I am using GWT-Platform and I read in PresenterWidget document that it is possible to implement multiple views with single PresenterWidget.
I am not getting idea how should I do that? Can anyone please provide insights how to so that?
Any working example will help better.
Thanks.
As mentioned in the comment, you can find a sample on how to achieve that, here
I believe their strategy is to group their presenters along with different GIN modules (i.e. Presenter X with view A1 go to GinModule1, Presenter X with view A2 go to GinModule2, etc).
Then they install one GIN module or the other, depending on some user agent parameter (in GWT you can do deferred binding via *.gwt.xml file).
This works well for them because they have this setup so they can have different views for mobile, tablet, desktop, etc, but the same presenters; therefore, the binding based on user-agent works well).
On another note, I think it is possible to bind through other mechanisms, but you need advanced GIN-fu skills here, and it's not really my area (but I'm fairly sure a colleague of mine mentioned this recently).
Related
I am loving MvvmCross so far, but I am new to the MVVM technique. MVVM seems to center around the View and ViewModel and navigating between them. However, what about application-wide model items? Maybe my application has a mode that it can be in that affects all views and viewmodel behavior. This seems like an ApplicationModel or ApplicationViewModel. Or maybe just use the App class itself to store application wide stuff? What is the recommended practice for this concept? If using the App class itself is a good idea, I assume there is an easy way to get a hold of the reference to the App instance from anywhere? Haven't looked yet.
A ViewModel is a Model for a View - so that's where the current MvvmCross focus sits.
For this application wide behaviour, I think it's best to consider it one use case at a time.
The example you've provided is:
Maybe my application has a mode that it can be in that affects all views and viewmodel behavior.
There's not much detail here, but for this type of thing I might perhaps:
place this Mode inside a Singleton service
would use a messenger to send ModeChangedMessages when the Mode changed
would provide that service and the messenger to the relevant ViewModels using constructor injection
the ViewModels can then subscribe for ModeChangedMessage on the messenger
would perhaps use inheritance in my ViewModels to share code between them (ie they'd inherit from a BaseViewModel class)
There are of course other ways to do this, but that's one suggestion
If there's some other application wide use case you'd like to ask about, please ask another question - but please include more detail - eg perhaps provide some pseudo-code about what you want to share. I find real use cases easier to work out - abstract ideas are harder to talk about.
If it helps:
There's an introduction to services and constructor injection in N=2 on http://mvvmcross.wordpress.com
There's an introduction to the Messenger on N=9 in http://mvvmcross.wordpress.com
I have great experience in programming by using java and other languages.
I need anyone who has great experience in using GWT with MVP to explain how to build GWT Application using MVP:
View package : explain what should be in view class.
Client Package: explain what java files are supposed to be here and what is the benefit from each file.
Server Package: I think here all services files( RPC ).
Activity Package: Explain what is the benefit from the classes here , I think here we we connect events with controls in view classes( Am I correct?).
Place Package: I need to understand this very well.
Also what is the benefit from Clientfactory java file?
what is eventbus?
what is placecontroller?
please if you can order which file should be coded one after another?
Thank you in advance,
1) View is a widget with link to its presenter. It should notify presenter about ui events which should be processed.
2) Views, presenters, client(not shared with the server side) model, places, activities, PlaceHistoryMapper, ActivityMapper. About benefits see below.
Are you understand presenters well? According to your question i assume you confuse it with activities.
1.1 ) Presenter creates and manages view, makes rpc and most of 'logic' stuff.
3) You are right, server package is just a java server logic.
4) Activities link places and presenters. I will return to describing activities below.
5) Place has name, token and own Tokenizer which transforms its place to a token and other way round.
6) I didn't use ClientFactory. I prefer dependency injection with google-gin(gwt client version of guice)
7) Event bus is... I couldn't describe better than official javadoc does :)
Dispatches Events to interested parties. Eases decoupling by allowing objects to interact without having direct dependencies upon one another, and without requiring event sources to deal with maintaining handler lists. There will typically be one EventBus per application, broadcasting events that may be of general interest.
8) PlaceController knows where you are(in application :) and may change current place. (obviously, it has getWhere() and goTo(Place) methods)
9) Firstly you need to code application's singletones like PlaceHostoryMapper and ActivityMapper.
PlaceHostoryMapper provides history and converting tokens to places by segregating all PlaceTokenizers.
ACtivityMapper segregates all places and activities and provides second ones by first ones.
Views and presenters are based on interfaces. Next I would declare such interfaces.
Then write places. Then you able to code activities because you have places and interfaces of presenters.
Then in any order implement views and presenters, map activities to places in ActivityMapper and register PlaceTokenizers in PlaceHistoryMapper.
I assume now you have more questions, feel free to ask in comments or by contacts in my profile :)
I have read a lot of gwt-mvp questions that are asked here, but since i'm totally new to this design pattern I would like to ask some questions:
[1] The Activity-Place pattern is a different pattern than mvp?
[2] In the MVP pattern presenters contain the logic. Now the logic of the widgets/controls is defined in the Activities?
[3] The CustomPlace classes are fixed (as the Eclipse plugin constructs them) or can i put data/methods and what kind?
[4] What is the use of the Presenter interface inside a CustomView? What data/methods would make sense to add into it?
[5] I want to build an application that will use many data structures that will be saved into a database. I have read some other posts here and I will make the Model part of MVP live inside each Activity. So i think to create each time the data structures of each activity at start and load its values (if necessary from db) and will update the database after the user goes to another view. What do you think about this approach?
