Problems with DataContext - wpf

xmlns:viewModel="clr-namespace:LoginViewModule.ViewModel"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300"
d:DataContext="{Binding Source={viewModel:LoginContentViewModel}}">
It is saying that:
LoginContentViewModel doesnt exists and invalid markup extension.
Can somebody please tell me what I'm doing wrong?

Try rebuilding first, it may just be that it can't see the ViewModel yet.
If that doesn't work you can do it like this, though this is not ignored by the xaml processor:
<Window.DataContext>
<viewModel:LoginContentViewModel />
</Window.DataContext>
Or if you are wishing for it to be ignored by the xaml processor this should work:
d:DataContext="{Binding viewModel:LoginContentViewModel}"
EDIT: Make sure your namespaces are correct, otherwise none of the above will have any effect.
Your folder structure does not necessarily mean that your namespaces are in that layout. You need to check the LoginContentViewModel.cs to make sure that the namespace there is LoginViewModule.ViewModel and not just LoginViewModule which would have occurred if you added your files to your root directory and then moved them into the folder

Related

IOException when referencing App.xaml's ResourceDictionary

I'm trying to reference App.xaml's ResourceDictionary from a separate WPF window. I want to use resources from there in different windows, and this seems like the recommended way to do it. Unfortunately, I don't seem to be able to effectively reference App.xaml from the other window. Here is my App.xaml:
<Application x:Class="View.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:ViewModel="clr-namespace:ViewModel;assembly=ViewModel"
xmlns:local="clr-namespace:View"
StartupUri="ClockView.xaml">
<Application.Resources>
<ResourceDictionary>
<local:PriorityToIconConverter x:Key="PriorityToIconConverter" />
</ResourceDictionary>
</Application.Resources>
Notes: I'm not using MainWindow, so I've replaced the startup URI with a form that always comes up. I noted that in some other answers, the location of MainWindow is sometimes the issue. In my case, I haven't seen any difference between using ClockView or MainWindow. Both ClockView and MainWindow exist in the root namespace, MainWindow is just never loaded. I also have more resources, but I've removed them for the sake of conciseness.
Here's a simplified example of the code where I'm trying to reference the ResrouceDictionary from App.xaml:
<local:AssistantWindow
x:Class="View.AutomatorView"
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:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
xmlns:properties="clr-namespace:View.Properties"
xmlns:local="clr-namespace:View"
mc:Ignorable="d"
Title="Tool"
x:Name="Tool"
Background="Transparent"
Height="600"
Width="450"
Topmost="{Binding Source={x:Static properties:Settings.Default}, Path=ToolAlwaysOnTop}"
MinHeight="515"
MinWidth="150">
<Window.Resources>
<ResourceDictionary Source="App.xaml" />
</Window.Resources>
Again, this is simplified to be concise. When I try to load this form, I get the exception:
System.Windows.Markup.XamlParseException: ''Set property 'System.Windows.ResourceDictionary.Source' threw an exception.' Line number '21' and line position '10'.'
Inner Exception
IOException: Cannot locate resource 'tool/app.xaml'.
The view for "Tool" is located in a folder that is also named "Tool." However, the xaml and code behind don't reference this namespace, I'm just using the folder to organize my classes. It looks like it's looking for App.xaml in the folder the view resides in. App.xaml resides in the root namespace (View). I've tried modifying the source in the xaml for Tool to:
- View.App.xaml
- View:App.xaml
- View/App.xaml
How can I get this reference to work, so I can share resources throughout my application? Thank you.
You can't load App.xaml like you're trying to do because it's not actually a ResourceDictionary. You can only specify ResourceDictionary files as the target of Source.
However, if you declare a resource in App.xaml, you can reference it anywhere without needing to load the file it's in. That's done for you automatically. Therefore, you can reference your converter at any time with {StaticResource PriorityToIconConverter}.
Note that if you moved it from the default starting location (the base project folder) you may have to update its location. Right click your project, then Properties. Navigate to the "Application" tab (should be the uppermost element on the left-hand sidebar) and look for the "Startup object" field. Set that to [ProjectName].[Namespace?].[Namespace?].App. When I tested it, mine worked without needing to manually change the location, but your setup may be different.

