从绑定传递的值作为字典中的键

Question

I tried to make a ListView of ListViews using dictionary in xaml, but i cant figure out how to.

I have a dictionary:

   public Dictionary<string, float> dictionary {get;set;}

And

    ObservableCollection<string> Parameters{get; set;}

containing names of key values in said dictionary.

I have a ListView with

    itemsSource = "{Binding Parameters}"

And an ListViews as DataTemplate with itemsSource that would be like:

    itemsSource= "{Binding dictionary[Passed_Value]}"

I cant manualy create ListViews with only selected values of Dictionary as user may choose which to display, and there are 10s of them.

Answer 1

Or maybe you just wonder how to access a dictionary using Binding.

Using this code:

public Dictionary<string, double> Items
{
    get
    {
        var d = new Dictionary<string, double>();
        foreach (var item in Enumerable.Range(1, 10))
        {
            d.Add($"Key{item}", item);
        }
        return d;
    }
}

And this XAML:

<ListView ItemsSource="{x:Bind Items}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <TextBlock>
                <Run Text="{Binding Key}" />
                <Run Text="=" />
                <Run Text="{Binding Value}" />
            </TextBlock>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

You will notice that I am not really accessing the dictionary using the key. There is no way to access a dictionary by key when the key is only known through binding. That is to say, you cannot pass a binding to a binding.

Here's what you can do:

<StackPanel DataContext="{Binding ElementName=ThisPage}">
    <TextBlock Text="{Binding Items[Key1]}" />
</StackPanel>

But, of course, this requires you know the key in advance and not bind to it. There is no multi-binding in WinRT-XAML.

I hope this clears up the confusion.

Answer 2

Your question is quite a challenge to understand. So, I thought I would just demonstrate creating a list of lists. Starting with this code-behind.

public class Level1
{
    public int Key { get; set; }
    public string Name { get; set; }
    public IEnumerable<Level2> Items { get; set; }
}

public class Level2
{
    public int Key { get; set; }
    public string Name { get; set; }
}

public IEnumerable<Level1> Items
{
    get
    {
        return Enumerable.Range(1, 10)
            .Select(x => new Level1
            {
                Key = x,
                Name = $"Level 1 Item {x}",
                Items = Enumerable.Range(1, 10)
                    .Select(y => new Level2
                    {
                        Key = y,
                        Name = $"Level 2 Item {y}",
                    })

            });
    }
}

And this XAML:

<ListView ItemsSource="{x:Bind Items}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel>
                <TextBlock Text="{Binding Name}" />
                <ItemsControl ItemsSource="{Binding Items}" Margin="12,0,0,0">
                    <ItemsControl.ItemTemplate>
                        <DataTemplate>
                            <StackPanel>
                                <TextBlock Text="{Binding Name}" />
                            </StackPanel>
                        </DataTemplate>
                    </ItemsControl.ItemTemplate>
                </ItemsControl>
            </StackPanel>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Looks like this:

Please note that I changed the nested ListView and made it an ItemsCOntrol because the nesting controls that each have a SELECTED behavior can cause you a real nightmare. Other than that, this does it. Not sure you need a Dictionary at all, but binding to a dictionary is certainly possible - just a little clunky.

Best of luck.