We Keep Coding

Generic Argument Constraint Violation?

I have declared a base dialog window class that types the datacontext to ensure that the attached viewmodel has the appropriate return type. When I try to use it though I get a generic arguments error:
GenericArguments[1],
'Mocks.MidSoft_Hospitality_ViewModels_Dialogs_ReceiveItemViewModel_32_569724456',
on
'Mocks.MidSoft_Hospitality_Views_Dialogs_BaseDialogWindow`2_32_569724456[TResult,TViewModel]'
violates the constraint of type 'TViewModel'.
I can't see why this would be happening
The base dialog window declaration:
public class BaseDialogWindow<TResult, TViewModel> : DialogWindowBase<TResult> where TViewModel: ViewModels.Dialogs.DialogBaseViewModel<TResult>
{
public BaseDialogWindow() : base()
{
}
new public TViewModel DataContext
{
get => this.GetValue(DataContextProperty) as TViewModel;
set => this.SetValue(DataContextProperty, value);
}
}
DialogWindowBase:
public class DialogWindowBase<TResult> : Window, IDialog<TResult>
{
public DialogWindowBase()
{
//Formatting code here
}
public Result Result { get; set; } = Result.None;
public TResult ReturnData { get; set; }
}
The viewModel:
public class ReceiveItemViewModel : ViewModels.Dialogs.DialogBaseViewModel<ReceiveItemResult>
{
//View Model Code here
}
and the xaml:
<local:BaseDialogWindow x:Class="MidSoft.Hospitality.Views.Dialogs.ReceiveItemDialog"
x:TypeArguments="local:ReceiveItemResult, vm:ReceiveItemViewModel"
xmlns:vm="clr-namespace:MidSoft.Hospitality.ViewModels.Dialogs"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MidSoft.Hospitality.Views.Dialogs"
mc:Ignorable="d"
d:DataContext="{d:DesignInstance vm:ReceiveItemViewModel, IsDesignTimeCreatable=False}"
x:Name="ReceiveStockItemDialog"
Height="450" Width="800">
<Grid>
</Grid>
</local:BaseDialogWindow>
Code for the dialog:
public partial class ReceiveItemDialog
{
public ReceiveItemDialog()
{
InitializeComponent();
}
}
The error that I referenced above is the only compiler error that I am getting. I would appreciate any insight into this error.
Update: I have now noticed that the application is compiling and running without any exceptions being thrown but the error is still there and the xaml designer is showing it as invalid markup

IsDesignTimeCreatable=False will force the designer to ignore the specified DesignInstance type and create a substitute type using reflection. In this case the designer failed to recognize the generic type as it is a complex type rather than a primitive type and therefore failed to create a proper mock instance with a proper generic parameter TViewModel.
To solve this, you could set the IsDesignTimeCreatable property to True and implement a default constructor on ReceiveItemViewModel. If a default constructor is not possible, introduce a wrapper type just for the design time DesignInstance and spend it a a default constructor that initializes the base type ReceiveItemViewModel properly.

c# WPF 'The name xxx does not exist in the namespace - what am i missing?

I am trying to learn WPF, and specifically, understand data-binding. I have started to run through some examples online. I cannot get this one to work. I have created a Simple Person object as follows and it is in the correct namespace.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace SimpleDataBinding
{
public class Person
{
private string name;
public Person()
{
}
public Person(string value)
{
this.name = value;
}
public string PersonName
{
get { return name; }
set { name = value; }
}
}
}
I have created an object of this type.
namespace SimpleDataBinding
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
Person Person = new Person();
public MainWindow()
{
InitializeComponent();
this.DataContext = this;
}
}
}
and the XAML is as follows - the last line shows the line that it fails on.
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:src="clr-namespace:SimpleDataBinding"
SizeToContent="WidthAndHeight"
Title="Simple Data Binding Sample">
<Window.Resources>
<src:Person x:Key="myDataSource" PersonName="Joe"/>
The error from the build is.
Severity Code Description Project File Line Suppression State
Error The name "Person" does not exist in the namespace "clr-namespace:SimpleDataBinding". SimpleDataBinding ...\repos\SimpleDataBinding\SimpleDataBinding\MainWindow.xaml
But, Person does exist, and is in the shared namespace. Looking around here at similar issues all i get are recommendations to rebuild, or clean and rebuild - none of which seem to help anyone (or me).
As i'm new to this, it's likely, i just don't understand something and it's super-frustrating as i should surely be able to get this to work!
I've pushed the project to github here if it helps anyone...

