Problem with Checkboxes
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Hey,
first, I am a Squeak/Smalltalk newcomer, so please forgive me if I make an obvious error. I also give as much detail as I can and would greatly appreciate general comments. I am trying to write a small survey application, for that I created a class WASurvey: WAComponent subclass: #WASurvey instanceVariableNames: 'survey questionsPerPage currentPage' classVariableNames: '' poolDictionaries: '' category: 'questionaire' survey is a list of questions, questionsPerPage/currentPage should be obvious. The component is rendered like that: renderContentOn: html | first last | first := currentPage - 1 * questionsPerPage + 1. last := first + questionsPerPage - 1. html heading: survey title. html text: currentPage; text: '/'; text: self pageCount. html form: [ survey questions from:first to:last do: [ :question | question renderContentOn: html ]. html submitButton text: 'Previous Page'; callback: [ currentPage := currentPage - 1 ]; disabled: currentPage = 1. html submitButton text: 'Next Page'; callback: [ currentPage := currentPage + 1 ]; disabled: currentPage = self pageCount. ] Now I created several Question classes that implement renderContentOn: aCanvas MultiChoiceQuestion>>renderContentOn: html super renderContentOn: html. answers doWithIndex: [ :answer :index | | current | current := html checkbox value: (values includes: index). html text: answer. ] SingleChoice>>renderContentOn: html super renderContentOn: html. html radioGroup: [ :group | answers doWithIndex: [ :e :index | | current | current := group radioButton. value = index ifTrue: [ current beChecked ]. html text: e ] ] I currently get a MessageNotUnderstood error that seems to be related to the Checkbox components in MultiChoice questions. My problem is, that the StackTrace is very deep, and only shows Seaside internals. What would now be the general approach to trace down that issue? Thanks for your help, Felix Here is the top of the Stack Trace: 1. thisContext <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&4> UndefinedObject(Object)>>doesNotUnderstand: #value: self <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&5> nil aMessage <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&6> value: nil 2. thisContext <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&7> [] in WACheckboxTag>>after {[callback value: value. value := false]} self <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&8> a WACheckboxTag 3. thisContext <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&9> BlockContext>>valueWithPossibleArgument: self <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&10> [] in WACheckboxTag>>after {[callback value: value. value := false]} anArg <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&11> '' 4. thisContext <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&12> WAValueCallback>>evaluateWithArgument: self <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&13> a WAValueCallback anObject <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&14> '' 5. thisContext <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&15> WAValueCallback(WACallback)>>evaluateWithField: self <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&16> a WAValueCallback anObject <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&17> '' _______________________________________________ seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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So in the top frame of the stack you can see that the error is #value:
being called on nil. If you look at the second frame, you can see that #value is being called on the instance variable 'callback', so clearly that must be nil. And sure enough, if you look at your rendering code, you have not set a callback for your checkboxes (if you don't set a callback, you won't get the value submitted by the user). If you add a call to #callback: when rendering your checkbox the problem should go away. That said, obviously the framework should handle the case of no callback more gracefully. I created the following issue: http://code.google.com/p/seaside/issues/detail?id=106 Welcome to Seaside, Julian On Sun, Jul 20, 2008 at 7:46 AM, Felix Dorner <[hidden email]> wrote: > Hey, > > first, I am a Squeak/Smalltalk newcomer, so please forgive me if I make an > obvious error. I also give as much detail as I can and would greatly > appreciate general comments. > > I am trying to write a small survey application, for that I created a class > WASurvey: > > WAComponent subclass: #WASurvey > instanceVariableNames: 'survey questionsPerPage currentPage' > classVariableNames: '' > poolDictionaries: '' > category: 'questionaire' > > survey is a list of questions, questionsPerPage/currentPage should be > obvious. > > The component is rendered like that: > > renderContentOn: html > | first last | > first := currentPage - 1 * questionsPerPage + 1. > last := first + questionsPerPage - 1. > html heading: survey title. > html text: currentPage; text: '/'; text: self pageCount. > html form: [ > survey questions from:first to:last do: [ :question | question > renderContentOn: html ]. > html submitButton text: 'Previous Page'; > callback: [ currentPage := currentPage - 1 ]; > disabled: currentPage = 1. > html submitButton text: 'Next Page'; > callback: [ currentPage := currentPage + 1 ]; > disabled: currentPage = self pageCount. > ] > > Now I created several Question classes that implement renderContentOn: > aCanvas > > MultiChoiceQuestion>>renderContentOn: html > super renderContentOn: html. > answers doWithIndex: [ :answer :index | > | current | > current := html checkbox value: (values > includes: index). > html text: answer. > ] > > SingleChoice>>renderContentOn: html > super renderContentOn: html. > html radioGroup: [ :group | > answers doWithIndex: [ :e :index | > | current | > current := group radioButton. > value = index ifTrue: [ current beChecked > ]. > html text: e ] > ] > > > I currently get a MessageNotUnderstood error that seems to be related to the > Checkbox components in MultiChoice questions. My problem is, that the > StackTrace is very deep, and only shows Seaside internals. What would now be > the general approach to trace down that issue? > > Thanks for your help, > > Felix > > Here is the top of the Stack Trace: > > 1. > > thisContext > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&4> > UndefinedObject(Object)>>doesNotUnderstand: #value: > self > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&5> > nil > aMessage > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&6> > value: nil > > 2. > > thisContext > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&7> > [] in WACheckboxTag>>after {[callback value: value. value := > false]} > self > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&8> > a WACheckboxTag > > 3. > > thisContext > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&9> > BlockContext>>valueWithPossibleArgument: > self > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&10> > [] in WACheckboxTag>>after {[callback value: value. value := > false]} > anArg > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&11> > '' > > 4. > > thisContext > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&12> > WAValueCallback>>evaluateWithArgument: > self > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&13> > a WAValueCallback > anObject > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&14> > '' > > 5. > > thisContext > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&15> > WAValueCallback(WACallback)>>evaluateWithField: > self > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&16> > a WAValueCallback > anObject > > <http://127.0.0.1:8080/seaside/survey?_s=TGzVOKjnplpRtUnu&_k=VXYqwquh&17> > '' > > > _______________________________________________ > seaside mailing list > [hidden email] > http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside > seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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In reply to this post by Felix Dorner
> WAComponent subclass: #WASurvey
another remark:
> instanceVariableNames: 'survey questionsPerPage currentPage' > classVariableNames: '' > poolDictionaries: '' > category: 'questionaire' > > survey is a list of questions, questionsPerPage/currentPage should be > obvious. > > The component is rendered like that: > > renderContentOn: html > | first last | > first := currentPage - 1 * questionsPerPage + 1. > last := first + questionsPerPage - 1. > html heading: survey title. > html text: currentPage; text: '/'; text: self pageCount. > html form: [ > survey questions from:first to:last do: [ :question | question > renderContentOn: html ]. [:question | html render: question] "It's important that you use #render:, rather than directly calling the #renderContentOn: method of the subcomponent. " if question is a component (then don't forget to use children). If Question is not a subclass of WAComponent, then implement renderOn: instead of renderContentOn: hth Cédrick _______________________________________________ seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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In reply to this post by Julian Fitzell-3
Hi Julien,
> If you add a call to #callback: when rendering your checkbox the > problem should go away. That said, obviously the framework should > handle the case of no callback more gracefully. I created the > following issue: http://code.google.com/p/seaside/issues/detail?id=106 > Great. I simply assumed that not setting a callback would not break anything. (I didn't set a callback for the radio button (group) either, and didn't have problems there). I simply wanted to add the callbacks in a second step, and definitely agree that a nil callback shouldn't cause a problem. Thanks for helping, Felix _______________________________________________ seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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In reply to this post by cedreek
Hi Cdric,
>> html form: [ >> survey questions from:first to:last do: [ :question | question >> renderContentOn: html ]. >> > > another remark: > > [:question | html render: question] > > "It's important that you use #render:, rather than directly calling > the #renderContentOn: method of the subcomponent. " if question is a > component (then don't forget to use children). > advice, I'll keep that in mind. > If Question is not a subclass of WAComponent, then implement renderOn: > instead of renderContentOn: > Why? Simply to avoid confusion? Thanks, Felix _______________________________________________ seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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On Mon, Jul 21, 2008 at 11:04 PM, Felix Dorner <[hidden email]> wrote:
>> If Question is not a subclass of WAComponent, then implement renderOn: >> instead of renderContentOn: >> > > Why? Simply to avoid confusion? Because then you can pass it to "html render:" :) Any object that is renderable should implement #renderOn:. WAComponent implement that to do a bunch of other stuff and then calls #renderContentOn: for its subclasses. Obviously if you're the only one using your class, you can call it #fooBarBaz: if you feel like, but if you implement #renderOn: you can do: html render: aCollectionOfQuestions or: html div id: 'foo'; with: aQuestion And yes, it's just sort of standard I guess. Julian _______________________________________________ seaside mailing list [hidden email] http://lists.squeakfoundation.org/cgi-bin/mailman/listinfo/seaside |
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