I'm currently working on a brownfield application, it's written with winforms,
as a preparation to use WPF in a later version, out team plans to at least use the
MVVM/Presentation model, and bind it against winforms...
I've explored the subject, including the posts in this site (which i love very much),
when boiled down, the main advantage of wpf are :
binding controls to properties in xaml.
binding commands to command objects in the viewmodel.
the first feature is easy to implement (in code), or with a generic control binder, which binds all the controls in the form.
the second feature is a little harder to implement, but if you inherit from all your controls and add a command property (which is triggered by an internal event such as click), which is binded to a command instance in the ViewModel.
The challenges I'm currently aware of are :
implementing a commandmanager, (which will trigger the CanInvoke method of the commands as necessery.
winforms only supports one level of databinding : datasource, datamember, wpf is much more flexible.
am i missing any other major features that winforms lacks in comparison with wpf, when attempting to implement this design pattern?
i sure many of you will recommend some sort of MVP pattern, but MVVM/Presentation model is the way to go for me, because I'll want future WPF support.
Thanks in advance,
Erik.
Please take a look at Update Controls .NET. It is an open-source library for Winforms, WPF, and Silverlight that keeps controls up to date as data changes. You can start using it now for Winforms, and then transition over to WPF without changing your Data Model or View Model code.
Unfortunately, it does not solve the Winforms command binding problem. Your button click events will not port from Winforms to WPF. But it does take care of the data binding problem.
You might find the WAF Windows Forms Adapter interesting. It shows how to apply the Model-View-ViewModel (MVVM) Pattern in a Windows Forms application. The Adapter implementation provides a solution for the missing Command support in Windows Forms.
Related
How do I use multiple windows in an WPF MVVM app?
I have a Main Window with a menu control that needs to open up new instances of the window each time the item it is selected. I need to be able to show windows next to each other, it is a requirement and not page or usercontrol navigation.
Does anyone have an example of doing this?
I've read it is not recommended UI design but it is the requirement I have to implement.
Actually I have this working by using the WindowManager from Caliburn.Micro which seems like an very excellent framework for this type of application. I did look into prism but it seems over complicated and Caliburn is very easy to understand which did meet the requirements. I looked into MVVM Light but the documentation is horrible and lacks examples and I don't have time to figure it out.
I'm familiar with WPF technology, specifically MVVM methodology. Recently I began to program in Winforms, and I was wondering- Does using data-binding in winforms (combined with INotiify...) is considered the best practice, or is it an overkill?
Some people say that data-binding is a real pain in the ass in winforms, is that right?
And just to make it clear: I'm not talking about full MVVM implementation in winforms- simply binding data to controls (text boxes and such, not buttons).
Data binding in Windows Forms works very differently than WPF - and is (IMO) a bit more of a pain. The main issues are there are more restrictions on the binding source, and there isn't a clean way to handle things like IValueConverter, so there is typically a lot of extra work involved in getting anything but very simply binding to work cleanly.
Details on how to use data binding in Windows Forms are described on MSDN in Windows Forms Data Binding.
I think I have a pretty good understanding of the MVVM design model, however I have a quarm with it in regards to WPF, Command bindings and how we are meant to use them.
To bind commands to the XAML directly we are meant to implement the ICommand interface within the ViewModel. Now, the ICommand interface is part of the PresentationCore.DLL, which, correct me if im wrong is part of WPF not the base .NET framework.
Isnt the whole point of the ViewModel and Model that it should be totally UI independant? For example, if I implement ICommand in my ViewModel and use it as a data context in order to bind commands from the XAML, isnt my ViewModel then dependant on the WPF frame work (in particular the PresentationCore.Dll).
What I mean is, if I was to go and try to use my Models and ViewModels in lets say a Windows Forms environment, I would have to reference the PresentationCore.DLL even though I shouldnt need it because im using Windows Forms not the WPF framework.
This seems a bit odd to me, am I missing something here? Is there another way I should be doing it to keep my Model and ViewModel totally UI and UI Framework independant, but still be able to utilise the Command binding in XAML?
Thanks in advance!
I also had this kind of problem but not in wpf but in POCO classes. What i did was I created two partial classes in two different assemblies. Like you create one partial class which is not presentationcore.dll dependent in your VM project and create its partial class in another assembly(say WPFVM) which implements ICommand stuff. Now for Winforms stuff add only VM project reference to View project and for WPF stuff add references of both VM and WPFVM to the View project. I hope this will help.
The point of MVVM is to have the view just be a view, and nothing more. Putting ICommands into the view model helps this as it pulls the code away from the view. Where you will run into problems is if you have to access something on the view that is not a dependency property, which means you can not bind to it.
