ComboBox in MVVM light not displaying List<string> items - wpf

This has me stumped - hopefully someone can point out an obvious error. I have a user control that I am adding to a grid in the MainView of my program. Main view is bound to MainViewModel and the usercontrol is bound to CardioVM.
I have used a test label to check that the routing of the user control is correct and all work ok. I have a class named Cardio which has a property of
List<string> exercises
I am trying to pass the strings in
Cardio.List<string> exercises
to a
List<string> CardioList
in my CardioVM. When debugging
List<string> CardioList
is getting populated with items from
Cardio.List<string> exercises
but my ComboBox is not displaying the items on screen. Here is xaml for my UserControl and :
<UserControl x:Class="CalendarTest.UserControl1"
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="300"
DataContext="{Binding CardioVM, Source={StaticResource Locator}}">
<Grid>
<ComboBox ItemsSource="{Binding CardioList, Mode=OneWay}" SelectedItem="{Binding SelectedCardio, Mode=TwoWay}" Height="50"></ComboBox>
</Grid>
and here is the code for my CardioVM:
public class CardioVM : ViewModelBase
{
public Cardio cardioItem { get; set; }
public CardioVM()
{
TestLabel = "Tester";
}
//Test Label for binding testing
private string testLabel;
public string TestLabel
{
get { return testLabel; }
set
{
testLabel = value;
RaisePropertyChanged("TestLabel");
}
}
public CardioVM(string Date, string File)
{
cardioItem = new Cardio(File, Date);
CardioList = new List<string>(cardioItem.exercises);
}
private List<string> cardioList;
public List<string> CardioList
{
get { return cardioList; }
set
{
cardioList = value;
RaisePropertyChanged("CardioList");
}
}
private string _selectedCardio;
public string SelectedCardio
{
get { return _selectedCardio; }
set
{
_selectedCardio = value;
RaisePropertyChanged("SelectedCardio");
}
}
}
}
Not sure where I am going wrong here but any pointers would be much appreciated.
Here is where I thought I was adding in the userControl to a content control bound proprty in my Main view model:
public void NewTemplateExecute()
{
TextHideTab = "Close";
NewTemplateType = ("New " + SelectedExercise + " Exercise Template");
//Set the message and lists based on the exercise selected plus adds the drop down control
switch (SelectedExercise)
{
case "Cardio":
///
//This is where I thought CardioVM was being added
///
NewTemplateText = "Please choose a cardio exercise from the drop down list to the left. You can then select the duration of the exercise and the intensity. To add another exercise please press the plus button in the right hand corner";
ExerciseDropDowns = new CardioVM(selectedDateLabel, #"Model\Repository\Local Data\CardioList.txt");
break;
case "Weights":
NewTemplateText = "Please select a exercise type. you can refine your exercises by body area. Then add the number of sets and the reps per set. Add as many exercises as you like - dont forget to set to total duration";
break;
case "HIIT":
NewTemplateText = "HIIT to add";
break;
}
Messenger.Default.Send("NewTemplate");
}
I had set the datacontext for CardioVM in my Mainwindow xaml as:
<DataTemplate DataType="{x:Type local:CardioVM}">
<view:UserControl1/>
</DataTemplate>
I presume I have made a mistake in the way that I have hooked up CaridoVM but couldn't seem to get it to databind unless I sent it through the VM locator

Thanks to nemesv - you were of course spot on. Removed the DataContext from my CardioVM and now just using DataTemplate set in Main view to bind the Cardio view to the ViewModel. I can now call a cardioVM with parameters from the Mainview and it populates my combobox as expected. Seems I nbeeded to touch up on some of the basics of MVVM

Related

WPF: What is more easy is convinient to develop dynamically?

