I'm trying to create my calendar control with databinding.
public partial class Calendar : UserControl
{
public static readonly DependencyProperty DateProperty =
DependencyProperty.Register("Date", typeof(DateTime),
typeof(Calendar), null);
public object Date
{
get { return GetValue(DateProperty); }
set
{
SetValue(DateProperty, value);
OnPropertyChanged("Date");
}
}
public Calendar()
{
// Required to initialize variables
InitializeComponent();
DayText.Text = ((DateTime)Date).ToString("dd");
MonthText.Text = ((DateTime)Date).ToString("MMM");
this.Loaded += new RoutedEventHandler(Calendar_Loaded);
this.GotFocus += new RoutedEventHandler(Calendar_Loaded);
}
void Calendar_Loaded(object sender, RoutedEventArgs e)
{
DayText.Text = ((DateTime)Date).ToString("dd");
MonthText.Text = ((DateTime)Date).ToString("MMM");
}
}
But When I create the listbox with this control, same calndar have the wrong date. I'm sure that the Date passed thorough databinding is correct but I don't understand why same calender show a different day (I'm noticed that is the day of a previous calendar control intance)
Thank you for supporting!
Hmm ... where do we start? Here's a few things I've noticed:
If you're using a dependency property, there's no need to call OnPropertyChanged from the Date property setter.
The dependency property declares the type as DateTime, but your public exposed property is of type object, which then requires you to cast it elsewhere.
If Calendar_Loaded is to be called in more situations than in response to the Loaded event (such as the GotFocus event, then I'd recommend that you call it something else, or create a method with a relevant name (e.g. UpdateDateParts) and call it from properly named separate event handlers.
Using fixed format specifiers when processing date strings does not localize well.
In addition to that, I'd suggest that you could implement the user interface in a manner that supports databinding (and re-templating) by using bindings and exposing the date parts of the Date dependency property instead of manually updating the Text property of some text blocks/boxes in event handlers. In fact, if you derive from Control instead of UserControl then you can create and actuall lookless control that has it's user interface defined by a style in themes\generic.xaml that can be re-defined by users of your control.
As for why the date is incorrect in different instances of your calendar control, we'd need to see some of your XAML/code to see how the control is being used and initialized to be able to provide a better answer. However, I thought the above was worth putting in an Answer, instead of trying to say it in a Comment.
Related
I'm writing a JFace dialog, and I'd like to use databing to a model object.
Looking at code I can see that there are times when I find a PojoProperties used to build the binding, while other time it is used a PojoObservables.
Looking at the Javadoc I can read:
PojoObservables: A factory for creating observable objects for POJOs (plain old java objects) that conform to idea of an object with getters and setters but does not provide property change events on change.
PojoProperties: A factory for creating properties for POJOs (plain old Java objects) that conform to idea of an object with getters and setters but does not provide property change events on change.
The same question applies to the difference that exists between BeansObservables and BeansProperties
The (obvious) difference sems to be that the observable allows to observe objects and the properties allows to observe properties, but since a Pojo has a getter and a setter for its data, what is the difference between them? And which of them should I choose for my dialog?
Here follows a code excerpt:
The POJO:
public class DataObject {
private String m_value;
public String getValue() {
return m_value;
}
public void setValue(String i_value) {
m_value = i_value;
}
}
The DIALOG (relevant part):
#Override
protected Control createDialogArea(Composite parent) {
Composite container = (Composite) super.createDialogArea(parent);
m_combo = new Combo(container, SWT.BORDER);
m_comboViewer = new ComboViewer(container, SWT.NONE);
}
The BINDING (relevant part):
// using PojoObservable
IObservableValue observeValue = PojoObservables.observeValue(m_dataObject, "value");
IObservableValue observeWidget = SWTObservables.observeSelection(m_combo);
// using PojoProperties
IObservableValue observeValue = PojoProperties.value("value").observe(m_dataObject);
IObservableValue observeWidget = ViewerProperties.singleSelection().observe(m_comboViewer);
I understand that one time I'm using a combo and another I'm using a ComboViewer, but I can get the combo from the viewer and bind the other way if I need...
