find it, or am not certain what keywords I should search on. > Okay lets explain the environment. A Ruby on Rails app, simple CMS. > > <snip> > > Now in my controller, I have a method that works like this... > > <snip> > > Now the problem is, on the line "@version.article_pages << page", I get > the following error: > undefined method `article_pages'' for Version:Class > > But if I open up the console, and do the following... > v = Version.find(:conditions => [''version = ? AND article_id = ?'', 1, > 1]) > v.article_pages > > It works just fine. Now looking more closely at the error, it appears > that the Version object that is returned by new_version inherits from > Class instead of ActiveRecord::Base. Therefore it doesn''t seem to have > the collection of ArticlePage objects. > > Well, it seems that the problem is that the @version.article_pages << > method > returns an object with the wrong base type. Other methods from the > collection such as find and the index return an object with the right > base > type. > > <snip>The problem, by the way, seems to be that ''Version:Class'' error, which indicates that the method called is Version.article_pages, not Version.new.article_pages as it should. Some more framework knowledge is required for figuring out why this is the case.> Thanks, > Sean WolfeE (from ruby-talk) -- Posted via http://www.ruby-forum.com/.
Sean Wolfe
2005-Dec-12 23:02 UTC
[solved] has_many << method returns a class with the wrong base t
On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:> > > > <snip> > > The problem, by the way, seems to be that 'Version:Class' error, > which indicates that the method called is Version.article_pages, > not Version.new.article_pages as it should. > > Some more framework knowledge is required for figuring out why > this is the case.First off, why do you have to be so rude in your answer. Secondly, your answer is wrong. Actually looking at the return value, it's an Array. Version.new() is called, and creates a new object of type Version. That object is then added by the Article.article_pages << method. This method adds the object to the array of Version objects, then it returns the actual Article.article_pages objec with the new Version object added to it. So actually the correct answer would be on the other end of the new_version method I should then grab the last item in the array. Or I can simply change my new_version method to: def new_version(properties = {}) self.pinned_version += 1 properties[:version] = self.pinned_version (self.versions << Version.new(properties))[-1] end I just didn't notice the little "[" before the returned "#<Version:0x3804048 ... " when i first was investigating the problem. It would have been easy to just remind me that my assumption that the << method returns the object added instead of the actual object. But instead you deside to act like a know it all, and give me a wrong answer. Understand the problem first before making such rude responses publicly. -- Sean Wolfe master nerd of i heart squares, Co. 3711 N. Ravenswood Ave. #147 Chicago, IL 60613 Ph. (773) 531-6301 Fx. (773) 529-7041 http://www.iheartsquares.com _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
Eero Saynatkari
2005-Dec-12 23:33 UTC
Re: [solved] has_many << method returns a class with the wro
Sean Wolfe wrote:> On 12/12/05, Eero Saynatkari <ruby-forum-reg-hRtevi7K+EU+Va1GwOuvDg@public.gmane.org> wrote: >> >> >> > <snip> >> >> The problem, by the way, seems to be that ''Version:Class'' error, >> which indicates that the method called is Version.article_pages, >> not Version.new.article_pages as it should. >> >> Some more framework knowledge is required for figuring out why >> this is the case. > > > First off, why do you have to be so rude in your answer.I am sorry if I came across that way; I was trying to explain what ruby was able to discern and why this might be the right place instead of ruby-talk.> Secondly, your answer is wrong. Actually looking at the return value, > it''s > an Array."undefined method `article_pages'' for Version:Class" refers to a situation like (you can test this in irb): class Version end Version.article_pages It is certainly possible that there are other issues, but this a strict interpretation of the error. I am not knowledgeable of any other issues, which is why this forum is probably better for further inquiries.> Version.new() is called, and creates a new object of type Version. > That object is then added by the Article.article_pages << method. This > method adds the object to the array of Version objects, then it returns > the > actual Article.article_pages objec with the new Version object added to > it. > > So actually the correct answer would be on the other end of the > new_version > method I should then grab the last item in the array. Or I can simply > change > my new_version method to: > > def new_version(properties = {}) > self.pinned_version += 1 > properties[:version] = self.pinned_version > (self.versions << Version.new(properties))[-1] > end > > I just didn''t notice the little "[" before the returned > "#<Version:0x3804048 ... " when i first was investigating the problem. > > It would have been easy to just remind me that my assumption that the << > method returns the object added instead of the actual object. But > instead > you deside to act like a know it all, and give me a wrong answer. > Understand > the problem first before making such rude responses publicly.Just attempting to help you based on the information you provided. Sorry again. Is the problem solved or is this just a workaround?> Sean WolfeE -- Posted via http://www.ruby-forum.com/.
