I've trawled the entire internet, every forum, every blog, ever, anywhere. I now literally contain the internet... except this one last thing ;-). Here's the problem: I have a WPF DataGrid that has a column defined thus:
<tk:DataGridTemplateColumn Header="First name" Width="100" x:Name="colFirstName">
<tk:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBox x:Name="tbFirstName" Validation.ErrorTemplate="{DynamicResource errorTemplateYourDetailsGrid}">
<TextBox.Text>
<Binding Path="Firstname" UpdateSourceTrigger="PropertyChanged" NotifyOnValidationError="True">
<Binding.ValidationRules>
<val:RequiredValidationRule ErrorMessage="Invalid or missing first name" ValidatesOnTargetUpdated="True"></val:RequiredValidationRule>
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>
</DataTemplate>
</tk:DataGridTemplateColumn.CellTemplate>
</tk:DataGridTemplateColumn>
As you can see I've defined a Validation template called errorTemplateYourDetailsGrid.
The page has a continue button that I want to disable until all the fields in this grid are valid:
<Button x:Name="btnNext" HorizontalAlignment="Right" DockPanel.Dock="Right" Content="Continue" Command="{Binding YourDetailsNextCommand}" >
<Button.Style>
<Style TargetType="Button" BasedOn="{StaticResource BtnContinue}">
<Setter Property="IsEnabled" Value="false" />
<Style.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding ElementName=tbFirstName, Path=(Validation.HasError)}" Value="false" />
<Condition Binding="{Binding ElementName=tbSurname, Path=(Validation.HasError)}" Value="false" />
...etc
</MultiDataTrigger.Conditions>
<Setter Property="IsEnabled" Value="true" />
</MultiDataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
A colleague has got this sort of thing working fine with a straight form-based layout (not using a datagrid). So I'm guessing I need some syntax that will reference the TextBox in the cell in the column in the DataGrid so that the Triggers fire. Simply using ElementName isn't working. The button stays disabled even though the validation template disappears as expected when you enter text into those fields.
I'm using MVVM so any code behind-based solution isn't an option.
The MVVM way of performing validations is using INotifyDataErrorInfo (or IDataErrorInfo if you're using .NET 4.0 or below), so you won't define validation logic in your XAML, but in your model and viewmodel classes.
Once you implement it, you'll have one central place to query for errors and you could bind your button's trigger to your viewmodel's INotifyDataErrorInfo.HasErrors property.
Check these articles to see if they can help you find the data template elements:
How to: Find DataTemplate-Generated Elements
C#/WPF: Get Binding Path of an Element in a DataTemplate
Related
With Xamarin, I have a small UI element which acts as a content divider:
<BoxView StyleClass="contentDivider"
HeightRequest="2"
WidthRequest="1000"
Margin="3, 0"/>
Since I use this a number of times I wanted to be able to have the code written down once, and reuse that code - just like a class with its instance (DRY). It's most likely me being a blind bat and not being able to find how it's done. So, how can I reuse XAML elements?
You can do this with ContentViews (https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/controls/layouts#contentview), which probably works better for larger reuse cases (using more XAML in the ContentView).
Yet, for such a small single element example as yours, you could really just consider using a global style (https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/styles/xaml/application) which its looks like you already have with StyleClass="contentDivider", as long as you only want to override properties on a single element (like your BoxView).
Just add HeightRequest, WidthRequest and Margin to your style and your done.
<Style x:Key="contentDivider" TargetType="BoxView">
<Setter Property="HeightRequest" Value="20" />
<Setter Property="WidthRequest" Value="20" />
<Setter Property="Margin" Value="0,99,0,0" />
... etc
</Style>
I'm making a ResourceDictionary of common styles that are used throughout my application and one of them is:
<Style x:Key="ME_BASE_AppbarButtonSaveStyle"
TargetType="AppBarButton">
<Setter Property="Label"
Value="Save" />
<Setter Property="ToolTipService.ToolTip"
Value="Save" />
<Setter Property="Icon">
<Setter.Value>
<FontIcon FontFamily="Segoe MDL2 Assets"
Glyph="" />
</Setter.Value>
</Setter>
</Style>
It's all ok if I apply the style only one AppbarButton on the Page, but if I want to have two buttons with the same style, I get the following error:
The parameter is incorrect
It's of ok (no error) if I remove the icon property out of the style...