Also, can I mix the two, for example use the observeValue with the ViewerProperties?
IObservableValue observeValue = PojoObservables.observeValue(m_dataObject, "value");
IObservableValue observeWidget = ViewerProperties.singleSelection().observe(m_comboViewer);
I am playing around a little with JFace viewers (especially ComboViewer) & databinding and discovered that if I use
SWTObservables.observeSelection(comboViewer.getCombo());
then databinding is not working correctly.
However, if I use
ViewersObservables.observeSingleSelection(comboViewer);
Then everything is working as expected.
Maybe this is a special for my case, so to get it a better overview I'll describe my set up in following paragraph.
I have modelObject with field named selectedEntity and entities and bind this ComboViewer to the modelObject.
I want to display all "entities" in model object, if I add any entity to the modelObject.entities collection then I want to this entity be added to combo automatically.
If user selects some item in combo I want to modelObject.selectedEntity be set automatically.
If I set modelObject.selectedEntity I want to combo selection be set automatically.
Source code can be found at: https://gist.github.com/3938502
Since Eclipse Mars, PojoObservables is deprecated in favor of PojoProperties and BeansObservables is deprecated in favor of BeanProperties so the answer to which one should be used has now become evident.
I am working on a Silverlight application using V3 SP1 of MVVM Light Toolkit.
My application is fully French/English. All UI elements (buttons, labels, etc.) and all the data (models). I need dynamic language switching and this is fully implemented and works with anything coming from a resource file. What I am struggling with is the ViewModels.
The Models have language specific prperties (DescriptionEn, DescriptionFr) and an additional property call LocalizedDescription which uses the current culture to return call the language specific property.
When the language changes (via a button click) I raise and broadcast (via the Messenger) a property changed event.
In each of my ViewModels, I register to receive the property changed message for the language swap.
I want to notify all the properties of the ViewModel that something has changed.
From: http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.propertychanged.aspx
The PropertyChanged event can indicate all properties on the object have changed by using either null or String.Empty as the property name in the PropertyChangedEventArgs.
However, since the toolkit abstracts the raising of the changed event with RaisePropertyChanged(...) I cannot get this to work. I have also examined the source of the tookit and discovered that RaisePropertyChanged calls VerifyPropertyName(..) which in turn returns an error is the property does not belong to the ViewModel. I also noticed that the VerifyPropertyName method is attributed with Conditional("DEBUG"), but even if I choose the Release configuration, the ArgumentException("Property not found") is still raised.
Does anyone know of a way to get this to work using the toolkit aside from manually calling RaisePropertyChanged for every property of the ViewModel?
Follow-up:
Based on the comment from Simon, I attempted to create my own class that extends ViewModelBase. I looked at the source on CodePlex and decided to create a single method called RaiseAllPropertyChanged(). It would simply be a copy of the RaisePropertyChanged(string propertyName) but without the parameter and without the call to VerifyPropertyName(...). I cannot get it to work. Here is what I have.
public class ViewModelBaseExtended : ViewModelBase
{
protected void RaiseAllPropertyChanged()
{
var handler = this.PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(String.Empty));
}
}
}
But I get a compiler error: The event 'GalaSoft.MvvmLight.ViewModelBase.PropertyChanged' can only appear on the left hand side of += or -=. This is a copy of the code that is used in the ViewModelBase.
Can someone offer some advice as to how to get this to work?
Solution:
I copied all the code from ViewModelBase into a new class. I then added the method RaisePropertyChanged() mentioned above which instantiates the PropertyChangedEventArgs class with String.Empty. This is now the new subclass for my ViewModels.
Thanks again to Simon for leading the way!
