I am building a website based on widgets. I have a general WidgetInstancesController class with several methods, a model and some views for it. Now, I want to know if it's possible to extend this class. In other words, each widget should be another class, extending the WidgetInstancesController class. I want to store these widgets classes under app/widgets/. Also, these widgets won't have any specific model (as they will use the parent WidgetInstance model) but may have some specific views.
Any suggestions on how can I do this will be highly appreciated!
I would suggest building them as components, but it can be done in other ways.
I have had to do something similar where I built a CMS with add-on modules. To make it work logically, I had to turn MVC on its head a little and go for a very thin controller. Essentially, the front-end module logic was contained entirely at the Model level, with the associated views as elements. A module helper fetched and displayed the module in the public front-end. The back-end was handled conventionally via MVC with a normal fatness controller.
As it turned out, the Models were surprisingly lightweight and having everything as elements made usability a dream.
Related
I have developed a WPF application using Prism and Unity frameworks and I have some concerns regarding the following whether I have implemented them correctly or not.
Abstract classes / Interfaces - I have organized interfaces for all the layers in one assembly and then referenced it in the respective library for implementation. Now, the referenced library has access to all the non required interfaces of other layers. For e.g. the service layer has access to UI interfaces. Is this the proper implementation in terms of clear separation or should I split it into multiple assemblies.
View Model dependencies - I used EventAggregator mostly to communicate between view models. In some cases, I am passing the instance of other view models directly in the constructor and resolving it using DI container. I want to omit the direct view model dependency by introducing the interface to achieve clear separation. How can I organize the interface for view models into a separate assembly in such a way that the other developers could understand.To avoid creating multiple UI projects, I created only one single assembly and logically separated them into folders.
Abstract Module Class - Instead of specifying all the dependencies in bootstrapper.cs file, I factored them in respective module. Most of my class lib projects has references to Prism libraries. Thus, UI specific namespaces are added to non UI related projects. Is there any better approach to achieve this ?
Abstract classes / Interfaces
I'd go for exactly as many "interface-assemblies" as necessary, having too many of them hurts. Example: if you need to prevent layer 1 from potentially communicating with layer 3, put the layer 1-to-layer 2-interfaces in one assembly and those for layer 2-to-layer 3 in another one.
View Model dependencies
Normally, you shouldn't need to pass view models around at all. Pass around the data (a.k.a. model), the view models themselves don't hold any data that's either unavailable elsewhere or valuable to anyone but the view bound to the view model.
Abstract Module Class
Your prism application references prism... so what? As long as only the IModule implementations receive the IUnityContainer I wouldn't care at all. If someone needs to publish an event, he get's the IEventAggregator... That's an interface already, and you can inject a mock in your tests, so no need for further abstraction.
I need to convert the following AngularJS application to a GWT application (though the question applies to any angular application). I would like to use the MVC pattern and UiBinder as suggested in the documentation but I'm unsure as to how the components of the angular application should correspond to the GWT one.
I've given it some thought already and here's my understanding - I'd be grateful if someone could say if I've got it right
Each module should become a presenter
One view per presenter
Services must be initialised in the AppController and passed to the relevant presenters (similarly to how an eventBus is implemented in the MVC description)
Now I don't know how to put multiple presenters together, though, so that they create one page. Should I create a main view that would correspond to the AppController and then pass the relevant parts of that view to each presenter?
Also, what's the best way to handle modal dialogs? Should I just include them in the view, bind to the presenter and keep them hidden initially?
I would recommend to use either Activities and Places or a fully fledged MVP framework like GWTP.
Regarding your questions:
I think that's right
One view per presenter is the usual approach. However you can also think of implementing different views for different devices (Desktop, Mobile, etc).
I would recommend to use a dependency injection framework like GIN to inject services and components into your Presenters
It depends if you use Activities and Places or GWTP. GWTP has the conecept of PresenterWidget that can be nested in Presenters. For Activities and Places you can follow Thomas Broyer's recommendation.
In general I think Presenters and their corresponding Views should be standalone components that are usually associated with a Place. GWTP has the concept of Slots (i.e. side navigation, etc) where Presenters can reveal themselves.
Communication between Presenters should be done via the EventBus.
GWTP has a concept of PopupPresenters but typically I think modal dialogs should be included in the View and handled by the parent Presenter (unless it contains a lot of business logic).
You said:
Each module should become a presenter
look at [GWT Organize Projects][1]http://www.gwtproject.org/doc/latest/DevGuideOrganizingProjects.html
It talks about modules in the section, "Modules: Units of Configuration"
Basically, a module is just for configuration. You need a module for each entry point. People often have 1 module per page.
You said:
One view per presenter
This is usually the case.
You said:
Services must be initialized in the AppController and passed to the relevant presenters (similarly to how an eventBus is implemented in the MVC description)
Like Ümit said you should use Gin
Ümit recommended GWTP I'm no expert on GWTP but I used it briefly when I was a beginner and it was hard. I don't think it's good for beginners. Admittedly, it might be worth the investment of learning it. Like I said I'm no expert on GWTP.
I have defined a model within it I have default model schema. I have a respective collection and views defied for it.
I have the model data stored as documents in Couchdb.My question is, How can I render these items in a browser.
I guess I am missing something small here with regard to linking the db and backbone.js. A little bit of direction would be very helpful.
To display/visualize the data you need views. Backbone.js provides a very skinny views layer with no magic in built. So in almost all but the most simplest cases you would like to auxiliate your mvc architecture with some user interface widget framework like YUI to provide UI components like datagrid or visualization toolkits to provide graphs and charts.
Of course you can stitch in plugins or create your own ui components in the view layer.
Backbone.js provides absolute freedom of choice to you to use whatever ui components you like in your views and unlike sproutcore/ cappuccino does not provide a hardwired ui framework.