But that's kind of missing the point...
Anyone experienced something similar? Perhaps...
Thank you for all the help.
Error HRESULT E_Fail has been returned from a call to a COM component.
This error will occurred when you use this style for the second AppBarButton. This error usually happens when a reference to a style or an event handler that does not exist or is not with the context of the XAML, you can see the exception information of your problem:
If you read this document: XAML resources must be shareable, you will find:
Custom types used as resources can't have the UIElement class in their inheritance, because a UIElement can never be shareable (it's always intended to represent exactly one UI element that exists at one position in the object graph of your runtime app).
Whether a Icon property of AppBarButton or a FontIcon derives from UIElement, so I guess this is the reason why can't this property be styled in the resource dictionary.
Besides, I will consider if this is a right direction to define the Icon property for each AppBarButton in the style, normally I'd like give each button a different icon as content.
But if you insist to do this, I can provide you a workaround method by defining the Content of the AppBarButton, this is the construction of your AppBarButton:
You use a FontIcon as the content of the AppBarButton, so we can modify your style like this:
<Style x:Key="ME_BASE_AppbarButtonSaveStyle" TargetType="AppBarButton">
<Setter Property="Label" Value="Save" />
<Setter Property="ToolTipService.ToolTip" Value="Save" />
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<FontIcon FontFamily="Segoe MDL2 Assets"
Glyph="" />
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
Given a style in a Page.Resource:
<Style x:Name="ItemTitle" TargetType="TextBlock">
<Setter Property="FontSize" Value="16"></Setter>
<Setter Property="FontWeight" Value="Bold"></Setter>
</Style>
It is correctly applied to any regular TextBlock on the same page.
However, when I use a DataTemplate for an Item in a GridView on that page, this style does not apply.
<DataTemplate x:Key="Output" x:DataType="vm:Output">
<TextBlock Text="{x:Bind Text}"></TextBlock>
</DataTemplate>
It does work when I apply the style explicitly on the DataTemplate, e.g.:
<DataTemplate x:Key="Output" x:DataType="vm:Output">
<TextBlock Style="{StaticResource ItemTitle}" Text="{x:Bind Text}"></TextBlock>
</DataTemplate>
Does anyone know what's up?
It's expected and intentional. If it doesn't derive from Control (like DataTemplate) then it won't inherit an implicit style unless they're in the application resource dictionaries as global defaults.
Or more specifically;
Templates are viewed as an encapsulation boundary when looking up an implicit style for an element which is not a subtype of Control.
Hope this helps. Cheers.
Addendum:
If it's a situation where you have a lot of the same element nested in a Template you can just set it once and allow it to inherit to all the nested controls of the type like (in pseudo);
<Parent>
<Parent.Resources>
<Style TargetType="TextBlock" BasedOn="{StaticResource ItemTitle}"/>
<Parent.Resources>
<!-- These will all inherit the Style resource now,
without explicit style setting individually. -->
<TextBlock/>
<TextBlock/>
<TextBlock/>
</Parent>
When using a listitem in a w8 app, how can I determine what gives the hover and click styles?
My listview looks like this:
<ListView x:Name="itemsListView"
TabIndex="1"
Visibility="Visible"
Padding="10,0,0,0" Foreground="Black"
ItemsSource="{Binding Nodes.Nodes}"
behaviors:ListViewItemClickedToAction.Action="{Binding SelectNodeAction}"
IsItemClickEnabled="True" FontFamily="Global User Interface"
>
<ListView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
When I hover using the mouse I get white letters and an almost white background.
I have tried reusing parts of the adventureworks shopper app, so there are styles from there copied. However, I can't understand what is applied to the ListView items.