You appear to be missing the x:Class directive on your window definition. Update your window element in the XAML:
<Window
x:Class="SimpleDataBinding.MainWindow"
....

C# web browser constructor

I am trying to add a web browser to an existing C# application, but, having not used C# in about 6 years, I am quite unfamiliar with how it works.
I am trying to add the browser to a partial class (again, something I am not familiar with) using the following code:
public partial class WebBrowser : WebBrowserBase{
public WebBrowser(){
...
}
...
}
However, I am getting a compile error on the constructor that says:
'WebBrowserBase' does not contain a constructor that takes 0 arguments
I Google'd this, and came across the following question on SO: C# Error: Parent does not contain a constructor that takes 0 arguments. I tried doing what was suggested in the answer to this, and changed my code to:
public partial class WebBrowser : WebBrowserBase{
public WebBrowser(int i) : base(i){
...
}
...
}
However, I then get a compile error that says:
'WebBrowserBase' does not contain a constructor that takes 1 arguments
So I'm guessing that this issue isn't to do with the number of arguments in the constructor... Can anyone explain what I'm doing wrong here?

If you have a look at WebBrowserBase Class it states that:
"This API supports the product infrastructure and is not intended to be used directly from your code."
And it seems that it doesn't have any public constructor - so you can't inherit from it. But if you don't want to create your own WebBrowser control (alter some of it's functionality), you should just use the default System.Windows.Forms.WebBrowser in a XAML View:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow"
Width="525"
Height="350">
<WebBrowser HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />
</Window>

In Inheritance,
If Derived class contains its own constructor which not defined in Base class then this error Occurs
For Example:
class FirstClass
{
public FirstClass(string s) { Console.WriteLine(s); }
}
class SecondClass : FirstClass
{
public SecondClass()
{
Console.WriteLine("second class");
}
}
Output: Error:-'myconsole.FirstClass' does not contain a constructor that takes 0 arguments
To Run without Error:
class FirstClass
{
public FirstClass()
{
Console.WriteLine("second class");
}
public FirstClass(string s) { Console.WriteLine(s); }
}
class SecondClass : FirstClass
{
public SecondClass()
{
Console.WriteLine("second class");
}
}

Namespace for my project

What namespace i should to add for my project?
At this moment i get this error "Partial declarations of WPFApplication3.method must not specify different base classes"
Below is my code:
Code Method.xaml:
<Window x:Class="WpfApplication3.method"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="method" Height="300" Width="300">
//some code
</Window>
Code Method.cs:
namespace WpfApplication3
{
/// <summary>
/// Interaction logic for method.xaml
/// </summary>
public partial class method : MonoBehaviour
{
public method()
{
InitializeComponent();
}
}
}

Change your Base class in .cs file to Window
namespace WpfApplication3
{
/// <summary>
/// Interaction logic for method.xaml
/// </summary>
public partial class method : Window
{
public method()
{
InitializeComponent();
}
}
}

If you want to have a base class of MonoBehavior in your code-behind, you'll need to change your XAML accordingly, to specify the same base class.
Change this:
<Window x:Class="WpfApplication3.method" ... >
To this:
<Window x:Class="WpfApplication3.MonoBehavior" ... >

How can a WPF UserControl inherit a WPF UserControl?

