Could any body explain why if I have protected property in control it couldn't be set from .aspx?
Control:
public partial class SomeUserControl : UserControl
{
protected bool SomeProperty
{
get { return ViewState["SomeProperty"] != null && (bool) ViewState["SomeProperty"]; }
set { ViewState["SomeProperty"] = value; }
}
...
}
Declaration in .aspx:
<custom:SomeUserControl ID="SomeUserControl1" runat="server" SomeProperty="true"/>
When I am trying to debug setter never called.
Just realized that it wasn't visible with intellisense. And this property recognized like as HTML attribute.
Related
I'm currently refactoring a few abstraction layers into a Xamarin app in order to break the "monolithic" structure left by the previous dev, but something has gone awry. In my ViewModel, I have a few properties that call NotifyPropertyChange in order to update the UI whenever a value is picked from a list. Like so:
public Notifier : BindableObject, INotifyPropertyChanged
{
//...
protected void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Had to create a middle layer due to my specific needs
public interface ISomeArea
{
DefinicaoServicoMobile TipoPasseio { get; set; }
}
-
public class SomeAreaImpl : Notifier, ISomeArea
{
//...
protected DefinicaoServicoMobile _tipoPasseio;
public DefinicaoServicoMobile TipoPasseio
{
get => _tipoPasseio;
set
{
if (_tipoPasseio != value)
{
_tipoPasseio = value;
NotifyPropertyChanged(nameof(TipoPasseio));
}
}
}
}
The actual bound view model:
public MyViewModel : BaseViewModel, ISomeArea
{
private SomeAreaImpl someArea;
//...
public MyViewModel()
{
// This is meant to provide interchangable areas across view models with minimal code replication
someArea = new SomeAreaImpl();
}
public DefinicaoServicoMobile TipoPasseio
{
get => someArea.TipoPasseio;
set => someArea.TipoPasseio = value;
}
}
And the .xaml snippet:
<renderers:Entry
x:Name="TxtTipoPasseio"
VerticalOptions="Center"
HeightRequest="60"
HorizontalOptions="FillAndExpand"
Text="{Binding TipoPasseio.DsPadrao}"
/>
The renderer opens a list allowing the user to choose whichever "TipoPasseio" they want, and supposedly fill the textbox with a DsPadrao (standard description). Everything works, even the reference to TipoPasseio is held after being selected (I know this because should I bring up the list a second time, it will only display the selected DsPadrao, giving the user the option to clean it. If he does, a third tap will show all the options again.
I might have screwed up in the abstraction, as I don't see the setter for myViewModel.TipoPasseio being called, tbh
Any ideas?
Let's reason through what Xamarin knows (as best as we can, since you didn't include all of the relevant code):
You have a data context having the type MyViewModel
That view model object has a property named TipoPasseio, having type DefinicaoServicoMobile
The type DefinicaoServicoMobile has a property named DsPadrao
It is that last property that is bound to the Entry.Text property.
In a binding, any observable changes to values forming the source or path for the binding will cause the runtime to update the target property for the binding (Entry.Text) and thus result in a change in the visual appearance (i.e. new text being displayed).
Note the key word observable. Here are the things I see which are observable by Xamarin:
The data context. But this doesn't change.
That's it.
With respect to the value of the MyViewModel.TipoPasseio property, there's nothing in the code you posted showing this property changing. But if it did, it doesn't look like MyViewModel implements INotifyPropertyChanged, so Xamarin wouldn't have a way to observe such a change.
On that second point, you do implement INotifyPropertyChanged in the SomeAreaImpl type. But Xamarin doesn't know anything about that object. It has no reference to it, and so has no way to subscribe to its PropertyChanged event.
Based on your statement:
I don't see the setter for myViewModel.TipoPasseio being called
That suggests that the TipoPasseio property isn't being changed. I.e. while you wouldn't be providing notification to Xamarin even if it did change, it's not changing anyway.
One property that does seem to be changing is the DsPadrao property (after all, it's the property that's actually providing the value for the binding). And while you don't provide enough details for us to know for sure, it seems like a reasonable guess that the DefinicaoServicoMobile doesn't implement INotifyPropertyChanged, and so there's no way for Xamarin to ever find out the value of that property might have changed either.
In other words, of all the things that Xamarin can see, the only one that it would be notified about of a change is the data context. And that doesn't seem to be what's changing in your scenario. None of the other values are held by properties backed by INotifyPropertyChanged.
