如何根据提供要绑定到的属性名称的字符串属性绑定TextBox.Text？

Question

Quite junior to WPF :)

Context

I have a Window with a DataContext containing a few ints. My window is basically just used to display "Key : Value" for each int, Value being an editable TextBox.

As I edited my window to provide ValueConverters and ValidationRules, it appeared to me that I could use some generic classes, as they all have the same rules / converters.

Problem

Let's say I have int property_a, int property_b, int property_c; in my DataContext. I have no idea on how to bind the content of the TextBox inside the generic class to those properties :/

I wanted to provide a string property like "property_a" to my generic class, but I then couldn't find how to make a dynamic binding using this property.

Code Samples

• My customized TextBox wrapper :

<Grid>
        <TextBox x:Name="IntBox" Grid.Row="1" Grid.Column="1" Margin="0, 5, 10, 5"
                 Style="{StaticResource TextBoxInError}">
            <TextBox.Text>
                <Binding Path="{no idea what to put here }">
                    <Binding.ValidationRules>
                        <validation:IntRule />
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
    </Grid>

public partial class IntTextBox : UserControl
    {
        public string PropertyToBind { get; set; }

        public IntTextBox()
        {
            InitializeComponent();
        }
    }

• The spot where I use my TextBox wrapper in my Window :

<input:IntTextBox x:Name="InitiativeBox" Grid.Row="1" Grid.Column="1" Margin="0, 5, 10, PropertyToBind="Initiative"/>

Thanks for your reading :)

Answer 1

The short answer to your question is: You put the name of the public property which is in your datacontext.

I'm not sure that's a totally helpful answer though.

You might find this sample thought provoking:

https://social.technet.microsoft.com/wiki/contents/articles/29777.wpf-property-list-editing.aspx

Maybe you should take a look at some super simple stuff first though:

https://social.technet.microsoft.com/wiki/contents/articles/31915.wpf-mvvm-step-by-step-1.aspx

https://social.technet.microsoft.com/wiki/contents/articles/32164.wpf-mvvm-step-by-step-2.aspx

Answer 2

You'll be creating the binding in code behind. PropertyToBind should be a dependency property, since it's a property of a UI element and you may want to bind it. We'll also rename it to PropertyPath , because that's consistent with how similar properties such as ListBox.SelectedValuePath are named in the WPF framework.

Here's the XAML. Grid.Row and Grid.Column index from 0, not 1. You don't need them anyway, because you didn't define any rows or columns in your Grid (if this is a partial example and you simply omitted the row/column definitions, disregard those remarks).

<Grid>
    <TextBox 
        x:Name="IntBox" 
        Margin="0, 5, 10, 5"
        Style="{StaticResource TextBoxInError}"
        />
</Grid>

Code behind:

public partial class IntTextBox : UserControl
{
    public IntTextBox()
    {
        InitializeComponent();
    }

    public String PropertyPath
    {
        get { return (String)GetValue(PropertyPathProperty); }
        set { SetValue(PropertyPathProperty, value); }
    }

    public static readonly DependencyProperty PropertyPathProperty =
        DependencyProperty.Register(nameof(PropertyPath), typeof(String), 
            typeof(IntTextBox),
            new FrameworkPropertyMetadata(PropertyPath_PropertyChanged));

    protected static void PropertyPath_PropertyChanged(DependencyObject d, 
        DependencyPropertyChangedEventArgs e)
    {
        var ctl = d as IntTextBox;

        var binding = new Binding(ctl.PropertyPath)
        {
            ValidationRules = { new IntRule() },

            //  Optional. With this, the bound property will be updated and validation 
            //  will be applied on every keystroke. Fine for integers. For doubles 
            //  or phone numbers, it'll drive your users up the wall. 
            UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged
        };

        ctl.IntBox.SetBinding(TextBox.TextProperty, binding);
    }
}

I'm not sure what you're doing here is necessarily a good idea in this particular case, but the technique is respectable and that's how you do it.