I have a user control called HomePage.xaml. I'm creating a model instance (using MVVM pattern) in the code behind file in the constructor of page as
MainViewModel model = new MainViewModel();
I have a button in HomePage.xaml which I want to bind to the command inside MainViewModel called GetData() and want to populate the data in datagrid. MainViewModel has an ObservableCollection which I would use to bind the data in datagrid.
Populating the data in datagrid without binding command works fine.
I'm binding the button as:
<StackPanel x:Name="stkPanelInput" Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Center">
<Button x:Name="buttonGetData" Width="70" Content="GetData" Command="{Binding GetData}" Click="buttonGetData_Click"/>
</StackPanel>
How shall I bind the command using MVVM?
Like Archie said, set the DataContext of your page to the instance of your MainViewModel.
DataContext = model;
Then you have your XAML look like this:
<StackPanel x:Name="stkPanelInput" Orientation="Horizontal" VerticalAlignment="Center" HorizontalAlignment="Center">
<Button x:Name="buttonGetData" Width="70" Content="GetData" Command="{Binding GetDataCommand}" Click="buttonGetData_Click"/>
</StackPanel>
Related
I want to make a xamarin forms carousel view containing 2 custom views. I have this code:
<ContentPage x:Class="MainView" xmlns:mvvm="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" xmlns:views="clr-namespace:Views" x:Name="Main">
<CarouselView>
<CarouselView.ItemsSource>
<x:Array Type="{x:Type View}">
<views:View1 mvvm:ViewModelLocator.AutowirePartialView="{x:Reference Main}" />
<views:View2 mvvm:ViewModelLocator.AutowirePartialView="{x:Reference Main}" />
</x:Array>
</CarouselView.ItemsSource>
<CarouselView.ItemTemplate>
<DataTemplate>
<ContentView Content="{Binding .}" />
</DataTemplate>
</CarouselView.ItemTemplate>
</CarouselView>
</ContentPage>
When launching the app, exception is thrown:
Xamarin.Forms.Xaml.XamlParseException: 'Position 80:37. Can not find
the object referenced by Main'
If I just set both views as direct content of the main page, it works fine. What am I doing wrong?
Is there a way to make the collection of views through the MainViewModel?
I'm working in a web application using ZK. I'm struggling with a window where I need to render a grid with as much rows as the user specifies. It should be something like:
<grid>
<columns>
<column width="150px"/>
<column width="350px"/>
</columns>
<rows>
<row>
<cell>
<label value="Rows to add"/>
</cell>
<cell>
<textbox id="txt_rowamount"/>
</cell>
</row>
</rows>
</grid>
<grid id="grid">
<columns>
<column width="100px" label="Field 1" align="center"/>
<column width="100px" label="Field 2" align="center"/>
<column width="100px" label="Field 3" align="center"/>
</columns>
<rows id="rows" forEach="${rowModelList}">
<row>
<cell>
<textbox value="${each.field1}" />
</cell>
<cell>
<textbox value="${each.field2}" />
</cell>
<cell>
<textbox value="${each.field3}" />
</cell>
</row>
</rows>
</grid>
<button id="btn_generate" label="Generate Rows"/>
So, if you type 4 in txt_rowamount a grid with 4 row components and 3 textbox components in each row. The textboxes should be empty and when I complete every textbox the user input should be binded to fieldN of every rowModel item, do I make myself clear?
I'm trying with something like this in the composer:
private ListModel<RowModel> rowModelList;
#Autowired
private Grid grid;
#Override
public void doAfterCompose(final Window component) throws Exception {
super.doAfterCompose(component);
rowModelList = new ListModelList<>();
grid.setVisible(false);
}
public void onClick$btn_generate() {
// TODO Add four empty elements to rowModelList
grid.setVisible(true);
}
Being RowModel like
public class RowModel {
private String field1;
private String field2;
private String field3;
// ommited constructors, getters and setters
}
I believe that the approach should be MVVM instead of the current MVC but I don't know how to do this. Besides, I don't know if you can mix the approachs in the same application and what are the advantages and disadvantages of doing that.
I've seeing the ZK grid demos but all of them are using already populated objects to render the tables, so it's not useful to me.
If someone can give me a hand in this issue, it would be greatly appreciated. If you need more information on the code or the requirements for this problem, please comment it out.
Thanks in advance for your answers.
It seems there's a lot missing in your current attempt, so I'll try to fill the gaps.
If impatient here a runnable example on zkfiddle.
Since you were talking about binding component attributes to model values I'd suggest using ZK's DataBinding which integrates nicely into the MVVM development pattern (sorry for the link, but that's not a one-liner).
In any case the example illustrates how to combine ZK features such as (ListModelList with templates, Property-/Command-Binding) into a simple dynamic UI.
As you can see in code, adding, (re)moving a row inside the model requires rudimentary operations (the grid will update its child-rows automatically):
rows.add(new RowModel(...));
rows.remove(row);
Since the ListModelList is assigned to the <grid> component via #init(vm.rows), the grid will listen to changes to the ListModel and add remove grid-rows accordingly. It uses the <template name="model" var="rowModel"> to render new rows when added to the model. The template variable rowModel variable represents the rowModel object. (more on that in our documentation)
I hope this information is not overwhelming ... if so please let me know.
