We Keep Coding

cannot reference WPF controls in code-behind in a different page

I made a project where it was one page only, then after I made everything decided to go back in and make a second page, which was a huge mistake because now I have 50 compiler errors. In my new page's code behind, I cannot access any control by name and the page cannot access any event handlers in the code-behind. Here is an example:
Autoclicker.xaml
<Page x:Class="_1337clicker.Pages.Autoclicker"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:_1337clicker.Pages"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800"
Title="Autoclicker">
<Grid>
<Button Name="hi"/>
</Grid>
</Page>
Autoclicker.xaml.cs
using System.Windows;
using System.Windows.Controls;
namespace _1337clicker
{
public partial class Autoclicker : Page
{
public Autoclicker()
{
hi.Content = "hello world"; //The name "hi" does not
//exist in the current context
}
}
}

I think you just messed up classname/namespace.
Check in XAML:
x:Class="_1337clicker.Pages.Autoclicker"
This will generate all the variables related to controls in a class called Autoclicker in a namespace of _1337clicker.Pages
but then, your code-behind class is:
namespace _1337clicker // <---- DIFFERENT NAMESPACE
{
public partial class Autoclicker : Page
You ended up with two 'Autoclicker' classes, one generated from XAML, other writen by you. Correct the namespaces and class names so they are identical, and try again. Generated code will end up in the same class as codebehind, and probably all such errors will go away.
EDIT: also what Joe noticed, it should be x:Name. Just 'Name' will let you find the control with tree walking and/or find-by-name tools, but probably won't generate a variable for code-behind.

Is it good practice to have Pages that inherit from a custom class which itself inherits from Page?

The funny thing is that it worked. The compiler had no issues with the code, although it is something that I've never seen (maybe because I'm a novice). I would like to use the newly inherited base Page/class as a place to store commonly used code so that I don't have to duplicate anything. Take a look here:
public sealed partial class HumanPage : SpeciesBasePage;
public sealed partial class AnimalPage : SpeciesBasePage;
public class SpeciesBasePage : Page;
Obviously, it works because SpeciesBasePage implements the Page class. So you will also see that the related XAML page will have a different base class as its opening tag:
<local:SpeciesBasePage
x:Class="PageInheritanceProject.HumanPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
...>
<Grid>
<TextBlock Text="Hello, world!" />
</Grid>
</local:SpeciesBasePage>
Is it okay to do this? Thanks!

That's a fairly standard inheritance chain. In c# terms.
Two things to consider.
1)
Usage of Pages at all is the thing many commercial teams would question.
Many teams do not use pages at all and instead use usercontrols ( hosted in contentcontrols ).
2)
Inheriting from pages. You can't inherit xaml so why are you inheriting a UI control which is likely a container?

How to add multiple class file in one XAML file in WPF

I am designing a UI Library and I want to add two C# file to a XAML file so that in one file I can define only event Handler to be used in that Xaml file and in another file i can define some other UI related Style for controls. And i want my xaml file to have access to my both C# file class directly.
I am doing something like this using x:Class:
For example:
I want to add a MainWindow.cs file to my XAML file:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="TemplateLibrary.MainWindow">
But unfortunately XAML supports for only one class to get added to my XAML. Is there some way to add multiple C# file to a XAML file.

I think in your case you need to look in the direction of MVVM, because the further complication of the project will cause some difficulties. You can create multiple ViewModel's for a one View. In the role of View may suit:
UserControl
DataTemplate
In the case of UserControl this class can be partial, which will complement the other class. In the case of DataTemplate can dynamically change the content depending on View type.
In addition, all styles of Control's must be contained in ResourceDictionary and merged into the App.xaml file.

It seems that the MainWindow code behind is already a partial class file, and therefore we could choose to place some members into additional cs files using the same partial class in the same namespace.
namespace TemplateLibrary
{
public partial class MainWindow : Window
{
...
The same applies when making a UserControl.

More basic is "How to bind an XAML visual object to code". Ranny Meier's suggestion on declaring my class on it's page as a 'partial class' coupled with (can't find him again) suggestion of using a redirection on the mainwindow page actually works fine - all in the same name space of course.
xaml
<Button x:Name="Pnl_Btn_EditPaste" Click="Do_Btn_EditPaste_Click" VerticalAlignment="Top" Padding="2" Margin="-67,18,0,0" ScrollViewer.VerticalScrollBarVisibility="Disabled" Width="36" Height="30" RenderTransformOrigin="1.976,-0.568">
<Button.OpacityMask>
<ImageBrush ImageSource="pack://siteoforigin:,,,/Resources/BnFace_paste.png"/>
</Button.OpacityMask>
<Button.Background>
<ImageBrush ImageSource="pack://siteoforigin:,,,/Resources/BnFace_paste.png"/>
</Button.Background>
</Button>
It's the "Click=" portion, or binding, on the Button opening statement we're interested in . . .
mainwindow c#
namespace WpfAppFoolAround
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
// -- Edit Controls ---------------------------------------------------------
private void Do_Btn_EditPaste_Click(object sender, RoutedEventArgs e)
{
ContextControls.Btn_EditPaste(sender, e);
}
}
}
The shim on mainwindow to redirect us to the class method . . .
the class on a different page
namespace WpfAppFoolAround
{
public partial class ContextControls
{
// -- Edit Controls ---------------------------------------------------
internal static void Btn_EditPaste(object sender, RoutedEventArgs e)
{
Console.WriteLine("PASTE Editing Button Clicked.");
}
}
}
And the actual method located in the class on the odd project page we added.