In case you're reading this in 2016, you can use ObservableObject and notify that all of the properties have changed by doing:
RaisePropertyChanged(string.Empty);
Unfortunately this is not possible with the current code-base of MVVMLight
In the short term your have 2 options:
User your own custom base class. And by custom base class I mean "Do not inherit from the MVVMLight class".
Download and compile MVVMLight in Release mode. This will force the "VerifyPropertyName" method to be excluded. Of course then you don't get the value of property name checks.
I am sure Laurent Bugnion will have this fixed soon.
A lighter solution to this problem would have been to override RaisePropertyChanged(string propertyName) in your class :
protected override void RaisePropertyChanged(string propertyName)
{
if (propertyName != null)
{
base.RaisePropertyChanged(propertyName);
}
else
{
var handler = PropertyChangedHandler;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(null));
}
}
}
I am using a DataRepeater to show data from a business objects on the screen. I am using windows forms in C# to accomplish this. The datasource is not available at compile time so I want to bind the datasource at runtime.
Here is the simplified scenario. I'm using this business class:
public class Product
{
private double _price;
public double Price
{
get
{
return _price;
}
set
{
_price = value;
}
}
}
I have created a ProductDataSource with the VisualStudio interface and bound the price to a label. Now I filled the datasource of my repeater in code:
dataRepeater1.DataSource = _productDataAgent.GetProducts();
When I startup my application the prices are correctly filled in the labels. So far so good.
Now I want the price labels to be updated when the product is updated. The Visual Studio interface helps me, and let me choose a 'Data Source Update Mode'. So I choose "OnPropertyChanged".
Here comes the tricky part. How does the .NET runtime know that the price property is updated from the backend. So I modify my business class to implement INotifyPropertyChanged. Like this:
public class Product : INotifyPropertyChanged
{
private double _price;
public double Price
{
get
{
return _price;
}
set
{
_price = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("Price"));
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
The problem is this doesn't work. When I update a product it remeanes un-updated in the interface. When I debug and change the property, I see that the PropertyChanged event is null so no one is listening.
Delving a little deeper in to the problem I found the following on the System.Windows.Forms.Binding Constructor page on MSDN:
An event named PropertyNameChanged.
So I tried using a (custom) PriceChanged event, but that did not work.
Am I doing something wrong here? I am comming from using WPF, so maybe this works a little different in Windows Forms? Is this because I am binding at runtime?
Jep found the sollution. Apparently you cannot simply bind to a list of products. You will see the products initially, but they will not be updated when a property is changed. Instead you need to statically bind to a BindingSource. Just create an object datasource using the Visual Studio (in the data menu). Code like this is generated:
private System.Windows.Forms.BindingSource beursProductDisplayBindingSource;
this.beursProductDisplayBindingSource = new System.Windows.Forms.BindingSource(this.components);
this.dataRepeater1.DataSource = this.beursProductDisplayBindingSource;
Now you can dynamically bind like this:
BindingSource productBinding = ((BindingSource)dataRepeater1.DataSource);
_productDataAgent.BeursProducts.ForEach(product => productBinding.Add(product));
Now when implementing INotifyPropertyChanged in your data object like I did is works like expected. Just forgot one step which is not needed when using WPF.
I'm not clear about this....
When having a gridview on the View, is the controller who has to set up the Data source, columns, etc? or I just have to expose the DataBinding stuff, fire it from the controller and let the html/codebehind on the view handle all the rendering and wiring up?
To be more precise: on the view should I have
private GridView _gv
public _IList<Poco> Source {
get {_gv.DataSource;}
set {_gv.DataSource = value;
_gv.DataBind();}
}
Or should it be (from MVP pattern - Passive View and exposing complex types through IView (Asp.Net, Web Forms))
private GridView _datasource;
public DataSource
{
get { return _datasource; }
set
{
_datasource = value;
_datasource.DataBind();
}
}
Maybe I'm having it all wrong ....