I have a DataGrid (dataGrid1) where records can be added and deleted.
Based on that dataGrid1, I want to make a new Grid with buttons in it based on ID and Types'. Cols will also have to given a DataSource of add dynamically, but that will be just while generating for the 1st time in Window_Loaded itself. Rows can be added/removed based on changes in dataGrid1. I want somethign like this :
On each Btn click, a new window will be opened for entry of the particular Type and for the particular ID. If the details are already entered, then the text of btn wil be "Update" else "Add".
What could be the best resource/control to perform this operations ? At present, I just did a Grid with 2 stable cols. Any ideas for the above to use Grid, DataGrid or something else. And adding/removing rows will be easy in which way and how.
Any help is appreciated.
Okay, let me try to take an example which is similar to your needs
Let's assume we use this class:
public class MyObject
{
public int MyID;
public string MyString;
public ICommand MyCommand;
}
And we are willing to display a DataGrid listing the ID, and having as a second column a Button, with the property MyString as content, which, when clicked, launches the ICommand MyCommand which opens in a new window whatever you want.
Here is what you should have on the View side:
<DataGrid ItemsSource="{Binding MyList}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Header="ID" Binding="{Binding MyID}" />
<DataGridTemplateColumn Header="Buttons">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Content="{Binding MyString}" Command="{Binding MyCommand}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
This will show a DataGrid taking all the content in an IEnumerable<MyObject> named 'MyList', and shows two columns as defined before.
Now if you need to define the command.
First, I recommend you read this introductory link to MVVM and take the RelayCommand class (that's what we're gonna use for your problem)
So, in your ViewModel, the one which defines the MyList, here is how you should define some of the useful objects:
public ObservableCollection<MyObject> MyList { get; set; }
// blah blah blah
public void InitializeMyList()
{
MyList = new ObservableCollection<MyObject>();
for (int i = 0; i < 5; i++)
{
MyList.Add(InitializeMyObject(i));
}
}
public MyObject InitializeMyObject(int i)
{
MyObject theObject = new MyObject();
theObject.MyID = i;
theObject.MyString = "The object " + i;
theObject.MyCommand = new RelayCommand(param =< this.ShowWindow(i));
return theObject
}
private void ShowWindow(int i)
{
// Just as an exammple, here I just show a MessageBox
MessageBox.Show("You clicked on object " + i + "!!!");
}
This should be enough to create whatever you want. As you can see, every Button will call a method (ShowWindow) which is defined to show your new window, do whatever you need inside. The RelayCommand is actually just here, as its name says, to relay the command fired by the button to a method which contains the execution logic.
And... I think that's all you need. Sorry for the late answer BTW
EDIT - generating columns manually/dynamically
The following code is part of a code I had to do when I had a similar problem.
My problem was, I needed to change the columns displayed every time a ComboBox's SelectedItem would change. So I put this in a SelectionChanged event handler.
I don't know where exactly do you need to generate your columns, but I'll give you a general example.
Assume your ItemsSource is an ObservableCollection<MyNewObject>
MyNewObject is the following:
public class MyNewObject
{
public IList<string> MyStrings { get; set; }
}
You should put somewhere in your code (should be when you need to generate the column) the following code, which is generating a number of columns equal to the length of the first MyNewObject from the list (note: this is in code-behind, and the DataGrid you're working on is named dataGrid)
ObservableCollection<MyNewObject> source = dataGrid.ItemsSource as ObservableCollection<MyNewObject>;
if (source == null || source.Count == 0)
{
return;
}
MyNewObject firstObject = source[0];
for(int i = 0; i < firstObject.MyStrings.Count; i++)
{
// Creates one column filled with buttons for each string
DataGridTemplateColumn columnToAdd = new DataGridTemplateColumn();
columnToAdd.Width = 110; // I set a manual width, but you can do whatever you want
columnToAdd.Header = "Header number " + i;
// Create the template with a Button inside, bound to the appropriate string
DataTemplate dataTemplate = new DataTemplate(typeof(Button));
FrameworkElementFactory buttonElement = new FrameworkElementFactory(typeof(Button));
Binding binding = new Binding("MyStrings[" + i + "]");
binding.Mode = BindingMode.TwoWay;
binding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
buttonElement.SetBinding(Button.ContentProperty, binding);
// Do the same here for your command, or for whatever you want to do when the user clicks on this button
dataTemplate.VisualTree = buttonElement;
columnToAdd.CellTemplate = dataTemplate;
dataGrid.Columns.Add(columnToAdd);
}
This will create one column for each string found in the first object. Then, enhance it with whatever command or display trick you need!

