Well at this point I'm not proposing nothing in particular, just trying to understand the rationale behind this relation between conversation scope and model driven, which is not clear to me why it is designed this way.
I thought that a possible explanation would be to keep the view (JSP) pages unaware of the scope of the variables it uses but honesty I'm not fully convinced of the gain I can achieve with this practice. I've developed a conversation scope interceptor I'm using in my projects and I don't use modelDriven interface. ModelDriven interface is (IMHO) uncomfortable because it is designed to return only one object for use in the view, which IMO is unrealistic but in the simplest use cases. In addition, if you want to use several objects in the view, it forces to either create a DTO (not good) to reunite all data or using a Map with domain objects but in either case you end up with something not very different to not using model-driven. 2008/3/4, Martin Gainty <[EMAIL PROTECTED]>: > Hi Gabriel- > > are your proposing an enhancement to s:head as i think this concept is > already covered by s:head which sets up global attributes? > http://struts.apache.org/2.0.6/docs/head.html > > or a separate "s:conversation" tag ? > > M- > ----- Original Message ----- > From: "Gabriel Belingueres" <[EMAIL PROTECTED]> > To: "Struts Users Mailing List" <user@struts.apache.org> > Sent: Tuesday, March 04, 2008 8:00 AM > Subject: Re: Conversation Scope? > > > > Why model-driven? I don't fully get it. > > I've done several S2 apps by now and never fell the time to use the > > model driven interface before (for me this is syntax sugar.) > > > > Now why is this important for supporting conversation scope? > > Is it for not writing code like > > ${conversationsMap[conversationId].myproperty} in the view? it is easy > > to create a tag that inject the conversation into a request-scoped > > variable like this: > > <s:conversation var="myconversation"/> > > > > then use ${myconversation.myproperty} > > > > Gabriel > > > > 2008/2/24, Jeromy Evans <[EMAIL PROTECTED]>: > > > I hadn't noticed this was already part of the 2.1.x core and default > stack: > > > > > > http://struts.apache.org/2.x/docs/scoped-model-driven-interceptor.html. > > > > > > I haven't checked the code but it reads the same > > > > > > Ray Clough wrote: > > > > I'm definitely going to have to watch the 'ranting'. (By the way, > > > > Adam, you have to stop grappling with SWF when you get married.) > > > > > > > > It seems to me that 'ModelDriven' is not much use without > > > > ConversationScope, because you have to manually manage the > > > > model/session interaction in all but the first action in the > > > > conversation. What I'm talking about with the term > > > > 'ConversationScope' is the need not to have to explicitly store, > > > > check, and remove my model data from the session in each action. > > > > Basically my action always looks like this: > > > > > > > > 1. check session for model. > > > > 2. if found, is model for the current conversation > > > > * if no delete the model from the session, create new model > > > > and place in session. > > > > * if yes place it into the Action's private variable > > > > 3. ...... whatever the action does ....... > > > > 4. is the conversation finished? > > > > * if no, make sure model is in session > > > > * if yes, remove model from session > > > > > > > > This seems like a pretty straight-forward use case for an > > > > interceptor. I'm thinking of a small object called > > > > "ConversationScope", which, of course, has to be stored in the > > > > session. The ConversationScope obj contains a map and a method to > > > > return its ConversationId, and methods to add and remove objects from > > > > its map. The interceptor could do to the ConversationScope the > > > > actions which the Action currently does, as delineated above. It > > > > might be nice to inject the ConversationScope into the action, but I > > > > don't personally know injection well enough to do that. A full > > > > solution with injection should have a "ConversationAware" interface > > > > which includes a "ConversationId" attribute. It might be better to > > > > use annotations rather than an interface declaration. > > > > > > > > I'm just thinking on paper here, but it doesn't seem like any massive > > > > over-architecting is needed. I personally have almost no experience > > > > with Spring, and every time I touch it everything breaks. Guice > > > > sounds like a nicer solution, but there is not much tutorial info on > it. > > > > > > > > Thanks, > > > > - rc > > > > > > > > > > > > Adam Hardy wrote: > > > >> Is it worth building a mechanism for conversation scope, compared to > > > >> the complexity it introduces? I really dislike Spring Webflow with > > > >> its conversation scope, stringent encapsulation and storage of > > > >> massive amounts of data in various maps that locks away everything > > > >> out of sight and makes it all taste like it's been massively > > > >> over-architected (and of course the practically insurmountable > > > >> learning curve) > > > >> > > > >> Isn't it just easier to clean your variables out of the session > > > >> manually when done? I'm not trying to provoke another rant, it's just > > > >> that I've suffered my fair share of pain grappling with SWF and I > > > >> find all justifications of its complexity unwarranted. > > > >> > > > >> Adam > > > >> > > > >> Ray Clough on 24/02/08 02:23, wrote: > > > >>> Thanks Jeromy. (usually my wife is the only one who notices my > > > >>> 'rants'). > > > >>> > > > >>> Jeromy Evans wrote: > > > >>>> Hi Ray, > > > >>>> > > > >>>> I'm not sure, but check out Tom's new scope plugin as it may get > > > >>>> you part of the way there. > > > >>>> > > > >>>> http://cwiki.apache.org/S2PLUGINS/scope-plugin.html > > > >>>> > > > >>>> I was just reading one of your rants from August 07 that mentioned > > > >>>> the need to use ModelDriven's model across a conversation and think > > > >>>> this will be useful. > > > >>>> > > > >>>> cheers, > > > >>>> Jeromy Evans > > > >>>> > > > >>>> Ray Clough wrote: > > > >>>>> JSF has a "ConversationScope" for extended series of > > > >>>>> requests/responses > > > >>>>> dealing with the same topic, and usually the same data model. I'm > > > >>>>> thinking > > > >>>>> of writing an interceptor to simulate ConversationScope, and I'm > > > >>>>> wondering > > > >>>>> if this has not already been done, and if so, does anyone have > > > >>>>> details, > > > >>>>> code, etc. > > > >> > > > >> > > > >> --------------------------------------------------------------------- > > > >> To unsubscribe, e-mail: [EMAIL PROTECTED] > > > >> For additional commands, e-mail: [EMAIL PROTECTED] > > > >> > > > >> > > > > > > > > --------------------------------------------------------------------- > > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