You maybe already new this but if you check this screenshot you can see how you easily in VS2012 can create a copy of a built in style. When you press the "Edit a copy ..." a dialog will appear where you can choose where in the Project you want the style to be placed.
You can inherit styles. The inheritence of styles work in the following way:
<Style x:Name="BasicStyle" TargetType="Button">
<Setter Property="Background" Value="Green" />
</Style>
<Style x:Name="ButtonStyle" TargetType="Button" BasedOn="{StaticResource BasicStyle}">
<Setter Property="Foreground" Value="Red" />
</Style>
You can do inheritence in several steps so Another button style can inherit the "ButtonStyle".
You can thus make a style that only contains the Template property if you want to seperate it or reuse the behaviour and look of your style. But you cannot split the Visual State Manager into several styles since if you inherit a style which sets the template property and then if you want to change the Hover state of that style you need to make a copy of the whole template and only change that part in the code.
I Think this would be a nice improvement by MS if you could make a style which only contains the pressed state and then Another style which only contains the hover effect and so on.
I hope this answers your questions :) I would love to answer more questions regarding XAML if you have any!
I have entity with property IsRemoved. When it is become true grid row should be Gray.
To do this I am using this code:
<dxg:TableView.RowStyle>
<Style TargetType="{x:Type dxg:GridRowContent}">
<Style.Triggers>
<DataTrigger Binding="{Binding DataContext.IsRemoved, Mode=OneWay}" Value="True">
<Setter Property="Background" Value="Gray" />
</DataTrigger>
</Style.Triggers>
</Style>
</dxg:TableView.RowStyle>
</dxg:TableView>
But It will run only when grid shows first time. I want to change color when value is changing. Property implement INotifyPropertyChange Event.
Note: this answer is legacy (see my other answer).
This answer is for DevExpress versions prior to v14.1, or DevExpress versions v14.1 and after with
UseLightweightTemplates="None".
You need to have an initial setter for the property you want to change. This is due to the order in which WPF uses styles.
Include this line after your style tag:
<Setter Property="Background" Value="Black" />
Full Example:
<dxg:TableView.RowStyle>
<Style TargetType="{x:Type dxg:GridRowContent}">
<Setter Property="Background" Value="Black" />
<Style.Triggers>
<DataTrigger Binding="{Binding DataContext.IsRemoved, Mode=OneWay}" Value="True">
<Setter Property="Background" Value="Gray" />
</DataTrigger>
</Style.Triggers>
</Style>
</dxg:TableView.RowStyle>
Starting with v14.1 of DevExpress, they introduced Optimized Mode which uses Lightweight Templates. This makes everything faster, but requires a change to how the styles and DataTriggers are specified.
Lightweight Templates are controlled by a the attached property UseLightweightTemplates="Row", which is on by default. It can be switched to None for backwards compatibility.
Here is a working MVVM example of how to color a row if the IsDirty property is set for any grid row.
<dxg:GridControl x:Name="MyGridControl"
ItemsSource ="{Binding MyViewModelList}"
SelectionMode="None"
VerticalAlignment="Stretch">
<dxg:GridControl.Resources>
<SolidColorBrush x:Key="GridRowIsDirty" Color="#FF602D2D" />
</dxg:GridControl.Resources>
<dxg:GridControl.View>
<dxg:TableView UseLightweightTemplates="Row" >
<dxg:TableView.RowStyle>
<Style TargetType="dxg:RowControl">
<Style.Triggers>
<DataTrigger Binding="{Binding Row.IsDirty}" Value="True">
<Setter Property="Background" Value="{StaticResource GridRowIsDirty}" />
</DataTrigger>
</Style.Triggers>
</Style>
</dxg:TableView.RowStyle>
</dxg:TableView>
</dxg:GridControl.View>
<dxg:GridControl.Columns>
<dxg:GridColumn x:Name="Included" FieldName="Included"/>
<dxg:GridColumn x:Name="ColumnB" Header="Column B" FieldName="ColumnB" ReadOnly="True"/>
<dxg:GridColumn x:Name="ColumnC" Header="Column C" FieldName="ColumnC" ReadOnly="True"/>ReadOnly="True"/>
</dxg:GridControl.Columns>
</dxg:GridControl>
In the ViewModel behind this grid:
public ObservableCollection<MyViewModel> MyViewModelList { get; set; }
Every row in the grid points to a class of type MyViewModel, which contains a custom IsDirty flag which we can set on demand:
public bool IsDirty
{
get { return _isDirty; }
set
{
_isDirty = value;
OnPropertyChanged();
}
}
Appendix A: Additional Links
See DevExpress: How to disable focused/selected row colors.