A collection of StackPanel as ItemsSource of ComboBox

I have
a collection of StackPanel which each one includes a dynamic set of controls (based on database values), I want to set them as ItemsSource of some ComboBox
for example i have two database values which should be generated:
In DB i have these:
row 1=>Class [a] p [B] , [AB]vb
row 2=>Class tpy rbs=[sdfg],kssc[h] hm
and each one should generate as a ComboBox column like the fallowing:
In ComboBox I wanna generate these :
ComboBoxItem 1 :Class [a textBox] p [a textBox] , [a textBox]vb
ComboBoxItem 2 :Class tpy rbs=[a textBox].kssc[a textBox] hm
the fallowing code is doing this right:
Class ConvertToControlsFormat()
{
Regex exp = new Regex(#"\[\w*\]");
var source = new TestEntities().cmbSources;
foreach (var item in source)
{
StackPanel p = new StackPanel { Orientation = Orientation.Horizontal, FlowDirection = FlowDirection.LeftToRight };
int i = 0;
foreach (string txt in exp.Split(item.Title))
{
p.Children.Add(new TextBlock { Text = txt });
if (i < exp.Matches(item.Title).Count)
p.Children.Add(new TextBox { Text = exp.Matches(item.Title)[i].Value, Width = 30 });
}
cmb.Items.Add(p);
}
}
But I cant set TwoWay DataBindings for that, so I created a list of StackPanel as a field of cmbSource class (which is bound to ItemsSource of the ComboBox)
public partial class cmbSource
{
#region Primitive Properties
int iD;
public virtual int ID
{
get
{
if (Title != null)
ControlsCollection = SetControlsCollection(Title);
return iD;
}
set
{
iD = value;
}
}
private StackPanel SetControlsCollection(string ttl)
{
Regex exp = new Regex(#"\[\w*\]");
StackPanel p = new StackPanel { Orientation = Orientation.Horizontal, FlowDirection = System.Windows.FlowDirection.LeftToRight };
int i = 0;
foreach (string txt in exp.Split(ttl))
{
p.Children.Add(new TextBlock { Text = txt });
if (i < exp.Matches(ttl).Count)
p.Children.Add(new TextBox { Text = exp.Matches(ttl)[i].Value, Width = 30 });
}
return p;
}
public virtual string Title
{
get;
set;
}
public virtual StackPanel ControlsCollection
{
get;
set;
}
#endregion
}
but I have no idea of how bind it to ItemsSource of my ComboBox
Summery:I want to bind a list of controls to a ComboBox
any suggestions!? thank you.
EDIT
First: you do not bind a ComboBox to a collection of UI Elements. That is not the way WPF works. Container controls such as the Grid, StackPanel and Canvas can contain child controls. ItemsControls such as the ComboBox contain data objects and use DataTemplates to display the items.
Secondly: if the database can contain ANY data that could cause ANY UI to be needed you will need to generate the UI in code by creating StackPanels etc. adding controls and bindings as you do in your code examples.
Thirdly: the reason you can't bind is that the data from the database is a string that you split into parts; there is no way you can simply go back to the string.
Suggestion: the string in the database is probably (I hope) in some sort of format. Using that knowledge you could generate a new format string when you are parsing the database string. E.g., when the database contains foo [bar] you could generate {0} [bar]. On a save action from the user you could use that string to create the updated string for the database by using: String.Format("{0} [bar]", someControl.Text)
Extra: Please, next time, use better names and example texts; the question is unreadable like this. There is no way you can expect us to understand 2=>Class tpy rbs=[sdfg],kssc[h] hm
OLD ANSWER
Make a class Stuff, implementing INotifyPropertyChanged and having the properties Name and Value.
Load the database data into an ObservableCollection<Stuff> and bind the ComboBox to this collection.
Set the ItemTemplate of the combo box to a datatemplate like this:
<ComboBox ItemsSource="{Binding}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}"/>
<TextBox Text="{Binding Value}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>

