I'm working on a WinForm application using ninject for dependency injection. My first problem was that the form being instantiated had a parameter (for DI). I added a parameterless constructor thinking this would help. The problem now is that the code inside the constructor with the parameter gets skipped. Here what it looks like:
On my main form:
private void mnuSettings_Click(object sender, System.EventArgs e)
{
frmSettings objForm = new frmSettings();
objForm.Owner=this;
objForm.Show();
}
In the frmSettings form:
private readonly IApplicationPropertiesInterface _applicationProperties;
public frmSettings()
{
InitializeComponent();
}
public frmSettings(IApplicationPropertiesInterface applicationProperties) : this()
{
_applicationProperties = applicationProperties;
}
When I call _applicationProperties.GetExtractFileSaveLocationDirectory() it blows up because the code to set _applicationProperties was never called.
Im wondering if I have structured this incorrectly, and what the best way to achieve this is. My goal is to call the parameterless constructor, but also set _applicationProperties.
Any assistance would be most grateful.
I'm guessing you might be expecting that having Ninject in the building will mena that new will work differently to normal. It doesn't - you need to be doing a kernel.Resolve<Something> for the DI to kick in. Note that most of these pitfalls are covered in detail on the wiki
Can you edit your answer to include details of what you're doing outside of this form please?
In the meantime, here are some previous questions that overlap significantly:-
What is the best practice for WinForms dialogs with ninject?
How to use Ninject in a Windows Forms application?
Related
I am very new to WPF and MVVM Pattern. I even have no experience on windows.
I have Created Simple login window
_ Login.xaml, LoginViewModel.cs
_ Dashboard.xaml, DashboardViewModel.cs
After Login Successfully - ( In Login time we will select Language also )
I am Displaying Username & Selected Language in Dashboard window
I wrote code like this:
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
try
{
var login = new Login();
var loginVM = new LoginViewModel();
Dashboard main = null;
loginVM.LoginCompleted += (sender, args) =>
{
DashboardViewModel dvModel = new DashboardViewModel(loginVM);
main = new Dashboard();
main.DataContext = dvModel;
main.ShowDialog();
login.Hide();
};
login.DataContext = loginVM;
login.ShowDialog();
}
catch (Exception ex)
{
throw ex;
}
}
In Dashboard Window it is displaying username and Language successfully.
But my problem is those two (Username & Language) properties I want to use in dashboard codebehind for update the layout based on language & other xaml files or other viewmodels . How to do that one ?
Technically I want to use Loginviewmodel object in all viewmodels.
Based on Selected Language I want to update Layout.
Note: Is this login approach good ? Is there any alternative for Globalization in MVVM pattern ?
Using a ViewModel for login is perfectly valid. I would perhaps create a token in your loginVM to pass around the system, depending on your needs. That token should be passed into the constructors of your other viewmodels from your main view model (DashboardViewModel?). This can be resolved using any decent IoC container.
For globalization/localization, I would use resources (in satellite assemblies). We've experimented with various things, and found that we didn't like the WPF UUIDs added everywhere when using LocBaml. And storing translation is a database quickly became a performance hog (even when loading in bulk). This does require you to find your labels etc. to a resource manager, but in my opinion, it is worth it.
Take a look at this article, for a nice extension, that enables you to simply write:
<TextBlock Text="{Resx MyText}"/>
And it will be translated using resource files.
An alterative approach is to simply store the Username and Language is a static property. I know most people don't like globals, but something like this is in nature very global, and you will still be able to inject it in if you so desire. The downside of this approach is that your unit tests would have to setup this static variable first.
EDIT An example of the static approach:
public static class RuntimeInfo {
public static string UserName { get; set; }
public static CultureInfo UserCulture { get; set; }
}
In your loginVM, simply store the necessary values in a static class. This can be accessed anywhere needed. This is not as 'correct' as the previous approach, but it can be more pragmatic than having to pass the username into every single ViewModel in your application.
I still recommend injection through an IoC container though.
I'm seeing, more and more code like the code below in an MVVM application (WPF and Prism). Controllers have the following code fragments:
public class DispenseOptionController : IDispenseOptionController
{
protected readonly Func<IPharmacyCdmServiceSimpleClient> CdmClient;
protected readonly Func<IPatientServiceSimpleClient> PatientClient;
public DispenseOptionController(Func<IPharmacyCdmServiceSimpleClient> cdmClient, Func<IPatientServiceSimpleClient> patientClient)
{
CdmClient = cdmClient;
PatientClient = patientClient;
}...
I'm trying to understand the role that Func<> plays here. It seems that this delegate is used as parameters to the constructor. Can someone explain to me why anyone would use Func<> in this particular case? And can Func<> be replaced with anything else?
A Func<> is nothing but the Encapsulation of a method that one or more parameter and returns a value of the type specified by the TResult parameter.
You could see some use cases here
I have a project in WPF with a lot of UserControls, some user controls uses Kinect KinectColorViewer.xaml
I want to handle the sensor discovering and setup (conect, disconect, etc) in main window and serve it to my UserControls, how is the best way to do it?
Here is the project that explains my question.