Without a complete code example, it's impossible to know for sure what the right fix is. Depending on what's changing and how though, you need to implement INotifyPropertyChanged for one or more of your types that don't currently do so.
As it turns out, I wasn't firing the NotifyPropertyChanged of the correct object. Both MyViewModel and SomeAreaImpl implemented INotifyPropertyChanged per the Notifier class as BaseViewModel also extends from Notifier but that ended up ommited in my question. Having figured that out, here's an working (and complete) example:
public Notifier : BindableObject, INotifyPropertyChanged
{
//...
protected void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Specifics about DefinicaoServicoMobile are negligible to this issue
public interface ISomeArea
{
//...
DefinicaoServicoMobile TipoPasseio { get; set; }
Task SetServico(ServicoMobile servicoAtual;
//...
}
For the sake of clarification
public abstract class BaseViewModel : Notifier
{
protected abstract Task SetServico(ServicoMobile servicoAtual);
public async Task SetServico()
{
//...
await SetServico(servicoAtual);
//...
}
}
Changed a couple of things here. It no longer extends from Notifier, which was kinda weird to begin with. Also this is where I assign TipoPasseio
public class SomeAreaImpl : ISomeArea
{
//...
protected DefinicaoServicoMobile _tipoPasseio;
// I need to call the viewModel's Notifier, as this is the bound object
private BaseViewModel viewModel;
public AreaServicosDependentesImpl(BaseViewModel viewModel)
{
this.viewModel = viewModel;
}
public DefinicaoServicoMobile TipoPasseio
{
get => _tipoPasseio;
set
{
if (_tipoPasseio != value)
{
_tipoPasseio = value;
viewModel.NotifyPropertyChanged(nameof(TipoPasseio));
}
}
}
//Assigning to the property
public async Task SetServico(ServicoMobile servicoAtual, List<DefinicaoServicoMobile> listDefinicaoServico)
{
//...
TipoPasseio = listDefinicaoServico
.FirstOrDefault(x => x.CdServico == servicoAtual.TpPasseio.Value);
//...
}
}
Changes to the view model:
public MyViewModel : BaseViewModel, ISomeArea
{
private SomeAreaImpl someArea;
//...
public MyViewModel()
{
someArea = new SomeAreaImpl(this);
}
public DefinicaoServicoMobile TipoPasseio
{
get => someArea.TipoPasseio;
set => someArea.TipoPasseio = value;
}
protected override async Task SetServico(ServicoMobile servicoAtual)
{
//...
someArea.SetServico(servicoAtual, ListDefinicaoServico.ToList());
//...
}
}
View model binding
public abstract class BaseEncerrarPontoRotaPage : BasePage
{
private Type viewModelRuntimeType;
public BaseEncerrarPontoRotaPage(Type viewModelRuntimeType)
{
this.viewModelRuntimeType = viewModelRuntimeType;
}
private async Task BindContext(PontoRotaMobile pontoRota, ServicoMovelMobile servicoMovel, bool finalizar)
{
_viewModel = (BaseViewModel)Activator.CreateInstance(viewModelRuntimeType, new object[] { pontoRota, UserDialogs.Instance });
//...
await _viewModel.SetServico();
//...
BindingContext = _viewModel;
}
public static BaseEncerrarPontoRotaPage Create(EnumAcaoServicoType enumType)
{
Type pageType = enumType.GetCustomAttribute<EnumAcaoServicoType, PageRuntimeTypeAttribute>();
Type viewModelType = enumType.GetCustomAttribute<EnumAcaoServicoType, ViewModelRuntimeTypeAttribute>();
return (BaseEncerrarPontoRotaPage)Activator.CreateInstance(pageType, new object[] { viewModelType });
}
}
Page instantiation is performed in some other view model, not related to the structure presented here
private async Task ShowEdit(bool finalizar)
{
await Task.Run(async () =>
{
var idAcaoServico = ServicoMobileAtual.DefinicaoServicoMobile.IdAcaoServico;
var page = BaseEncerrarPontoRotaPage.Create((EnumAcaoServicoType)idAcaoServico);
await page.BindContext(PontoRotaAtual, ServicoMovelMobileAtual, finalizar);
BeginInvokeOnMainThread(async () =>
{
await App.Navigation.PushAsync(page);
});
});
}
Codebehind:
public partial class MyPage : BaseEncerrarPontoRotaPage
{
public NormalUnidadePage() { }
public MyPage(Type viewModelType) : base(viewModelType)
{
InitializeComponent();
//Subscription to show the list
TxtTipoPasseio.Focused += TxtTipoPasseio_OnFocused;
//...