Let's start by debunking one myth: Activities/Places have nothing to do with MVP. Places is about navigation, Activities are about "componentizing" the UI wrt Places. On the other hand, MVP is a design pattern, it's about how to organize your code.
Many people are using their activities as their MVP-presenters, but it's not enforced. The GWT team is trying a new approach where the activity is distinct from the presenter (work underway in the mobilewebapp sample if you want to follow what's going on there). You could also have your activity being your view and making use of an "internal" presenter (similar to how Cell widgets work)
A Place is more or less a URL. You can put whatever you want in it. I'd suggest making places immutable though: build a Place, goTo it, make use of its properties to build your UI.
That's about MVP then. This is only needed to decouple your view and presenter, mostly to make mocking in unit tests easier (this is particularly of the view interface though, not much for the presenter one, unless writing a test harness for you views). In some cases, you might also want to use the same view with distinct presenters; they'll all implement the same interface so the view can talk back to them.
How about the closing of the window/tab? I'd rather use a periodic auto-save, or an explicit save button; and implement mayStop so it prompts the user when there are unsaved changes (similar to how most desktop office apps work —e.g. MS Word or LibreOffice—, and GMail if you try to navigate away before your mail draft is auto-saved)
The Activity-Place is an implementation of the pattern. Google introduced gwt-mvp pattern at Google IO, but only provided it's implementation as part of GWT about a year later.
Yes Activities contain business logic. No, widgets/controls usually do not contain any logic, they just fire events based on user action. The logic that acts upon those events is written by user and resides elsewhere.
I don't use Eclipse, so wouldn't know about Places generated by it. Normally custom Places can contain custom fields and methods. For example they can contain custom place token arguments, i.e. if place token is "#place:id1", than your custom Place could contain field holding this argument.
When View needs to call/access Activity, it does so via Presenter, which Activity implements. For example when user enters all data in a for and presses submit, then you could have a method in Presenter named submit(formData).
Preparing/loading data in activity.start(..) is a normal way of doing things. If particular activity is used a lot, then you might consider caching the data if appropriate.
I'm in the middle of converting an existing app built on top of zend framework to work as a plugin within wordpress as opposed to the standalone application it currently is.
I've never really used zend so I've had to learn about it in order to know where to begin. I must say that at first I didn't think much of zend, but it's funny because the more I understand how it works the more I keep questioning why I'd want to remove dependency when it's a clearly well thought out framework. Then I'm reminded that it's because of wordpress.
Now I already know there are WP plugins to make zend play nice with WP. In fact I'm aleady using a zend framework plugin just to get the app functional within the WP admin area which is allowing me to review code, modify code, refresh the browser, review changes, debug code, again and again.
Anyway, I really don't have a specific question but instead I'm looking for advice from any zend masters out there to offer advice on how to best go about a task like this one.... so any comments, advice, examples or suggestions would be super.
One area I'm a little stuck on is converting parts of zend->db calls to work as wpdb calls instead... specifically the zend->db->select.... not sure what to do with that one.
Also on how to handle all the URL routing with automatic calls to "whatverAction" within thier respective controllers files.
Any help would be great! Thanks
You're probably facing an uphill battle trying to get some of the more major components of ZF to work in harmony with Wordpress. It sounds like you've got a full MVC app that you're trying to integrate into a second app that has very different architecture.
You probably want to think about which components handle which responsibilities. Wordpress has it's own routing and controller system that revolves around posts, pages and 'The Loop'. This is entirely different from Zend's Action Controllers and routing system.
It's possible you could write a WP hook to evaluate every incoming request and decide if it should be handled by WP or a ZF controller. However, it is doubtful you would be able to replace WP's routing system outright with ZF's or vice versa.
Same idea, where Zend_Db is concerned. There's nothing stopping you from using Zend_Db to access Wordpress's database, but trying to somehow convert or adapt Zend_db calls into wpdb calls sounds painful. If you have a large model layer, you probably want to hang on to it, and find a way to translate data from those models into the posts/pages conventions that Wordpress uses.
Personally, I would use ZF to build a robust business layer that can be queried through an object model via a Wordpress plugin, and then rely on Wordpress to do the routing and handle the views.
Zend_DB_Select is simple SQL query (but created using objects) that can be used like any other query. Just turn it into string. Ex.:
mysql_query((string)$zendDbSelectObject);
I've been thinking about this recently and I don't know a really nice and tidy way of creating a mobile version of an existing or new MVC2 website/app.
I think the easiest way would be to just use a different stylesheet depending on whether a mobile was detected but sometime you need to change the view content too if you have massive inline images everywhere or for other reasons.
What is a good approach for this? Is there a way of theming fairly easily in MVC2?
Well MVC is just your server-side technology, what you should ask to yourself is "what is the best practice to create a mobile web site, regardless of the server side tech".
In my opinion, creating a well-formed and semantic (x)html is the first step. As you say, the most logical thing to do is create different style sheets for different media types, and you're right.
As for the problems you mention, like inline images, consider this: are those images content or presentation?
In the first case, they should be present even in the mobile version.
In the latter, they are defined in the style sheet, so you can simply avoid them in the mobile css.
The only exception I can think of is when you want to provide different functionality on mobile, or if you're forced to, i.e. on pages that rely heavily on JS and those scripts wouldn't run on mobile browsers. In this case, you might want to create different versions of those pages and serve the appropriate version based on the user agent.
Check the source code for NerdDrinner. They've implementated a MobileCapableWebFormViewEngine class which inherits from base WebFormViewEngine class. The MobileCapableWebFormViewEngine uses the HTTPContext to decide which View to render in the client. This'll make more sense when you see the source code