Where can I find an example that is not a "Hello world" example on MVP for ASP.Net???
Your controller should be in charge of setting the "result" of the databinding. The view is in charge of displaying it propertly.
So for example, your webform/usercontrol (View) could have the data source exposed as an object property that your View should know how to handle when it receives it:
public MyObject DataSource
{
set
{
_datasource = value;
_datasource.DataBind();
}
}
So if you need to have an ItemDataBound event, I would still handle it in the view. Even though there could be business logic in the event. If you need to have business logic in the event, I would put it in the MyObject result before it is passed to the view.
So an example would be to have a property of "MyObject" be "AllowDelete" and in your ItemDataBound, the value of this property determines if a column in the GridView is enabled or not.
Having just listened to a recent Hanselminutes on this topic, it might be worth having a look at the http://webformsmvp.com/ project, which seems to bring a bit of rigidity into separating concerns within WebForms.
I have a question regarding a data binding(of multiple properties) for custom DataGridViewColumn.
Here is a schema of what controls that I have, and I need to make it bindable with DataGridView datasource. Any ideas or a link to an article discussing the matter?
Controls
Graph Control(custom): Displayed in
the custrom DataGridView column. Has
properties like "Start Date",
"EndDate", Windows Chart control,
which is itself, bindable, etc.
Custom cell(DataGridViewCustomCell inherits
from DataGridViewCell) that holds
the Graph control and processes some
events(OnEnter event, for example,
passes the focus to the custom Graph
column for drag-n-drop type of
events, etc.)
Custom column(DataGridViewCustomColumn
inherits from DataGridViewColumn)
that defined the cell template type:
CellTemplate = new
DataGridViewCustomCell(); and also a
primary choice for data binding
Data Structure:
Main table to be displayed in other DataGridView Columns
Graph table - related to the Main table via parent-child relationship. Holds graph data
Chart table related to the graph table via parent-child relationship. Holds data for the win-form chart, which is a part of my Graph control.
So far I cannot even bind data from the Graph table to by Graph control or Graph-holding Column/Cell.
Thank you for your answer. My data sources is not a SQL data source, and as a matter of fact I was talking about datagridview for win-forms(I'm not sure that was clear).
As I did not get the reply on any of the forums I was asking the question, I figured, I would outline a solution I came up with, for those who may have a similar problem and for possible critique. :-)
(steps 1-2 are also explained in the famous MS example)
1. Create your own classes that inherit from DataGridViewColumn and DataGridViewCell, setup the column template;
2. Create your "CustomEdit" control
In the data item, whatever that is, a DataRow, or a List item, add a read-only property, that return the object itself. This property is bound to the custom column.
Custom Cell:
public partial class MyCell : DataGridViewCell
{
protected override void Paint(...)
{...} // draws control
// receives data item as a value
// in my case I have to custom-draw entire control in this fnc.
public override void InitializeEditingControl(...)
{...} // initialize control editing
// override some other properties
public override Type EditType {
get{
return typeof(MyEditControl);
}
}
public override Type ValueType{
get{
return typeof(MyItem);
}
}
}
Custom Column:
public partial class MyColumn : DataGridViewColumn
{
public MyColumn(){ ...
CellTemplate = new MyCell();
}
}
Edit Control:
public partial class MyEditControl : UserControl, IDataGridViewEditingControl
{... // implements IDataGridViewEditingControl
// value is our data item
}
Data Item, the data sources becomes List<MyItem>
public class MyItem:Object{
...
[XmlIgnore] // I need it because I do serialization
public MyItem Self {
get {
return this;
}
}
}
See my question Here
It's easy to do, you just don't use the IDE to do it, you do it all in code. It's a lot of work, but it's not that difficult if you know what your doing. I went from knowing nothing to being able to do it in less than a day so I'm sure you'll be able to do it.
Edit: you can also use a Join in the sql that populates the datagridview