}
}
XAML
<views:BaseEncerrarPontoRotaPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:views="clr-namespace:My.Name.Space.;assembly=Phoenix.AS"
x:Class="My.Name.Space.MyPage">
//...
<renderers:Entry
x:Name="TxtTipoPasseio"
VerticalOptions="Center"
HeightRequest="60"
HorizontalOptions="FillAndExpand"
Text="{Binding TipoPasseio.DsPadrao}"/>
//...
</views:BaseEncerrarPontoRotaPage>
I know could propagate an event from the AreaImpl classes in order to fire the Notify event in the view model, but right now I'm satisfied with this solution.
I'm making app with using Xamarin.forms.
I set BindableProperty of integer.
But it's setter never called and not even set from xaml.
<... SelectedIndex="{Binding myValue}">
Is there anything I did wrong?
Thanks.
public class CircleSegmentControl : StackLayout
{
public static readonly BindableProperty SegmentInitialIndexProperty = BindableProperty.Create("SelectedIndex", typeof(int), typeof(CircleSegmentControl), 0);
public int SelectedIndex {
set{
Debug.WriteLine("setter");
SetValue(SegmentInitialIndexProperty, value);
SelectIndex(value);
}
get{
Debug.WriteLine("getter");
return (int)GetValue(SegmentInitialIndexProperty);
}
}
...
}
Apparently the same applies as for WPF dependency properties. You must not call anything else than GetValue and SetValue in the get and set methods of the property wrapper:
public int SelectedIndex
{
get { return (int)GetValue(SelectedIndexProperty); }
set { SetValue(SelectedIndexProperty, value); }
}
To get notified about property value changes (to call your SelectIndex method), you should register a propertyChanged delegate with another overload of BindableProperty.Create.
I am trying to reproduce the behaviour found in some WinForms controls (such as DataGridView and DataGridViewColumn) where the child object has a property pointing to the parent. This property is normally readonly, but it somehow changes after the parent's Add() method has been called.
In my code I have two classes, DataGroup and DataEntry, with the latter being the child object.
If I simply implemented something like:
public class DataEntry
{
public DataGroup Parent { get; set; }
}
public class DataGroup
{
public List<DataEntry> DataEntries { get; set; }
public DataGroup()
{
DataEntries = new List<DataEntry>();
}
public void Add(DataEntry de)
{
// Check stuff here
// ...
//
DataEntries.Add(de);
de.Parent = this;
}
}
it would certainly work, but with one major drawback: DataEntry.Parent has a public setter, so the property could be modified from anywhere without any of the checks I designed in DataGroup.Add()
I could maybe do the following:
public class DataEntry
{
private DataGroup _parent;
public DataGroup Parent
{
get { return _parent; }
set
{
_parent = value;
_parent.Add(this);
}
}
}
public class DataGroup
{
...
public void Add(DataEntry de)
{
// Check stuff here
// ...
//
_dataEntries.Add(de);
// de.Parent = this; Already set!
}
...
}
which would work fine in case I wanted to add the child by setting its parent property, but would not update DataEntry.Parent if I called DataGroup.Add()
As I already said, it is quite normal for WinForms controls not to be able to change the Parent property directly in the child, but the property is changed after the Add method is called from the parent.
I can't figure out the link, a way for the parent to modify a property in the child, unless that property is public or exposed through a method, both of which would grant a chance to bypass my checks and ultimately produce errors.
if you just want to hide the method from outside parties you could declare the method internal
internal void SetParent(DataGroup dg)
{
//code to set parent
}
I've never tried this but it might work also. I do it with private all the time.
public DataGroup Parent { get; internal set; }
Another option to hide it from yourself a little more is to have an Explicit Interface Implementation. and even combine it with internal to hide it from outside. When you Explicitly implement an interface the only way to call the method is to cast the object to the interface first. I think something like this would work
internal interface ISetParent
{
void SetParent(DataGroup dg);
}
public class DataEntry : ISetParent
{
void ISetParent.SetParent(DataGroup dg)
{
Parent = dg;
}
public DataGroup Parent { get; private set;}
}
public class DataGroup
{
public List<DataEntry> DataEntries { get; set; }
public DataGroup()
{
DataEntries = new List<DataEntry>();
}
public void Add(DataEntry de)
{
// Check stuff here
// ...
