DICTIONARY FAILURE BINDING IN WPF

Ankita Pandey

Total Post:183

Points:1285
Posted by  Ankita Pandey
WPF 
WPF
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I have most of the textblock and radio button objects in my app bound to my dictionnary

I store the new value in a Dictionary.

The problem is that the binding failure is throwing an exception that is very slow.

Here is an example: (this code runs correctly, it is just slow if it can't find a match in the start app.)

<StackPanel>
    <TextBox Text="{Binding Dictio[0], Mode=TwoWay}"/>
    <TextBox Text="{Binding Dictio[1], Mode=TwoWay}"/>
    <RadioButton GroupName="select" IsChecked="{Binding Dictio[2], Mode=TwoWay}" Content="true"/>
</stackPanel>

And in my class

    private Dictionary<int, object> _Dictio;
 public MainWindow()
        {
            Dictio = new Dictionary<int, object>();
            this.DataContext = this;
            InitializeComponent();
        }
public Dictionary<int, object> Dictio
        {
            get { return _Dictio; }
            set { _Dictio = value; }
        }
private void test(object sender, RoutedEventArgs e)
{
    foreach (KeyValuePair<int, object> kvp in Dictio)
            {
                Console.Out.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
        }
}

When I try to start app and the binding tries to lookup Dictio[key], I get this in my output window for all the key of my dictionnary Dictio:

 System.Windows.Data Error: 17 : Cannot get 'Item[]' value (type 'Object') from 'Dictio' (type 'Dictionary`2'). BindingExpression:Path=Dictio[4]; DataItem='MainWindow' (Name=''); target element is 'RadioButton' (Name='mm'); target property is 'IsChecked' (type 'Nullable`1') TargetInvocationException:'System.Reflection.TargetInvocationException: Une exception a été levée par la cible d'un appel. ---> System.Collections.Generic.KeyNotFoundException: La clé donnée était absente du dictionnaire.

System.Collections.Generic.Dictionary`2.get_Item(TKey key)

  --- Fin de la trace de la pile d'exception interne ---

 System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)

System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)

 System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)

 System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)

 MS.Internal.Data.PropertyPathWorker.GetValue(Object item, Int32 level)

 MS.Internal.Data.PropertyPathWorker.RawValue(Int32 k)'

Is there a way to make the connection not throw an exception if the dictionary is empty?

  1. Pravesh Singh

    Post:412

    Points:2888
    Re: Dictionary Failure binding in WPF

    Hi Ankita,


    I use your class CustomDictionary

    This is my xaml file

    <StackPanel>
        <TextBox Name="textBox1" Text="{Binding Dictio[0], Mode=TwoWay}"/>
        <TextBox Name="textBox2" Text="{Binding Dictio[1], Mode=TwoWay}"/>
        <RadioButton Name="radioButton" GroupName="select" IsChecked="{Binding Dictio[2], Mode=TwoWay}" Content="true"/>
    <Button Content="test" Click="test"/>
    </StackPanel>
    In my class
        private CustomDictionary _Dictio;
     public MainWindow()
            {
                Dictio = new CustomDictionary();
                this.DataContext = this;
                InitializeComponent();
            }
        public CustomDictionary Dictio
                {
                    get { return _Dictio; }
                    set { _Dictio = value; }
                }
        private void test(object sender, RoutedEventArgs e)
        {
            foreach (KeyValuePair<int, object> kvp in Dictio)
                    {
                        Console.Out.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
                }
        }

    when i execute i have this error

    Une exception de première chance de type 'System.Collections.Generic.KeyNotFoundException' s'est produite dans mscorlib.dll

    in your class CustomDictionnary in

     return properties[index].Item1.GetValue(properties[index].Item2);

      Modified On Apr-04-2018 05:14:50 AM

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