IntelliSense for Data Binding not working - followup

Having got IntelliSense for Data Binding working in a simple test application, thanks to the answer to my previously raised question, I'm now trying to apply what I've learnt to the actual application I'm working on. Again I'm encountering problems that I don't understand. A snippet of my code is below - I've had to change names to protect propriety information:
<Page x:Class="MyProject.Views.Pages.MyPage"
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"
mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="450"
xmlns:Converters="clr-namespace:MyProject.Converters"
xmlns:ViewModels="clr-namespace:MyProject.ViewModels"
Title="My View"
SnapsToDevicePixels="True" KeepAlive="True" TextOptions.TextFormattingMode="Display">
<Page.Resources>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
<Converters:NullToVisibilityConverter x:Key="NullToVisibilityConverter"/>
</Page.Resources>
<StackPanel d:DataContext="{d:DesignInstance ViewModels:MyViewModel}">
<!-- ... -->
</StackPanel>
</Page>
I'm getting an error message on the line <StackPanel d:DataContext="{d:DesignInstance ViewModels:MyViewModel}">:
The name "MyViewModel" does not exist in the namespace "clr-namespace:MyProject.ViewModels".
The error doesn't make sense MyViewModel does exist within the MyProject.ViewModels namspace.
Any suggestions? I've tried a clean rebuild.
The MyProject.ViewModels namepsace is within a different assembly to the MyProject.Views.Pages and it appears to necessary to add ;assembly=MyProject.ViewModels to the xmlns:ViewModels="clr-namespace:MyProject.ViewModels delcaration:
xmlns:ViewModels="clr-namespace:MyProject.ViewModels;assembly=MyProject.ViewModels"
I assumed that because the assembly is referenced by the project, I wouldn't need to specify an assembly, just as I don't have to specify an assembly when using a namespace within a C# code file.
I just got the same error and I got it many times before. Each time I have this error, it come from the fact that I have other errors and my code won't compile for other reasons. As soon as I fixed all other errors, my code compile and VisualStudio find all 'd:' missing references... if they really exists.
Also, as an alternative, if you instanciate your ViewModel with its default constructor, I suggest to use something like (without using 'd:'):
...
</Page>
<Page.DataContext>
<ViewModels:MyViewModel/>
</Page.DataContext>
It will solve your problem forever.
I haven't tried it yet, but perhaps that with Roslyn (the new VS2015 compiler) this problem will go away. I hope :-)

<i: Interaction.Behavior> option is not coming for applying beahviour

I have been trying to implement a behavior on a wpf window therefore I have added reference to System.Winodws.Interactivity in my current solution and then wrote the desired behavior. but in order to apply this behavior, I have to write something like this in Windows XAML.
<Window x:Class="WpfApplication5.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525"
xmlns:behav ="clr-namespace:WpfApplication5"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity;assembly=System.Windows.Interactivity">
<Window.Resources>
<i:Interaction.Behaviors>
<behav:DialogIconRemoveBehavior></behav:DialogIconRemoveBehavior>
</i:Interaction.Behaviors>
</Window.Resources>
<Grid>
</Grid>
</Window>
but this is not valid tag because I might have to add reference to any other assembly apart form System.Windows.Interactivity, So, please suggest what else
I have to do in order to use tag in XAML
After wasting my one hour I came to know that only I had to include System.Windows.Interactivity as reference and which I had already done.
the issue was that Behaviors can not be declared in the Resource part of any control.
the moment I took the following
<i:Interaction.Behaviors>
</i:Interaction.Behaviors>
out of the resources then it worked fine.
So, conclusion only System.Windows.Interacivity is the only required.
Never declare that behavior part in the resources or style.

Inconsistency between XAML intellisense and compiler for a control

I am converting some Silverlight XAML into WPF. I currently have a user control (MyControl) that is trying to include a couple of other controls that are custom buttons (MyButton1) that are within the same assembly. I have the following XAML that compiles and works in SL:
MyButton1
<UserControl
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"
mc:Ignorable="d"
x:Class="MyCompany.MyNamespace.MySubnamespace.MyButton1"
d:DesignWidth="640" d:DesignHeight="480">
...
</UserControl>
MyControl
<UserControl
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:somename="clr-namespace:MyCompany.MyNamespace.MySubnamespace;assembly=MyCompany.MyAssemblyName"
mc:Ignorable="d"
x:Class="MyCompany.MyNamespace.MySubnamespace.MyControl"
d:DesignWidth="640" d:DesignHeight="480">
<somename:MyButton1 />
</UserControl>
When I try to compile this code in WPF, I get the following error:
The tag 'MyButton1' does not exist in XML namespace 'clr-namespace:MyCompany.MyNamespace.MySubnamespace;assembly=MyCompany.MyAssemblyName.'
The weird thing is, if I comment out the <somename:MyButton1 /> line of code and compile and then type in <somename: IntelliSense gives me the option to autocomplete MyButton1. Which suggests that the control itself is in the assembly but for some reason it is not being seen when the MyControl XAML is being compiled.
For some context, I took the SL csproj file and made some modifications to it manually to make it a WPF csproj file. If there is a possibility that this caused this funkiness to happen, I'd be glad to share relevant portions of the project file.
Found the answer on an MSDN forum. Turns out that the assembly=MyCompany.MyAssemblyName line in my xmlns was screwing things up. Once I removed that line, I was able to reference the controls.
Related Link: http://social.msdn.microsoft.com/Forums/en/wpf/thread/807c9b80-81c7-4f75-aa2f-8427e17b1a90
To reference the current assembly you must not type its name but leave it blank, i.e. assembly=, the other option is of course to drop it completely. (MSDN -> Mapping to Current Assemblies)

Setting design time DataContext on a Window is giving a compiler error?

