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Wpf datagrid row not updating when binded collection updated?

Answer 1

+1 A:

Your Product class has to implement INotifyPropertyChanged interface and you should update your bind-able properties to raise this event every time have changed. This is the way binding works in WPF. Something like this snippet

public class Produts : INotifyPropertyChanged
    {
public Produts()
        {

        }
    int productID;
    public int ProductID
    {
        get { return productID; }
        set
        {
            if (productID != value)
            {
                productID = value;
                OnPropertyChange("ProductID");
            }
        }
    }
    int quantity;
    public int Quantity
    {
        get { return quantity; }
        set
        {
            quantity = value;
            OnPropertyChange("Quantity");
            //Force Subtotal to be updated
            OnPropertyChange("SubTotal");
        }
    }
    string description;
    public string Description
    {
        get { return description; }

        set
        {
            description = value;
            OnPropertyChange("Description");
        }
    }
    decimal price;
    public decimal Price
    {
        get { return price; }
        set
        {
            price = value;
            OnPropertyChange("Price");
            //Force Subtotal to be updated
            OnPropertyChange("SubTotal");
        }
    }
    public decimal SubTotal
    {
        get { return Quantity * Price; }
    }

    public static List<Produts> ProductList
    {
        get
        {
            return new List<Produts>();
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChange(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Here's XAML:

<DataGrid ItemsSource="{Binding Path=ProductList}" AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTextColumn Header="ID" Binding="{Binding Path= ProductID}"/>
                <DataGridTextColumn Header="Quantity" Binding="{Binding Path=Quantity}"/>
                <DataGridTextColumn Header="Description" Binding="{Binding Path=Description}"/>
                <DataGridTextColumn Header="Price" Binding="{Binding Path=Price}"/>
                <DataGridTextColumn Header="Subtotal" Binding="{Binding Path=SubTotal, Mode=OneWay}"/>
            </DataGrid.Columns>
        </DataGrid>

And this line in Window's constructor

base.DataContext = new Produts();

Abdullah BaMusa 2010-05-31 12:44:03

I am facing same problem. I have implemented code as you said. Please help...public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } }public int ProductID{get { return productId; }set { if (productId != value) {productId = value;OnPropertyChanged("ProductID"); }}}

RAJ K 2010-05-31 14:50:38

While your code was true not supported by WPF Binding system also you have an issue that your implementation doesn't reflect your idea which you state it as when update Quantity the item must be updated. I Updated the code and included XAML and code behind to reflect this, try it now...

Abdullah BaMusa 2010-05-31 17:08:46

Mr. Abdullah it didn't work for me so i have edited my post and provide all code working on this binding. hope to get some positive answer. I tried your code you mentioned in your code but no sucess, after that i tried to manipulate things. so don't get angry. What i came to know that I am able to add items to List<> but not able to trigger the event to update DataGrid.thank you for help

RAJ K 2010-06-01 07:00:44

"What i came to know that I am able to add items to List<> but not able to trigger the event to update DataGrid". If so, then just inform UI to reflect this by firing PropertyChanged event every time you add an item which will require you to implement INotifyPropertyChanged interface where you define ProdcutList property

Abdullah BaMusa 2010-06-01 08:23:47

public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChange(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); Console.WriteLine("Not NULL"); } Console.WriteLine("Is NULL"); }this is returning null whenever i press SAVE button

RAJ K 2010-06-04 07:55:27

System.Windows.Data Error: 39 : BindingExpression path error: 'SubTotal' property not found on 'object' ''Object' (HashCode=5545401)'. BindingExpression:Path=SubTotal; DataItem='Object' (HashCode=5545401); target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String')

RAJ K 2010-06-04 08:03:13

Answer 2

A:

It has nothing to do with List or ObservableCollection. All the collection does is to notify the collection has been changed (eg. add a new item, remove a item, etc). It's the individual item itself that should notify UI that some of the fields have been changed. You can either use dependency property or implement INotifyPropertyChanged to utilize WPF property system.

Kai Wang 2010-05-31 12:48:15

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Wpf datagrid row not updating when binded collection updated?

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