在WPF C＃中填充ComboBox项

Question

I Have two classes like these:

public class Instance
{
    /// <summary>
    /// Identity of index
    /// </summary>
    public int Id { get; set; }

    /// <summary>
    /// Items within this group.
    /// </summary>
    public Dictionary<string, ItemRow> Items;

    public Instance()
    {
        //Items = new Dictionary<string, ItemRow>();
        Items = new Dictionary<string, ItemRow>();
    }
}

public class GroupMemory
{
    /// <summary>
    /// Name of the OPC group
    /// </summary>
    public string Name { get; set; }
    /// <summary>
    /// Scan rate for this group.
    /// </summary>
    public string ScanRate { get; set; }
    /// <summary> 
    /// Number of instances for this group.
    /// </summary>
    public int CountOfInstances { get; set; }

    /// <summary>
    /// Instances within this group.
    /// </summary>
    public Dictionary<int, Instance> Instances;
    /// <summary>
    /// Items within this group.
    /// </summary>
    public Dictionary<string, ItemRow> Items;

    /// <summary>
    /// Constructor of GroupMemory class.
    /// </summary>
    public GroupMemory()
    {
        Items = new Dictionary<string, ItemRow>();
        Instances = new Dictionary<int, Instance>();
    }
}

I have a listview that i bind GroupMemory object in each item of listview. Last column of listview is a ComboBox that i need to bind Id of each instances of a groupmemory in it. for example if each group memory contains two instances and instances have Id=1 and Id=2, i want to show 1 and 2 in combobox as its items. how can i write xaml code for combobox or its code behinde?

here is my xaml code for listview

<ListView.View>
            <GridView>
                <GridViewColumn Header="Name" Width="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ListView}, Converter={StaticResource starWidthConverter}}"  DisplayMemberBinding="{Binding Path=Name}" />
                <GridViewColumn Header="Scan Rate" Width="60" DisplayMemberBinding="{Binding Path=ScanRate}" />
                <GridViewColumn Header="Instances" Width="60" DisplayMemberBinding="{Binding Path=CountOfInstances}" />
                <GridViewColumn Header="Index" Width="100">
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <ComboBox Width="50" ItemsSource="{Binding Instances}" SelectedValue="{Binding Id}" DisplayMemberPath="Id"/>
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>
            </GridView>
        </ListView.View>

Answer 1

Assuming that DataContext of the ComboBox is an instance of GroupMemory class, you can try to bind ComboBox's ItemsSource to Instances.Values property and set DisplayMemberPath to display Id of each Instance :

<ComboBox ItemsSource="{Binding Instances.Values}"
          DisplayMemberPath="Id"
          SelectedValuePath="Id"/>

Answer 2

Your Instances is declared as a field and it's not a valid binding source . You should convert it to a property if you want to bind to it. Change declaration to:

public Dictionary<int, Instance> Instances { get; set; }

and then, because it's a Dictionaty<K, V> , and each item is of a KeyValuePair<K, V> type where Key is your int and Value is your Instance try changing DisplayMemberPath to Value.Id

<ComboBox ItemsSource="{Binding Instances}" DisplayMemberPath="Value.Id"/>

Answer 3

If you bind the itemsource to the Instances property, you could then bind the DisplayMember and/or valuemember to Key or Value.

Its relatively simple

Instances is a KeyValuePair, you will need to bind to Value.Id

However i also noticed that neither of your classes implement INotifyPropertyChanged. You will need to implement this as this is how the Binding knows your values have been updated.

You may also need to check out the ObservableDictionary if you're stuck on using a dictionary. http://blogs.microsoft.co.il/shimmy/2010/12/26/observabledictionarylttkey-tvaluegt-c/