If you prefer, here are the github link.
From your example code,
Assuming you want to maintain as much of the already available code from Microsoft, you will want to set up a reference to the KinectSensorManager on initializing your application. My constructor normally looks something like this:
private readonly KinectSensorChooser sensorChooser = new KinectSensorChooser();
public KinectSensorManager KinectSensorManager { get; private set; }
public MainViewModel()
{
// initialize the Kinect sensor manager
KinectSensorManager = new KinectSensorManager();
KinectSensorManager.KinectSensorChanged += this.KinectSensorChanged;
// locate an available sensor
sensorChooser.Start();
// bind chooser's sensor value to the local sensor manager
var kinectSensorBinding = new Binding("Kinect") { Source = this.sensorChooser };
BindingOperations.SetBinding(this.KinectSensorManager, KinectSensorManager.KinectSensorProperty, kinectSensorBinding);
}
The KinectSensorManager is just a helper class. You can rewrite code to easily avoid using it, but it doesn't do anything bad (does a lot of nice stuff for you) so I've just keep using it. Also, since I'm assuming you want to re-use as much code as possible, we want to maintain its usage.
For your control, you can extend KinectControl which will set up a bunch of helpful items for you. So...
public partial class KinectUserControl : KinectControl
{
...
}
This will give your control access to a lot of override-able functions that listen in to various events (like KinectSensorChanged). Check our the KinectColorViewer code and you can see how it overrides this function, which allows it to automatically start displaying new data if you swap Kinects.
When declaring your control in the XAML you can now add a reference to the KinectSensorManager:
<my:KinectUserControl KinectSensorManager="{Binding KinectSensorManager}" />
Because your control now has a KinectSensorManager property, it should pass through to your KinectColorViewer control as well.
I'm using WPF, MVVM and Entity Framework in my current project.
To keep things simple, let's say I have a viewmodel for CRUD operations towards a list of materials (Solid woods).
My ViewModel's EF context (WTContext) is initialized through property injection, for instance:
SolidWoods_VM newView = new SolidWoods_VM();
newView.Context = new WTContext(SettingsManager.Instance.GetConnectionString());
This way I'm able to test this ViewModel:
SolidWoods_VM swVM = new SolidWoods_VM();
swVM.Context = new FakeWTContext();
Imagine that during a insert operation something goes wrong and the WTContext.SaveChanges() fails.
What is the best way to refresh the ViewModels context?
Create a new bool property in the viewmodel named ForTestingPurposes, and when the SaveChanges method fails:
try
{
Context.SaveChanges();
}
catch
{
if (!ForTestingPurposes)
{
Context = new WTContext(SettingsManager.Instance.GetConnectionString());
}
}
Send a message to the mainviewmodel for context reloading (through mediator pattern):
Mediator.Instance.NotifyColleagues<SolidWoods_VM>(MediatorMessages.NeedToUpdateMyContext, this);
(Yet, this way I'd still need the bool property)
3.A more elegant solution, without aditional properties, provided for you guys :)
Why not abstract the methods/properties you need on your data context onto an interface and then have an implementation of that that handles the exception.
//WARNING: written in SO window
public interface IDataSource
{
void SaveChanges();
//... and anything else you need ...
}
public class RealDataSource : IDataSource
{
private WTContext _context;
public void SaveChanges()
{
try { _context.SaveChanges(); }
catch
{
_context = new WTContext(/*...*/);
}
}
}
This way you can still implement a fake/mock data source but your view model class doesn't need to know anything about how the data is actually retrieved.
My opinion is that your best bet would be the message.
You need a way to indicate that the save went wrong, and it might not serve all consumers of the class to have the context regenerated. If you're binding to your VM in there, for example, resetting the context might have other UI consequences.
I am using an attached Behaviours to add drag and drop functionality to my code.
So far, everything is working fine, but my problem is when I want to test my behaviour classes.
For example, one of the behaviour classes would be something like the following:
public class DroppableContainerBehavior: Behavior<FrameworkElement>
{
protected override void OnAttached()
{
base.OnAttached();
AssociatedObject.AllowDrop = true;
AssociatedObject.Drop += new DragEventHandler(AssociatedObject_Drop);
AssociatedObject.DragOver += new DragEventHandler(AssociatedObject_DragOver);
AssociatedObject.DragLeave += new DragEventHandler(AssociatedObject_DragLeave);
}
private void AssociatedObject_Drop(object sender, DragEventArgs e)
{
...
}
}
My problem now is when I want to create a unit test for the AssociatedObject_Drop method, i would need to create a DragEventArgs object, but this class is sealed.
I got the impression that I am doing something wrong..
My question is, should i be testing my behaviour classes? Behaviours are related with UI, and usually it's not worth it to test UI. Am i right?
Maybe I have to change my behaviours code to make it more testable? any ideas?
Thanks for your help!
I would refactor the code and move out any business logic from AssociatedObject_Drop into its own function(s) and then write my unit tests for those functions.
you can create an object even its class is sealed.
you can test the raise Drop() event in your unit test
you also can test the AssociatedObject_Drop() method logic by extracting its code to other function and write the unit test for this function.