See DevExpress: Optimized Mode.
See DevExpress: DXGrid: DataTrigger does not seem to work with UseLightweightTemplates="All".
See DevExpress: Binding to the RowData.Row property is not updated when changing a specific data row property.
See DevExpress: DxGrid: Grid does not update until I scroll the row on off and one the screen.
Appendix B: Other solutions
This also works most of the time, but it will not work if the source of the event is via a context menu, so it is not recommended:
<DataTrigger Binding="{Binding DataContext.IsDirty}" Value="True">
<Setter Property="Background" Value="{StaticResource GridRowIsDirty}" />
</DataTrigger>
Appendix C: AllowLiveDataShaping
If the trigger is not firing, try switching on AllowLiveDataShaping="True" in <GridControl>. However, try to avoid this as it (theoretically) has an impact on the speed of large, complex grids (it has no discernable impact on most grids of a reasonable size).
Appendix D: If all else fails, use a custom ControlTemplate
With the introduction of "UseLightweightTemplates", DevExpress has been focusing on speed. However, the techniques used for speed involve switching off bindings that might slow things down.
This means that if we change something in a DxGrid cell, the value in the ViewModel does not change until the user shifts to the next cell or row. This means that the ViewModel lags behind what is actually in the grid.
To fix this, the only solution that I could find was to bypass DevExpress's templates entirely, and use my own. This means that the DxGrid has no choice but to display a custom template which updates the ViewModel instantaneously as soon as the user edits it, which means that the row color changes immediately:
<dxg:GridControl Grid.Row="3" x:Name="TrsGridControl"
ItemsSource ="{Binding MyObservableCollection}"
VerticalAlignment="Stretch"
AllowLiveDataShaping ="True">
<dxg:GridControl.Resources>
<converter:TestConverter x:Key="TestConverter" />
<ControlTemplate x:Key="DisplayedOnTicketTrs">
<dxe:CheckEdit x:Name="DisplayedOnTicketCheckEdit" HorizontalAlignment="Center" IsChecked="{Binding RowData.Row.DisplayedOnTicket, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</ControlTemplate>
</dxg:GridControl.Resources>
<dxg:GridControl.View>
<dxg:TableView UseLightweightTemplates="All"/>
</dxg:GridControl.View>
<dxg:GridControl.Columns>
<dxg:GridColumn x:Name="DisplayedOnTicketTrs" DisplayTemplate="{StaticResource DisplayedOnTicketTrs}" Header="Displayed On Ticket?" HeaderToolTip="Displayed On Ticket?" AllowEditing="False"/>
Header ="Displayed On Ticket?"/>
<dxg:GridColumn x:Name="ColumnA" Header="ColumnA" FieldName="ColumnA" ReadOnly="True"/>
<dxg:GridColumn x:Name="ColumnB" Header="ColumnB" FieldName="ColumnB" ReadOnly="True"/>
</dxg:GridControl.Columns>
</dxg:GridControl>
After I made this change, everything started to work:
When the checkbox is clicked, the background color changes instantly (if we add the trigger to change the background color, above).
Editing the DxGrid changes the ViewModel instantaneously.
Changing the ViewModel updates the DxGrid instantaneously.
If a ContextMenu updates the ViewModel, then everything just works.
you should write just "Row" instead of "DataContext"