//
DataEntries.Add(de);
((ISetParent)de).SetParent(this);
}
}
I have two ComboBoxes, A & B, each bound to an Observable Collection. Each has a SelectionChanged trigger is attached which is intended to catch when the user changes a selection. The trigger passes the selection to a Command.
The collections implement INotifyPropertyChanged in that, in the Setter of each, an NotifyPropertyChanged event is fired. This is needed (in the MVVM approach) to notify the UI (the View) that the ComboBox's contents have changed.
The two ComboBoxes are interdependent - changing the selection in A causes B to be repopulated with new items.
Now, the problem is that B's SelectionChanged trigger fires in response to its collection being repopulated (as well as the user changing a selection). Due to the complexity of the code in the Command this is a huge waste of resources.
I could in theory stop this by not raising the NotifyPropertyChanged event when B's collection is set (because, looking at the Call Stack, this is what seems to cause the SelectionChanged trigger to fire), however the MVVM approach depends on this to keep the UI refreshed.
Any suggestions?
Why does ComboB need a SelectionChanged event? You can just bind the selected item directly into a property on the VM.
The way i have tackled this previously was to bind ComboA's selected item into the VM. In the setter for that property, i recalculate the available items for ComboB and assign them to another property on the VM, and ComboB's ItemsSource is bound to this property. Of course that property will notify (using INotifyPropertyChanged), but nothing else needed to be done, my ComboB did not have a SelectionChanged event. By using this method i didn't need a SelectionChanged on ComboA either, which keeps the view's code behind nice and sparse - everything is handled in the VM and regular databinding takes care of the rest.
Edit:
Here is an example of adjusting the required lists from within the property setters:
public class MyViewModel : INotifyPropertyChanged
{
//ItemsSource of ComboA is bound to this list
public List<SomeObject> ComboAList
{
get { return _comboAList; }
set { _comboAList = value; }
}
//ItemsSource of ComboB is bound to this list
public List<SomeObject> ComboBList
{
get { return _comboBList; }
set
{
_comboBList = value;
OnPropertyChanged("ComboBList");
}
}
//ItemsSource of the dataGrid is bound to this list
public List<SomeObject> DataGridList
{
get { return _datagridList; }
set
{
_datagridList = value;
OnPropertyChanged("DataGridList");
}
}
//SelectedItem of ComboA is bound to this property
public SomeObject FirstSelectedItem
{
get { return _firstSelectedItem; }
set
{
_firstSelectedItem = value;
RefreshListForComboB();
}
}
//SelectedItem of ComboB is bound to this property
public SomeObject SecondSelectedItem
{
get { return _secondSelectedItem; }
set
{
_secondSelectedItem = value;
RefreshListForDataGrid();
}
}
private void RefreshListForComboB()
{
//do whatever is necessary to filter or create a list for comboB
ComboBList = doSomethingThatReturnsAListForComboB();
}
private void RefreshListForDataGrid()
{
//do whatever is necessary to filter or create the list for the DataGrid
DataGridList = doSomethingThatReturnsAListForDataGrid();
}
protected void OnPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
#endregion
private List<SomeObject> _comboAList, _comboBList, _datagridList;
private SomeObject _firstSelectedItem, _secondSelectedItem;
}
And here is a slightly different way to do it, using a PropertyChange event handler on the VM, this simply changes where the list updating happens. This is arguably a better way of doing it than the first sample as it means the property setters don't have side effects:
public class MyViewModel : INotifyPropertyChanged
{
public MyViewModel()
{
this.PropertyChanged += new PropertyChangedEventHandler(MyViewModel_PropertyChanged);
}
private void MyViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
switch (e.PropertyName)
{
case "FirstSelectedItem":
RefreshListForComboB();
break;
case "SecondSelectedItem":
RefreshListForDataGrid();
break;
}
}
//ItemsSource of ComboA is bound to this list