BTW: the forEach-attribute you were trying to use previously is used for static ui composition (at zul parse time) where no dynamic control is required. For dynamic cases use ListModel(List) in combination with templates.
Robert
I'm trying to do a DropDownButton (or ComboButton) in Pure XAML because I want to use the GUI in PowerShell.
I'm aware of wpftoolkit's DropDownButton but it needs custom C#/c++ code to make it work.(and if I could bring it in, the wpftoolkit would be bigger than my project!)
Below I just stacked a Button control on top of a comboBox control. (Ugly, I know but my options are limited from my point of view)
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Height="580"
MinHeight="580"
MinWidth="700"
Width="700"
Background="lightgray">
<Grid>
<ComboBox
x:Name="CboxWakeUp"
Width="100"
Height="80"
HorizontalAlignment="Right"
Margin="10,10,10,0"
VerticalAlignment="Top"
Background="green"
IsEditable="True"
IsReadOnly="True"
TextBlock.FontSize="16"
>
<ComboBoxItem Content="WakeUp and RDP" IsSelected="True"/>
<ComboBoxItem Content="WakeUp from list"/>
<ComboBoxItem Content="WakeUp and Run"/>
</ComboBox>
<!-- Button is ON TOP of ComboBox -->
<Button
Name="btnWakeUp"
Width="85"
Height="80"
HorizontalAlignment="Right"
Margin="10,10,25,0"
VerticalAlignment="Top"
Background="green"
TextBlock.FontSize="16"
>
<!-- This would makes the SelectedValue text wrap but the binding binding syntax used is taken literally -->
<TextBlock Text="{Binding SelectedValue, ElementName=CboxWakeUp}" TextWrapping="Wrap" TextAlignment="Center"/>
</Button>
</Grid>
</Window>
I'm close but I need help.
I need to wrap the text of the button and I have figured it out by embedding a TextBlock control inside the Button control (Thank you TheMadTechnician! ) but the binding syntax I used in the button is taken literally.
NOTE: I had the binding to the button working directly but when a selection was made in the ComboBox, Kaxaml gave me "Must disconnect specified child from current parent Visual before attaching to new parent Visual" error. I'm hoping the TextBlock control will side-step this issue.
PS: I was going to try to make the button change colour based on the selection made in the ComboBox:
WakeUp and RDP ==> Green
WakeUp from list ==> Blue
WakeUp and Run ==> Red
This will have to be done in PS code and that's ok
I'm trying to use MVVMLight to bind a TreeViewItem Selected event to a command.
The TreeViewItem's are defined in a HierarchicalDataTemplate so I cannot add Interaction.Triggers (as shown below)
<HierarchicalDataTemplate
x:Key="TreeViewItemTemplate"
ItemsSource="{Binding ChildReportViewModels}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Selected">
<MvvmLight_Command:EventToCommand Command="{Binding LoadReportCommand, Mode=OneWay}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</HierarchicalDataTemplate>
How else can I add the EventTrigger to each TreeViewItem?
Thanks.
I forgot about this question.
For future ref, here's the solution I used...
Instead of trying to bind the EventToCommand to the Selected event of the TreeView,
I bound it to the MouseLeftButtonUpEvent of the TextBlock declared in the HierarchicalDataTemplate for TreeViewItems.
<HierarchicalDataTemplate
x:Key="TreeViewItemTemplate"
ItemsSource="{Binding ChildReportViewModels}"
ItemContainerStyle="{StaticResource TreeViewItemContainerStyle}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="MouseLeftButtonUp">
<gs_cmd:EventToCommand Command="{Binding LoadPublicationCommand, Mode=OneWay}" CommandParameter="{Binding}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBlock>
</StackPanel>
</HierarchicalDataTemplate>
I have not much knowledge about MVVMLight and especially about EventTrigger.
But since there is no answer to your qestion yet the codeplex article TreeViewWithViewModel might help. It shows how to bind to SelectedItem and IsExpanded Properties in a wpf-treeview and how these can be used to implement load on demand in the treeview.
I am using MVVM in my application and binding combobox to my collection. However when i run it the combobox doesn't have any selected index and it shows a ugly emtpy box. How do i get past this issue?
This is my code :-
<ComboBox x:Name="cmbPasswordQuestion" ItemsSource="{Binding PasswordQuestionList}" DisplayMemberPath="SiteTermsXItemsName" SelectedValuePath="SiteTermsXItemId" SelectedValue="{Binding SignUpUser.PasswordQuestionId}" Margin="97,210,247,0" VerticalAlignment="Top" Height="24">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding PasswordQuestionCommand}" CommandParameter="{Binding SelectedItem, ElementName=cmbPasswordQuestion}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</ComboBox>
I am not able to set the SelectedIndex = 0 directly in xaml as i am binding the collection run time.
Thanks in advance :)
All you need is to set SignUpUser.PasswordQuestionId to the id of the first item in the combobox right after you initialized the PasswordQuestionList property. And the binding will do the rest.