WPF Databinding to generic List<>

I am doing something wrong .. you know how it is.
I have tried playing around with ItemsSource , DataContext , DisplayMemberPath and SelectedValuePath and I either get a blank list of a list of the ToString method being called in the Person object;
WHAT WOULD REALLY HELP is for someone to publish an answer that works for this example.
I have simplified the problem as I am having difficulty in general with databinding generics.
I have created a simple Generic List of Person and want to bind it to a combo. (also want to try use a ListView too).
I either get a list of blanks or a list of 'xxxx.Person' where xxxx = namespace
<Window x:Class="BindingGenerics.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="300" Width="300">
<Grid>
<ComboBox Name="ComboBox1"
ItemsSource="{Binding}"
Height="50"
DisplayMemberPath="Name"
SelectedValuePath="ID"
FontSize="14"
VerticalAlignment="Top">
</ComboBox>
</Grid>
</Window>
using System.Windows;
using System.ComponentModel;
namespace BindingGenerics
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
Person p = new Person();
// I have tried List and BindingList
//List<Person> list = new List<Person>();
BindingList<Person> list = new BindingList<Person>();
p.Name = "aaaa";
p.ID = "1111";
list.Add(p);
p = new Person();
p.Name = "bbbb";
p.ID = "2222";
list.Add(p);
p = new Person();
p.Name = "cccc";
p.ID = "3333";
list.Add(p);
p = new Person();
p.Name = "dddd";
p.ID = "4444";
list.Add(p);
ComboBox1.DataContext = list;
}
}
public struct Person
{
public string Name;
public string ID;
}
}
In your code sample, Person.Name is a field rather than a property. WPF data binding considers only properties, not fields, so you need to change Person.Name to be a property.
Change your Person declaration to:
public class Person
{
public string Name { get; set; }
public string ID { get; set; }
}
(For production code, you'll probably want to use an ObservableCollection<Person> rather than a List<Person> and either make Person immutable or make it implement INotifyPropertyChanged -- but those aren't the sources of your immediate problem.)
In the code shown you're setting ItemsSource twice, the first time in XAML (called by InitializeComponent) to the DataContext of ComboBox1, which can't be determined from what you've posted but it's probably not what you want. After that you're resetting it from code to your list object (here with typos). In this code you're also adding the same instance of Person 4 times and just changing its Name and ID over and over. I suspect a combination of these issues and the fact that you're using a List instead of ObservableCollection are causing the issues in your application.
It would help narrow it down if you could post some actual code you're seeing problems with as what you've put here isn't even compilable.
Well... I'm assuming your actual code has corrected syntax, as the code you pasted in won't compile.
I put this code into a new WPF app and, after new-ing each Person object, my combobox populated fine. You might want to move your population code into a Loaded event, which will ensure the form is properly constructed. Here's the corrected xaml and codebehind (with a few syntax shortcuts):
xaml:
<Grid>
<ComboBox Name="ComboBox1" Height="70"
DisplayMemberPath="Name"
SelectedValuePath="ID" />
</Grid>
codebehind:
public Window1()
{
InitializeComponent();
this.Loaded += new RoutedEventHandler(Window1_Loaded);
}
void Window1_Loaded(object sender, RoutedEventArgs e)
{
var list = new List<Person>();
Person p = new Person(){Name = "aaaa",ID = "1111"};
list.Add(p);
p = new Person(){Name = "bbbb", ID="2222"};
list.Add(p);
p = new Person(){Name = "cccc", ID="3333"};
list.Add(p);
p = new Person(){Name = "dddd", ID="4444"};
list.Add(p);
ComboBox1.ItemsSource = list;
}