public List<SomeObject> ComboAList
{
get { return _comboAList; }
set { _comboAList = value; }
}
//ItemsSource of ComboB is bound to this list
public List<SomeObject> ComboBList
{
get { return _comboBList; }
set
{
_comboBList = value;
OnPropertyChanged("ComboBList");
}
}
//ItemsSource of the dataGrid is bound to this list
public List<SomeObject> DataGridList
{
get { return _datagridList; }
set
{
_datagridList = value;
OnPropertyChanged("DataGridList");
}
}
//SelectedItem of ComboA is bound to this property
public SomeObject FirstSelectedItem
{
get { return _firstSelectedItem; }
set
{
_firstSelectedItem = value;
OnPropertyChanged("FirstSelectedItem");
}
}
//SelectedItem of ComboB is bound to this property
public SomeObject SecondSelectedItem
{
get { return _secondSelectedItem; }
set
{
_secondSelectedItem = value;
OnPropertyChanged("SecondSelectedItem");
}
}
private void RefreshListForComboB()
{
//do whatever is necessary to filter or create a list for comboB
ComboBList = doSomethingThatReturnsAListForComboB();
}
private void RefreshListForDataGrid()
{
//do whatever is necessary to filter or create the list for the DataGrid
DataGridList = doSomethingThatReturnsAListForDataGrid();
}
protected void OnPropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
#endregion
private List<SomeObject> _comboAList, _comboBList, _datagridList;
private SomeObject _firstSelectedItem, _secondSelectedItem;
}
I'm trying to instance an object(s) from xaml. The object's class inherits from a base class. Everything works good except that the a base class property ("Key") is not setting correctly from xaml. It's always null. The object's properties itself are set OK from xaml. Also when I set the Key property from code it sets fine.
I put a breakpoint on the closing bracket of the MainWindow method to view the object data. The hover details tells me the Key property is always null.
Any ideas what I'm doing wrong?
<?xml version="1.0" encoding="utf-8" ?>
<GroupUiItem xmlns="clr-namespace:Configurator.UiCore"
Key="key_grp1" UserName="grp1">
<ParameterUiItem Key="key_par1" UserName="par1"/>
<GroupUiItem Key="key_grp2" UserName="grp2">
<ParameterUiItem Key="key_par2" UserName="par2"/>
<ParameterUiItem Key="key_par3" UserName="par3"/>
</GroupUiItem>
<ParameterUiItem Key="key_par4" UserName="par4"/>
<ParameterUiItem Key="key_par5" UserName="par5"/>
<ParameterUiItem Key="key_par6" UserName="par6"/>
</GroupUiItem>
public partial class MainWindow : Window
{
public MainWindow()
{
GroupUiItem ConfigUi = new GroupUiItem();
InitializeComponent();
using (FileStream stream = new FileStream("XMLFile1.xaml", FileMode.Open, FileAccess.Read))
{
ConfigUi = XamlReader.Load(stream) as GroupUiItem;
}
ConfigUi.Key = "key_grp1"; // this works OK
CategoryList.ItemsSource = ConfigUi.Children;
}
}
// These are in the Configurator.UiCore namespace:
public class ConfiguratorUiItem
{
protected string _Key;
public string Key
{
get { return _Key; }
set { _Key = value; }
}
}
[ContentProperty("Children")]
public class GroupUiItem : ConfiguratorUiItem
{
private ObservableCollection<ConfiguratorUiItem> _Children = new ObservableCollection<ConfiguratorUiItem>();
public ObservableCollection<ConfiguratorUiItem> Children
{ get { return _Children; }
set { _Children = value; }
}
private string _UserName;
public string UserName
{ get { return _UserName; }
set { _UserName = value; }
}
}
public class ParameterUiItem : ConfiguratorUiItem
{
private string _ParameterType;
public string ParameterType
{
get { return _ParameterType; }
set { _ParameterType = value; }
}
private string _UserName;
public string UserName
{
get { return _UserName; }
set { _UserName = value; }
}
}
OK figured out my problem. Noob mistake. Needed to set build action to None and copy always. I had build action set to a page so it wasn't a loose xaml and wasn't updating to appropriate folder. I copied the xaml file to output directory manually when I first couldn't figure out the problem. This caused the program to always use the old file.
When I did this also had to add ";assembly=Configurator" to the end of the xmlns so that it now reads: "xmlns="clr-namespace:Configurator.UiCore;assembly=Configurator". Then it worked.