So you would create view classes that perform the job of rendering the ui elements either by doing the hardwork themselves or by delegating them to some external library. In a typical scenario you will have nested views to provide a robust and responsive application interface. Eg. in a gridview you can have a master view for the whole table and views representing individual rows. If you are using sophisticated cell renderers then you can have the cell rendering logic in further nested views.
I have an app that has several modules that have completely different functionality and I'm trying to figure out the best way to implement this using prism.
To try and better explain, I'll try to use Northwind as an example. I have 3 modules, orders, customers & employees.
The customer module will allow you to do anything pertaining to a customer. Add, remove and edit. I'm going to use scope regions for the main view in the customer module to handle all the different views I need to show here.
In the scenario above, I only want to load a module when a user wants to work with say a customer, order or employee.
You have these modules laid out and realize that you need to be able to show Orders for customer or sales people which are obviously employees.
What would you do here in this scenario as you wouldn't want to create an entirely new modules for say employeeOrders and customerOrders and you wouldn't want to duplicate any order related code.
I'm starting to wonder if it's feasible to think about building a composite application using prism if you're building an app like Outlook, but for a LOB business app, I've yet to find a good sample of how to do this and not break some of the principles of MVVM and definitions of Prism in order to do so.
I'm just 3 weeks into Prism and still learning but this is the biggest issue I'm running into.
Any thoughts?
You should be using the Event Aggregator for these types of communication scenarios. Essentially, you want a module to provide functionality but also expose events that can be invoked from other modules. You can also register a service in the Unity container. For example:
public interface ICustomerOrderInvoker
{
void DisplayCustomerOrdersInRegion(string customerId, string regionName);
}
These techniques are somewhat orthogonal to MVVM. Your event handler can create a view/viewmodel pair and insert them into a region. Or your event handler can create a UserControl with all functionality implemented in code behind and adds it to a region. The beauty of the composite UI is that your modules can use MVVM and another team's modules can use straight forward user controls or MVP or MVC or anything really; the point is that all the modules are composed into one application regardless of how they are implemented because they use the patterns established in Prism like regions, events, etc.
In your particular case:
You have these modules laid out and realize that you need to be able to show Orders for customer or sales people which are obviously employees.
Your Order module will certainly be aware of the concept of a customer id since the Order entity is associated with a customer. The Order module should expose an CompositePresentationEvent that displays a view that has all the orders for a particular customer id.
The point of Prism is to create logically separate and loosely coupled pieces of functionality. This does not mean that the modules do not communicate with each other, but rather that the communication happens in a limited and loosely coupled manner. You can certainly write LOB applications using this pattern and MVVM; many of us have been for years now. :)
Im working on a similar problem (and am new to Prism too), as yet don't have a solution. I think when using Prism its tempting to use the framework as the reference implementation intends, but it doesn't need to be so.
Prism should (when used correctly) facilitate software development, not hinder it. So don't get too stuck in the idea that any implementation must meet strict decoupled refactorised super patternised standards!
What I am doing/intending to do is create a MainModule, which has in it much of my core functionality, including a MainView/MainViewModel user control. The Shell then has one region "Main" and on MainModule load the MainView is injected into it as per standard prism usage.
I'm using a Docking Manager from Telerik (compatible with Silverlight and WPF) on the MainView and have implemented a class IDockingManager / DockingManager class in Infrastructure which is registered with Unity as a singleton (ContainerControlledLifetimeManager) in the bootstrapper.
Anywhere in my app I can get the IDockingManager instance and inject a view by calling IDockingManager.DockView(IView view, DockingParameters args). The DockingParameters can contain information such as where to dock (Left, right, top, bottom, tabbed document) and also the parent container to dock in.
This is the part I've not got to yet - I can dock left/right/top/bottom on the main view but I want to implement an attached property or something on my child views registering them as a DockSite when docked. So for instance I could dock a Treeview on the left and dock underneath that a listview by using the Treeview name as parent DockSite and DockBottom as the side.
Hope that makes sense, I've rambled without really explaining too well. Basically what Im saying is Im not using regions at all (except to inject the MainView) in this application and have created a class to handle view injection into dockable containers. It's not strictly Prism but Prism is there to make my life easier, not the other way around ;)
I would like to use Ninject in my WinForms application. I cannot figure out how to use it for my user controls. Sometimes they rely on the services I want to configure through the DI framework. These controls need to be manageable through the designer (thus need default constructors).
So, is there a way to inject dependencies into properties of this user control? Since the designer needs to be able to construct it, kernel.Get<TestClass> won't work here. Is there a method or some code that will let me "fill-in" the dependencies in the Form_OnLoad() method?
I can also think of other examples where I would want to Inject into the properties of an already existing object, but th WinForms user control is the easiest to explain.
I think you need to invert your thinking. In Model View Controller, the View has only one responsibility: to display data.
How that data gets there is the Controller's responsibility, and how the data is represented in memory is determined by the Model.
Although there are no specific MVC frameworks for Windows Forms, it's possible to make crude ones manually, or you could go have a look at the (now retired) Composite Application Block to get an idea about how this can be done (although the CAB is perhaps too complicated for most people's tastes). There are more elegant options available today, but they involve WPF.
In any case, instead of injecting your dependencies into your Views, inject them into Controllers, and have the Controllers instantiate and correctly populate the Views (your Controls).
In this way, you can keep your Controls free of DI concerns, as they should be.
I think the question is what DI tool can you use to get dependency injection to work with windows forms. Everyone does the MVC example because it's easy to implement(the same example if floating around the we as if it were new and original). If you have an answer for doing it using winforms or even WPF - that would be helpful.
This answer here basically says - in any case, I don't know so inject them into controllers and populate the views - really? Back to the MVC? Again - winforms.