In my opinion MVVM is very popular with the WPF, Silverlight because it naturally fits into it. The data binding concept in the XAML allows the Views & ViewModels to be bridged using a single property which is the DataContext. As no longer your logic is tied to controls, you get better testability, design-code separation and maintainability. You may be able to implement the MVVM pattern in other places also, but in WPF and Silverlight, it fits so easily due to its data and command binding support. I have read somewhere that, Don't take patterns religiously. They were made to make your life simpler rather than giving you more problems while following it. For Winforms i think there are better patterns, If you are focusing in reusing the business logic, move them out of your ViewModels to seperate classes something like serviceproviders or serviceagents and share them between your Winforms and WPF apps.
This has changed in .NET 4.5 compare
.NET Framework 4.5
.NET Framework 4
In many ways I think of using the MVC pattern in WinForms, but I'd like to know if it's possible to bind controls with objects using the ObservableCollection type? If it's purely for WPF, what other alternatives are out there?
To put it into perspective, we're building a system which has business logic that I'd like to control the UI with, instead of making customizations for each requirement or workflow on the UI itself. We have around a few hundred potential forms which I'd like to start designing with the pattern in mind.
We're also building web interfaces for most of the processes, but in reality they're just watered-down versions of the Forms. If I can use the same framework which I can just bind to on the web form that would be awesome.
Thanks
What ObservableCollection does is that it implements INotifyPropertyChange and each control in WPF has the possibility to listen for it's bound data to raise the event from INotifyPropertyChange. You can read more here about why you can't use ObservableCollection they way you want to in WinForms.
Another way is to use the Model-View-Presenter pattern:
This pattern can also be used in ASP.NET.
There's an MSDN Magazine Article on: "Better Web Forms with the MVP Pattern" that I think you should look into. And here is an introduction to how you use MVP-pattern in asp.net.
I am thinking about the design of a WPF or Silverlight application. I am planning to use MVC (or another such design pattern)
Witch ever of the design patterns I choose, I need to connect to view to the model (or presenter) – is databinding a good way of doing this?
(In the past with WinForms applications I have found that Databinding give lots of problem in the long run and does not fulfil its promise. It is the same with WPF and Siverlight?)
Yes, you should definitely definitely use data binding. While WinForms and ASP.NET were always a struggle to get anything data bound consistently and in a maintainable manner, Silverlight and WPF are built from the ground up for data binding pleasure.
Binding is two-way so you don't have to write tedious plumbing code to move data in and out of your model. Just implement INotifable and away you go.
Converters allow you to write code to handle the way things are bound if the defaults aren't working. Using converters (which are dead-simple to write) you can bind booleans to visibility settings, strings to images, integers to background colors, and so on. The sky's the limit.
Patterns such as MVVM are perfect for the rich data-binding support in WPF and Silverlight. MVVM lets you have the best of both worlds: loosely coupled code together with data binding.
Element binding lets you bind the property one element to the property of another element. Together with converters, this gives you impressive power to do things like bind the current position of a slider control to the selected index of a list control. Both ways.
Deep binding means you can bind to the property of a property of your model. Not that you always should, but you can.
Binding is almost magical in its dynamic-ness. As long as your model continues to support the same bound properties, binding will continue to work even if the static type of the model changes. Binding is also crazy flexible. You can bind to collections, interfaces, complex objects, (almost) anything you like.
DataContexts can be used to set up data-binding at a page, control, or container level. Children of the container then inherit the same data-context. This lets you bind once at the page level and then use binding paths for the rest of the page.
I recommend you take a look at the Model-View ViewModel (MVVM) pattern. Here is a very good video you should take a look at: Jason Dolinger on Model-View-ViewModel. Two-way data binding in WPF is very powerful.
be it WPF or Adobe Flex or Winforms , Databinding will always give issues when the application becomes complex. I would prefer to avoid data binding for easier debugging. But data binding runs all around WPF that we can't avoid. Doing data binding in XAML takes away control from the developer.
I think , if we keep the data binding in the code , its much easier to debug.
Imagine , MVVM without data binding , it will look messy. A design pattern that takes advantage of technology is good but a design that is totally dependent on a particular feature is a disaster.
Data binding in WPF goes far beyond what you could achieve in Winforms. It is intrinsic to the platform and prevalent throughout. I would argue you can't understand WPF without understanding its data binding system.
It's not without its pitfalls, to be sure. Broken bindings are often not as obvious as you may like, but improvements have been made to help you identify and flag these issues.