I have the following XAML below for the main window in my WPF application, I am trying to set the design time d:DataContext below, which I can successfully do for all my various UserControls, but it gives me this error when I try to do it on the window...
Error 1 The property 'DataContext' must be in the default namespace or in the element namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation'. Line 8 Position 9. C:\dev\bplus\PMT\src\UI\MainWindow.xaml 8 9 UI
<Window x:Class="BenchmarkPlus.PMT.UI.MainWindow"
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:UI="clr-namespace:BenchmarkPlus.PMT.UI"
xmlns:Controls="clr-namespace:BenchmarkPlus.PMT.UI.Controls"
d:DataContext="{d:DesignInstance Type=UI:MainViewModel, IsDesignTimeCreatable=True}"
Title="MainWindow" Height="1000" Width="1600" Background="#FF7A7C82">
<Grid>
<!-- Content Here -->
</grid>
</Window>
I needed to add the mc:Ignorable="d" attribute to the Window tag. Essentially I learned something new. The d: namespace prefix that Expression Blend/Visual Studio designer acknowledges is actually ignored/"commented out" by the real compiler/xaml parser!
<Window
...
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
...
/>
The following was taken from
Nathan, Adam (2010-06-04). WPF 4 Unleashed (Kindle Locations 1799-1811). Sams. Kindle Edition.
Markup Compatibility
The markup compatibility XML namespace (http://schemas.openxmlformats.org/markup-compatibility/2006, typically used with an mc prefix) contains an Ignorable attribute that instructs XAML processors to ignore all elements/attributes in specified namespaces if they can’t be resolved to their .NET types/members. (The namespace also has a ProcessContent attribute that overrides Ignorable for specific types inside the ignored namespaces.)
Expression Blend takes advantage of this feature to do things like add design-time properties to XAML content that can be ignored at runtime.
mc:Ignorable can be given a space-delimited list of namespaces, and mc:ProcessContent can be given a space-delimited list of elements. When XamlXmlReader encounters ignorable content that can’t be resolved, it doesn’t report any nodes for it. If the ignorable content can be resolved, it will be reported normally. So consumers don’t need to do anything special to handle markup compatibility correctly.
Wow, what a pain! Let's hope MS puts in some VS design-time support for x:Bind.
We to be able to use the VS designer but also be able to switch easily to x:Bind instead of Binding. Here's what I did:
In my View, I added a property to get my ViewModel. This makes sense because x:Bind paths are relative to the Page (i.e. the View object).
In my Page XAML, I added the following to the <Page ... > at the top of the XAML:
mc:Ignorable="d"
d:DataContext="{d:DesignInstance Type=local:MyView, IsDesignTimeCreatable=False}"
DataContext="{x:Bind}"
This way, the Page's actual data context is set to the Page itself due to the {x:Bind}. That's because x:Bind is relative to the Page and there is no path given.
At the same time, due to the d:DataContext line, the VS designer reflects on the MyView class (without creating an instance) for the purpose of the VS designer interaction. This lets VS design from MyView, where you can then scroll down to the ViewModel property, expand it and select the item that you want to bind to.
When you do all that, the VS designer will create a Binding statement whose path is relative to the View, i.e. it happens to be exactly the same as the path that x:Bind expects. So, if you want to switch to x:Bind later on, you can just search and replace all "{Binding" with "{x:Bind".
Why do we even need the d:DataContext line to tell VS what class to look at? Good question, since you would think that VS could figure out the very next line sets the DataContext to the Page, using DataContext={x:Bind}. Go ahead and try it, it does not work and neither does it work if you change x:Bind to Binding relative to self.
Hopefully this situation will get cleaned up by MS !!
If you are not tooo fussy on the data have a look at the sample data found in xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
You use it like this...
<ItemsControl ItemsSource="{Binding Path=Report.Audit.Data}" d:ItemsSource="{d:SampleData}" Grid.Row="1">
<ItemsControl.ItemTemplate>
<DataTemplate>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
it then renders the items control with a few rows of data
I've solved the problem adding d:DataContext="{d:SampleData}" in the component definition (UserControl or Window).
<UserControl x:Class="TestControl"
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:TestApp.Views"
DataContext="{Binding TestViewModel}"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800"
d:DataContext="{d:SampleData}"
>

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