如何直接绑定XAML UWP中的属性

Question

 public sealed partial class MainPage : Page
    {
        //public static dynamic resource;

        public  ResourceModel vm = new ResourceModel();        

        public MainPage()
        {
            this.InitializeComponent();              
        }
     }


public class ResourceModel 
    {
        private Dictionary<string, string> _resource;
        public Dictionary<string, string> Resource
        {
            get { return _resource; }
            set
            {
               _resource=Value;
            }
        }
    }

Xaml Code

<TextBlock Text="{Binding vm.Resource[Account] ,Mode=TwoWay}" FontSize="15" Margin="10 0 30 0" Foreground="White" VerticalAlignment="Top" HorizontalAlignment="Center" Grid.Row="1" Grid.Column="0"></TextBlock>

Description I want to bind my textblock from the ResourceModel without DataContext and Name of textblock. Only i need binding using property Name.

Answer 1

There are a few places which you're missing out. Below is some information on em:

1. The Binding is searching for a data context which is not available. In case you don't have a viewmodel and you want to use the legacy binding to bind UI elements to the code behind you need to add DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}" in your <Page> tag of xaml . This will tell the Binding Engine that you're binding to the code behind.
2. Also, you can't bind to fields, you can only bind to properties as fields don't have a get and set . So in your code behind your vm is a field and not a property. Change it to public ResourceModel vm { get; set; } = new ResourceModel(); public ResourceModel vm { get; set; } = new ResourceModel(); and it'll start working.

---

That being said, there are 3 ways you can go about it:

1. using binding to codebehind:

In the <page> tag add the DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}" for telling the binding engine that you'll be binding to code behind.

Your textblock code looks like below:

<TextBlock Text="{Binding vm.Resource[Account]}"/>

I don't understand why is the Mode set to two way as it's a Textblock and is un-editable and legacy binding is by default oneWay .

2. using binding with ResourceModel

Another way would be to set the data context of the textblock to directly bind to the Model. below is the code:

 <TextBlock Text="{Binding Resource[Account]}">
       <TextBlock.DataContext>
            <local:ResourceModel/>
       </TextBlock.DataContext>
  </TextBlock>

3. use x:bind for code behind binding

The x:bind by default binds to the code behind so you can use x:bind instead of binding. The issue you face with x:bind is because you can't set in the key in xaml when using x:bind. Use converters and then pass in your key as a converter parameter and it'll all start to work just fine. if you do plan on using it below is the xaml code:

<TextBlock Text="{x:Bind vm.Resource,Converter={StaticResource DictionaryValueFetcher},ConverterParameter='account'}"/>