The following WPF UserControl called DataTypeWholeNumber which works.
Now I want to make a UserControl called DataTypeDateTime and DataTypeEmail, etc.
Many of the Dependency Properties will be shared by all these controls and therefore I want to put their common methods into a BaseDataType and have each of these UserControls inherit from this base type.
However, when I do that, I get the error: Partial Declaration may not have different base classes.
So how can I implement inheritance with UserControls so shared functionality is all in the base class?
using System.Windows;
using System.Windows.Controls;
namespace TestDependencyProperty827.DataTypes
{
public partial class DataTypeWholeNumber : BaseDataType
{
public DataTypeWholeNumber()
{
InitializeComponent();
DataContext = this;
//defaults
TheWidth = 200;
}
public string TheLabel
{
get
{
return (string)GetValue(TheLabelProperty);
}
set
{
SetValue(TheLabelProperty, value);
}
}
public static readonly DependencyProperty TheLabelProperty =
DependencyProperty.Register("TheLabel", typeof(string), typeof(BaseDataType),
new FrameworkPropertyMetadata());
public string TheContent
{
get
{
return (string)GetValue(TheContentProperty);
}
set
{
SetValue(TheContentProperty, value);
}
}
public static readonly DependencyProperty TheContentProperty =
DependencyProperty.Register("TheContent", typeof(string), typeof(BaseDataType),
new FrameworkPropertyMetadata());
public int TheWidth
{
get
{
return (int)GetValue(TheWidthProperty);
}
set
{
SetValue(TheWidthProperty, value);
}
}
public static readonly DependencyProperty TheWidthProperty =
DependencyProperty.Register("TheWidth", typeof(int), typeof(DataTypeWholeNumber),
new FrameworkPropertyMetadata());
}
}

Ensure that you have changed the first tag in the xaml to also inherit from your new basetype
So
<UserControl x:Class="TestDependencyProperty827.DataTypes.DataTypeWholeNumber"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:System;assembly=mscorlib"
>
becomes
<myTypes:BaseDataType x:Class="TestDependencyProperty827.DataTypes.DataTypeWholeNumber"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:s="clr-namespace:System;assembly=mscorlib"
xmlns:myTypes="clr-namespace:TestDependencyProperty827.DataTypes"
>
So, to summarise the complete answer including the extra details from the comments below:
The base class should not include a xaml file. Define it in a single (non-partial) cs file and define it to inherit directly from Usercontrol.
Ensure that the subclass inherits from the base class both in the cs code-behind file and in the first tag of the xaml (as shown above).

public partial class MooringConfigurator : MooringLineConfigurator
{
public MooringConfigurator()
{
InitializeComponent();
}
}
<dst:MooringLineConfigurator x:Class="Wave.Dashboards.Instruments.ConfiguratorViews.DST.MooringConfigurator"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:dst="clr-namespace:Wave.Dashboards.Instruments.ConfiguratorViews.DST"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
</Grid>
</dst:MooringLineConfigurator>

I found the answer in this article: http://www.paulstovell.com/xmlnsdefinition
Basically what is says is that you should define an XML namespace in the AssemlyInfo.cs file, which can the be used in the XAML. It worked for me, however I placed the base user control class in a separate DLL...

There is partial class definition created by designer, you can open it easy way via InitializeComponent() method definition.
Then just change partial class iheritence from UserControl to BaseDataType (or any you specified in class definition).
After that you will have warning that InitializeComponent() method is hidden in child class.
Therefore you can make a CustomControl as base clas instead of UserControl to avoid partial definition in base class (as described in one comment).

I ran into the same issue but needed to have the control inherit from an abstract class, which is not supported by the designer. What solved my problem is making the usercontrol inherit from both a standard class (that inherits UserControl) and an interface. This way the designer is working.
//the xaml
<local:EcranFiche x:Class="VLEva.SIFEval.Ecrans.UC_BatimentAgricole"
xmlns:local="clr-namespace:VLEva.SIFEval.Ecrans"
...>
...
</local:EcranFiche>
// the usercontrol code behind
public partial class UC_BatimentAgricole : EcranFiche, IEcranFiche
{
...
}
// the interface
public interface IEcranFiche
{
...
}
// base class containing common implemented methods
public class EcranFiche : UserControl
{
... (ex: common interface implementation)
}