wpf toolkit, datagrid, comboboxcolumn

In a datagrid I have two DataGridComboBoxColumns. The items of one of these columns should depend on what is selected in the other column. The underlying collection used to model this is a dictionary<string,List<string>>. How should i go about implementing this? I can't seem to hook up to any relevant events on the columns, and I cant find any databinding scenarios that support this..
I had the same scenario a while back and fixed it like this:
public class DataItem : INotifyPropertyChanged {
...
public List<SomeObject> DisplayableComboBoxItems {
get; set;
}
private static Dictionary<int, List<SomeObject>> myDict;
public Dictionary<int, List<SomeObject>> MyDict {
get {
if (myDict == null) {
myDict = GetYourDataFromSomewhere();
}
return myDict;
}
}
public int TypeId {
get { return typeId; }
set {
if (value == typeId) return;
typeId = value;
RaisePropertyChanged("TypeId");
}
}
public int TypeSetId {
get { return typeSetId; }
set {
if (typeSetId == value) return;
typeSetId = value;
RaisePropertyChanged("TypeSetId");
DisplayableComboBoxItems = MyDict[typeSetId];
RaisePropertyChanged("DisplayableComboBoxItems");
TypeId = 0;
}
}
...
}
DataItem is the object that gets bound to a DataRow.
This is just a small mock-up of the code. Basically, whenever the TypeSet changes, I needed a new list of Types to be displayed. I used just a static list, in this example i used a dictionary.
With this setup you can bind you combobox ItemsSource to the 'DisplayableComboBoxItems', and your SelectedValue to "TypeId".
You're gonna need other properties to display the correct text instead of the TypeId.
The downside of this is that when you have 1000+ items, you'll have that same list for all items. This wasn't however the case with me (DataGrid showed max 50 items).
I hope this is clear enough and that it helps you in the right direction!
cheers!
Roel
Instead of using a DataGridComboBoxColumn for the second column, I went with a DataGridTemplateColumn with an embedded Combobox. For the itemsource i defined a converter: string -> List<string>. The converter translates the value of the selecteditem of the other DataGridComboBox (which is bound to Navn) into List<string>, this is just a dictionary lookup.
Like so:
<my:DataGridTemplateColumn>
<my:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox SelectedItem="{Binding Værdi}"
ItemsSource="{Binding Navn, Converter={StaticResource dimensionToValues}}"
>
</ComboBox>
</DataTemplate>
</my:DataGridTemplateColumn.CellTemplate>
</my:DataGridTemplateColumn>

WPF ComboBox binding behaviour

I have the following XAML markup:
<TextBox x:Name="MyTextBox" Text="{Binding Path=SelectedCustomer.FavouriteProduct.ProductNumber, UpdateSourceTrigger=PropertyChanged}" />
<ComboBox x:Name="MyComboBox" ItemsSource="{Binding Products}" DisplayMemberPath="ProductName"
SelectedValue="{Binding Path=SelectedCustomer.FavouriteProduct.ProductNumber}"
SelectedValuePath="ProductNumber" />
My View's DataContext is bound to a viewmodel containing a public property called SelectedCustomer. Customer objects contain a FavouriteProduct property of type Product and Product objects contain public properties ProductNumber and ProductName.
The behaviour I'm looking for is to have the SelectedItem of the ComboBox update the Text in the TextBox and vice versa. ComboBox to TextBox works just fine. Selecting any product in the ComboBox updates the TextBox with the product number of that product. However when I try to go the other way I get som strange behaviour. It only works for the items that come before the selected item. I will try to explain:
Consider the following list of products ([Product Number], [Product Name]):
Fanta
Pepsi
Coca Cola
Sprite
Water
Now lets say that the SelectedCustomer's favourite product is Coca Cola (must be a developer). So when the window opens the TextBox reads 3 and the ComboBox reads Coca Cola. Lovely. Now lets change the product number in the TextBox to 2. The ComboBox updates it's value to Pepsi. Now try to change the product number in the TextBox to anything higher then the number for Coca Cola (3). Not so lovely. Selecting either 4 (Sprite) or 5 (Water) makes the ComboBox revert back to Coca Cola. So the behaviour seems to be that anything below the item that you open the window width from the list in the ItemSource does not work. Set it to 1 (Fanta) and none of the others work. Set it to 5 (Water) and they all work. Could this have to do with some initialisation for the ComboBox? Potential bug? Curious if anyone else have seen this behaviour.
UPDATE:
After reading Mike Brown's response I have created properties for SelectedProduct and SelectedProductNumber. The problem I am having with this is that as soon as you select something from the ComboBox you end up in an endless loop where the properties keep updatign each other. Have I implemented the OnPropertyChanged handler incorrectly or is there something I am missing? Here is a snippet of code from my ViewModel:
private int _SelectedProductNumber = -1;
public int SelectedProductNumber
{
get
{
if (_SelectedProductNumber == -1 && SelectedCustomer.Product != null)
_SelectedProductNumber = SelectedCustomer.Product.ProductNumber;
return _SelectedProductNumber;
}
set
{
_SelectedProductNumber = value;
OnPropertyChanged("SelectedProductNumber");
_SelectedProduct = ProductList.FirstOrDefault(s => s.ProductNumber == value);
}
}
private Product _SelectedProduct;
public Product SelectedProduct
{
get
{
if (_SelectedProduct == null)
_SelectedProduct = SelectedCustomer.Product;
return _SelectedProduct;
}
set
{
_SelectedProduct = value;
OnPropertyChanged("SelectedProduct");
_SelectedProductNumber = value.ProductNumber;
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string property)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
UPDATE 2
I have changed the implementation slightly now by updating the SelectedCustomer.FavouriteProduct from both properties and then using that when reading their values. This now works but I'm not sure it's the 'correct way'.
private int _SelectedProductNumber = 0;
public int SelectedProductNumber
{
get
{
if (SelectedCustomer.Product != null)
_SelectedProductNumber = SelectedCustomer.Product.ProductNumber;
return _SelectedProductNumber;
}
set
{
_SelectedProductNumber = value;
SelectedCustomer.FavouriteProduct = ProductList.FirstOrDefault(s => s.ProductNumber == value);
OnPropertyChanged("SelectedProductNumber");
OnPropertyChanged("SelectedProduct");
}
}
private Product _SelectedProduct;
public Product SelectedProduct
{
get
{
if (SelectedCustomer.Product != null)
_SelectedProduct = SelectedCustomer.Product;
return _SelectedProduct;
}
set
{
_SelectedProduct = value;
SelectedCustomer.FavouriteProduct = value;
OnPropertyChanged("SelectedProduct");
OnPropertyChanged("SelectedProductNumber");
}
}
Your aim is not too clear so I have written the folloiwng so support either options I can see.
To keep two elements bound to one item in sync you can set the IsSynchronizedWithCurrentItem="True" on your combobox as shown below:
<TextBox x:Name="MyTextBox" Text="{Binding Path=SelectedCustomer.FavouriteProduct.ProductNumber, UpdateSourceTrigger=PropertyChanged}" />
<ComboBox x:Name="MyComboBox" ItemsSource="{Binding Products}" DisplayMemberPath="ProductName"
SelectedValue="{Binding Path=SelectedCustomer.FavouriteProduct.ProductNumber}"
IsSynchronizedWithCurrentItem="True"
SelectedValuePath="ProductNumber" />
This will mean everything in the current window bound to the same background object will keep in sync and not give the odd behaviours you are seeing.
This quote form this longer MSDN article describes the effect:
The IsSynchronizedWithCurrentItem
attribute is important in that, when
the selection changes, that is what
changes the "current item" as far as
the window is concerned. This tells
the WPF engine that this object is
going to be used to change the current
item. Without this attribute, the
current item in the DataContext won't
change, and therefore your text boxes
will assume that it is still on the
first item in the list.
Then setting the Mode=TwoWay as suggested by the other answer will only ensure that both when you update the textbox the underlying object will be updated and when you update the object the textbox is updated.
This makes the textbox edit the selected items text and not select the item in the combolist with the matching text (which is the alternative think you are may be trying to achieve?)
To achieve the synchronised selection effect it may be worth setting IsEditable="True" on the combobox to allow users to type items in and dropping the text box. Alternatively if you need two boxes replace the textbox with a second combobox with IsSynchronizedWithCurrentItem="True" and IsEditable="True" then a styled to make it like a text box.
What you want to do is expose separate properties on your ViewModel for the currently selected product and currently selected product number. When the selected product is changed, update the product number and vice versa. So your viewmodel should look something like this
public class MyViewModel:INotifyPropertyChanged
{
private Product _SelectedProduct;
public Product SelectedProduct
{
get { return _SelectedProduct; }
set
{
_SelectedProduct = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedProduct"));
_SelectedProductID = _SelectedProduct.ID;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedProductID"));
}
}
private int _SelectedProductID;
public int SelectedProductID
{
get { return _SelectedProductID; }
set
{
_SelectedProductID = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedProductID"));
_SelectedProduct = _AvailableProducts.FirstOrDefault(p => p.ID == value);
PropertyChanged(this,new PropertyChangedEventArgs("SelectedProduct"));
}
}
private IEnumerable<Product> _AvailableProducts = GetAvailableProducts();
private static IEnumerable<Product> GetAvailableProducts()
{
return new List<Product>
{
new Product{ID=1, ProductName = "Coke"},
new Product{ID = 2, ProductName="Sprite"},
new Product{ID = 3, ProductName = "Vault"},
new Product{ID=4, ProductName = "Barq's"}
};
}
public IEnumerable<Product> AvailableProducts
{
get { return _AvailableProducts; }
}
private Customer _SelectedCustomer;
public Customer SelectedCustomer
{
get { return _SelectedCustomer; }
set
{
_SelectedCustomer = value;
PropertyChanged(this, new PropertyChangedEventArgs("SelectedCustomer"));
SelectedProduct = value.FavoriteProduct;
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
So now your XAML binds to the appropriate properties and the viewModel is responsible for syncrhronization
<TextBox
x:Name="MyTextBox"
Text="{Binding Path=SelectedProductID, UpdateSourceTrigger=PropertyChanged}" />
<ComboBox
x:Name="MyComboBox"
ItemsSource="{Binding AvailableProducts}"
DisplayMemberPath="ProductName"
SelectedItem="{Binding SelectedProduct}" />
Don't forget to implement the rest of INotifyPropertyChanged and the GetAvailableProducts function. Also there may be some errors. I hand typed this here instead of using VS but you should get the general idea.
Try:
SelectedItem="{Binding Path=YourPath, Mode=TwoWay"}
instead of setting SelectedValue and SelectedValuePath.
Might work with SelectedValue too, don't forget the Mode=TwoWay, since this isn't the default.
A good approuch would to use the master detail pattern - bind the master (the items view, e.g. combobox) to the data source collection and the detail view (e.g. text box) to the selected item in the source collection, using a binding converter to read/write the appropriate property.
Here is an example:
http://blogs.microsoft.co.il/blogs/tomershamam/archive/2008/03/28/63397.aspx
Notice the master binding is of the form {Binding} or {Binding SourceCollection} and the details binding is of the form {Binding } or {Binding SourceCollection}.
To get this working you need to wrap you collection with an object that keeps the selected item. WPF has one of these built-in: ObjectDataProvider.
Example:
http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/068977c9-95a8-4b4a-9d38-b0cc36d06446

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