Binding a property of an object of a class inside another doesn't work

Question

I have an strange problem with binding in WPF . There is a simple sample of what i'm doing:

 public class Project
 {
    private string _title;
    public string Title
    {
        get { return _title; }
        set
        {
            _title= value;
            RaisePropertyChanged("Title");
        }
    }
 }

 public class People
 {
   private string _name;
   public string Name
   {
      get { return _name; }
      set
      {
        _name= value
        RaisePropertyChanged("Name");
      }
   }

   private Project _project;
   public Project Project 
   {
      get { return _project; }
      set
      {
        _project= value;
        RaisePropertyChanged("Project");
      }
   }
}

Now I bound a grid to an instance of People in the view and it can bind controls to Project and Name of People class, but I really can't understand why I can not bind to Project.Title .

I write my XAML code like this:

<TextBox Text="{Binding Name}"/>
<Combobox .... SelectedItem="{Binding Project}"/>
<TextBox Text="{Binding Project.Title}"/>

The first two controls above get bounded correctly but the last TextBox doesn't. I have no idea why it can access to Project but not Project.Title ? It's an another weird thing I've already seen in WPF!

Answer 1

Perhaps your combo box selection is not setting the selected value without using Mode=TwoWay :

<Combobox .... SelectedItem="{Binding Project, Mode=TwoWay}"/>

Once the Project is set, the property is set, the Title will show.

Answer 2

Try "Path=Project.Title". Worked for me in a same case.

Answer 3

if your DataContext is an instance of your Person object it should work. you can check your bindings at runtime with Snoop ( http://snoopwpf.codeplex.com/ ) btw. give it a try :)

you can also do

<TextBox DataContext="{Binding Project, Mode=OneWay}" Text="{Binding Title}"/>

Answer 4

谢谢大家，但问题不是我的想法。实际上我使用PropertyChanged.Fody将INotifyPropertyChanged注入属性，但似乎未达到我的预期。我自己实现了INotifyPropertyChanged ，现在可以正常工作。