WPF Combobox deriving from derived doesn't work

HOPEFULLY, someone strong in WPF knows what's going on... The scenario I've sampled below is also applicable to others too, like textbox, command buttons, etc...
I'm playing with creating custom user controls... Ex: working with a simple Combobox. In one project class library LibA I've created some samples derived from... ex: TextBox, ComboBox, Window, etc. A second library LibB I'm creating another class derived from ex: Combobox in LibA... Otherwise, no problem.... done similar thing in C# WinForms with no problems.
Now, the problem, I drag the control (from LibB) onto the first "Window" (native so no derivation issues) of the app, save and run. The derived library doesn't even hit its constructor which I just put a simple command just test it was getting created properly worked or not, but its not... In the XAML of the form, it is properly referencing both namespace projects, so I know that appears correct.
So, I then created a derived combobox in the same original LibA, put that on the form, and IT properly went into the constructor.
Here's a snippet of what I have going on.
namespace LibA
{
public class MyCombo1 : ComboBox
{
public MyCombo1()
{ ToolTip = "this is my base declaration"; }
}
public class MyCombo1b : MyCombo1
{
public MyCombo1b() : base()
{ ToolTip = "this constructor IS reached"; }
}
}
In a separate project (library),
using FirstLibraryThatHas_MyCombo1
namespace LibB
{
public class OtherLibCombobox : MyCombo1
{
public OtherLibCombobox() : base()
{ ToolTip = "this version is NOT being recognized in the window"; }
}
}
So, neither of these are visually designed, they are all in code only... In addition, I've done it with the TextBox control too, same results... It doesn't stop in the debugger... Any ideas?
Although I've changed actual names from sample, here's a brand new window, one with original class declaration AND one with the DERIVED version.. Here's a full XAML test window
<Window x:Class="MyProject.TestWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="TestWindow" Height="300" Width="300"
xmlns:my="clr-namespace:WPFGUI;assembly=WPFGUI"
xmlns:my1="clr-namespace:DerivedControls;assembly=DerivedControls">
<Grid>
<my:MyComboBoxClass
Name="MyComboBoxInWindow"
HorizontalAlignment="Left"
Height="23"
Width="120" />
<my1:cboDerivedComboClass
Name="cboDerivedComboInWindow"
Height="23"
HorizontalAlignment="Left"
Width="120" />
</Grid>
</Window>

Isn't this making a circular reference?
You call MyDerivedControl that is in another assembly, and DerivedControl needs the primary assembly
because it inherits a type you defined there.
And then, you try to display it in a window from the primary assembly?
Try to clean and rebuild your project.

I've tried and failed to reproduce the problem. I think you have a different problem, though. If you use the xaml above - the number two combobox will completely cover the first - thus you will not be able to get the tooltip...
Also, check that all assemblies target the same framework version.

Inheritance with Silverlight User Control Partial Classes

I am trying to allow several classes to inherit a more general Silverlight user control to avoid redundancy in my code. The classes inherit the extended control, which then inherits the User Control class. The issue I have been running into is that the ExtendedControlExtension.g.cs file regenerates every time I compile, with the incorrect inheritance (it inherits User Control not my Extended Control).
Note that I have been inheriting the Extended Control in the .cs and g.cs files, but continuing to use the User Control tag in the .aspx file as this causes the error
Error 29 The tag 'ExtendedControl' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation'.
Is there a way to fix this?
Thanks!

You cannot change the .g.cs file, in fact is says so right in the file. Also, it's unfortunate to use the term "custom control" as this means something specific and not what you are trying to do. But, the good news is that what you are trying to do is possible.
Derive from UserControl:
public class FancyUserControl : UserControl
{
// Your added common functionality.
}
and then add a new UserControl to your project using the normal mechanism, let's say UserControl1. Then edit the UserControl.xaml files as follows:
<local:FancyUserControl x:Class="SilverlightApplication1.UserControl1"
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:SilverlightApplication1"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
</Grid>
</local:FancyUserControl>
paying special attention to the three lines with local in them, adjusting to your application. Then edit the UserControl1.xaml.cs file as follows:
public partial class UserControl1 : FancyUserControl
{
public UserControl1()
{
InitializeComponent();
}
}
and Visual Studio won't be quite happy yet but finally rebuild your project and all will be well.
The class UserControl1 is now derived from FancyUserControl instead of UserControl and you can begin adding your common functionality. To add more controls you will need to manually edit the XAML and code-behind once after initially adding each new control to the project.