Sean Wolfe
2005-Dec-13 00:23 UTC
Re: Re: [solved] has_many << method returns a class with the wro
On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote: <snip>> > > > First off, why do you have to be so rude in your answer. > > I am sorry if I came across that way; I was trying to explain > what ruby was able to discern and why this might be the right > place instead of ruby-talk.Okay, sorry for gunning off there.> > Secondly, your answer is wrong. Actually looking at the return value, > > it's > > an Array. > > "undefined method `article_pages' for Version:Class" refers to > a situation like (you can test this in irb): > > class Version > end > > Version.article_pagesRight, but my problem was an assumption of how the << method worked. The following IRB clued me in:>> a = Article.new=> #<Article:0x38130c0 @attributes={"sub_category_id"=>nil, "last_modified_at"=> nil, "type"=>"RecordReview", "approved"=>0, "assignment_id"=>nil, "pinned_versio n"=>0, "author_id"=>nil, "published_at"=>nil, "read_count"=>0, "created_at"=>nil }, @new_record=true>>> a.versions=> []>> v= a.new_version=> [#<Version:0x3807ca8 @attributes={"rating"=>nil, "artist"=>nil, "bside_artist "=>nil, "store_link"=>nil, "abstract"=>nil, "title"=>"", "release_year"=>nil, "b est_new_music"=>0, "record_label"=>nil, "version"=>1, "genre"=>nil, "bside_title "=>nil, "coverpic_id"=>nil, "article_id"=>0, "image_id"=>nil, "source"=>nil}, @n ew_record=true>]>> v.class=> Array Now I could see that v was actually an array containing Version object. Didn't see those little bracket thingies. After realizing that it was an Array, I was able to go back and re-read the Array << method description in "Programming Ruby". Despite my numerous reads before, I then realized that I had a misconception about that method, in which I thought it returned the added object, when in reality it returns the whole array with the added object. I think I had the result confused with another method but I'm not quite sure which at the moment, since all i see as far as return values for most Array methods is the Array instance itself, or a new array instance.> It is certainly possible that there are other issues, but > this a strict interpretation of the error. I am not knowledgeable > of any other issues, which is why this forum is probably better > for further inquiries.Array does not have the article_pages method. Which would give me the error i was having, except I do not understand why it said Version:Class when the error should be something like "undefined method `article_pages' for []:Array" Which in the following IRB is exactly what I get:>> b = []=> []>> b=> []>> b.class=> Array>> b.somethingNoMethodError: undefined method `something' for []:Array from (irb):9 <snip>> Just attempting to help you based on the information > you provided. Sorry again. > > Is the problem solved or is this just a workaround?Yes, sorry for the little heated exchange. You did help, but I just misunderstood your tone. I was able to solve it by changing the new_version method to act how I wished with as few lines as I was expecting def new_version(properties = {}) self.pinned_version += 1 properties[:version] = self.pinned_version (self.versions << Version.new(properties))[-1] end -- Sean Wolfe master nerd of i heart squares, Co. 3711 N. Ravenswood Ave. #147 Chicago, IL 60613 Ph. (773) 531-6301 Fx. (773) 529-7041 http://www.iheartsquares.com _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails