WPF Datagrid binding to list problems
I have a list of custom objects: say Fruits with two string properties Name and Color. These are in a List.
private readonly List<Fruit> fruitList = new List<Fruit>();
Then I load fruit objects into the list.
I am trying to bind this list to WPF Datagrid:
C#:
dgFruit.ItemsSource = "{Binding}";
XAML:
<toolkit:DataGrid Name="dgFruit"
ItemsSource="{Binding Path=fruitList}" >
<toolkit:DataGrid.Columns>
<toolkit:DataGridComboBoxColumn
Header="Name"
SelectedValueBinding="{Binding Path=Name}"
TextBinding="{Binding Path=Name}" Width="5*" />
<toolkit:DataGridComboBoxColumn
Header="Color"
SelectedValueBinding="{Binding Path=Color}"
TextBinding="{Binding Path=Color}" Width="5*" />
</toolkit:DataGrid.Columns>
</toolkit:DataGrid>
Reason they are in a combobox is because I want user to be able to change the relationship. This is not the real example but you get the idea. Say for the sake of the example the fruit wasn't ripe so they change Banana color to green :)
I'm not having any luck getting these items in the datagrid... and down the track, I want a click on the item in the datagridcell to change to combobox and show all possible types of Fruit Names and Colors (so they can change the relationships)
Here is an error i'm getting:
System.Windows.Data Error: 39 : BindingExpression path error: 'Color' property not found on 'object' ''Char' (HashCode=6750311)'. BindingExpression:Path=Color; DataItem='Char' (HashCode=6750311); target element is 'TextBlockComboBox' (Name=''); target property is 'Text' (type 'String')
Can anyone help? The reason i am setting my colums up in xaml is so i can set width to star size and have the columns equal width.
I see most examples use an ObservableCollection but if I can bind to list why do I have to use this?开发者_如何学编程
Please let me knwo if my example requires further clarification
Edit: what I have now:
XAML:
<toolkit:DataGrid Name="dgFruit"
ItemsSource="{Binding}"
AutoGenerateColumns="False">
<toolkit:DataGrid.Columns>
<toolkit:DataGridTextColumn
Header="Name"
Width="5*"/>
<toolkit:DataGridComboBoxColumn
Header="Color"
Width="5*"/>
</toolkit:DataGrid.Columns>
</toolkit:DataGrid>
C#:
DataContext = fruitList;
Actually when I use DataContext I get no items. When I use ItemSource I get blank lines, but the correct number of rows so this seems more along the right lines.
I can get the data to show if I let it Auto generate columns. If I set autogeneratecolumns to false and then specify my columns in xaml like i want to to use star sizing, I get the right number of columns but no text!
First, this:
dgFruit.ItemsSource = "{Binding}"
should set the items source to a string containing the word Binding in braces. This is almost certainly not what you want (in fact, if you do this you should end up with a grid with nine rows, one for each character in the string!). You can set the ItemsSource in the XAML, or the code behind, but you shouldn't do both. Try the following:
<toolkit:DataGrid Name="dgFruit"
ItemsSource="{Binding}">
...
</toolkit:DataGrid>
And then in your visual's constructor:
...
InitializeComponents();
this.DataContext = fruitList;
...
Now the data context for your whole visual is the List<Fruit>, and the ItemsSource of your grid is set to be the same object. I'm assuming here that fruitList is a field of the visual itself.
The bindings for your columns should look something like:
<toolkit:DataGridTextColumn Header="Name"
Binding="{Binding Name}"
Width="5*" />
<toolkit:DataGridComboBoxColumn Header="Color"
ItemsSource="{Binding Source={StaticResource AllColors}}"
SelectedValueBinding="{Binding Path=Color}"
TextBinding="{Binding Path=Color}"
Width="5*" />
Where AllColors is defined as a resource (in this case):
<x:Array x:Key="AllColors"
Type="sys:String">
<sys:String>Orange</sys:String>
<sys:String>Yellow</sys:String>
</x:Array>
This should get you started.
WPF doesn't support binding to fields. Create a property that accesses fruitList
and bind to that.
// this is the field. you can't bind to this
private readonly List<Fruit> fruitList = new List<Fruit>();
// this is the property. you can bind to this
public List<Fruit> FruitList
{
get { return fruitList; }
}
Use dgFruit.DataContext = this;
instead of dgFruit.ItemsSource = "{Binding}";
And if you want to show these in a ComboBox, you need to bind those DataGridComboBoxColumn to a list of colors, not just a string. For example, your class might look like
public class Fruit
{
public string Name { get; set; }
public string Color { get; set; } // bind the combobox selectedvalue to this
public List<string> AvailableColors { get; set; } // bind the combobox ItemsSource to this
}
And you can use a List
if you like. The advantage of ObservableCollection
is it already implements INotifyCollectionChanged
and INotifyPropertyChanged
for you
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