我的组合框“选择值”绑定不会在双向数据绑定中返回

Question

我正在使用简单的MVVM框架创建一个简单的Silverlight 4.0 LOB应用程序。

我有一个雇员列表视图，其中显示了所有雇员的列表，并且在EmployeeListViewModel中有一些属性，如下所示：

    private Grade selectedGrade;
    public Grade SelectedGrade
    {
        get { return selectedGrade; }
        set
        {
            selectedGrade = value;
            NotifyPropertyChanged(m => m.SelectedGrade);
        }
    }

    private Religion selectedReligion;
    public Religion SelectedReligion
    {
        get { return selectedReligion; }
        set
        {
            selectedReligion = value;
            NotifyPropertyChanged(m => m.SelectedReligion);
        }
    }
    private ObservableCollection<Grade> grades;
    public ObservableCollection<Grade> Grades
    {
        get { return grades; }
        set
        {
            grades = value;
            NotifyPropertyChanged(m => m.Grades);
        }
    }

    private ObservableCollection<Religion> religions;
    public ObservableCollection<Religion> Religions
    {
        get { return religions; }
        set
        {
            religions = value;
            NotifyPropertyChanged(m => m.Religions);
        }
    }
    private ObservableCollection<Department> departments;
    public ObservableCollection<Department> Departments
    {
        get { return departments; }
        set
        {
            departments = value;
            NotifyPropertyChanged(m => m.Departments);
        }
    }
    private Employee selectedEmployee;
    public Employee SelectedEmployee
    {
        get { return selectedEmployee; }
        set
        {
            selectedEmployee = value;
            SetCanProperties();
            NotifyPropertyChanged(m => m.SelectedEmployee);
        }
    }
    private ObservableCollection<Employee> employees;   
    public ObservableCollection<Employee> Employees
    {
        get { return employees; }
        set
        {
            employees = value;
            NotifyPropertyChanged(m => m.Employees);
        }
    }
    private Department selectedDepartment;
    public Department SelectedDepartment
    {
        get { return selectedDepartment; }
        set
        {
            selectedDepartment = value;
            NotifyPropertyChanged(m => m.SelectedDepartment);
        }
    }

现在在我看来，我有一个按钮可以编辑“员工列表”中的选定员工，这将打开一个新的子窗口，其中包含要编辑的EmployeeDetails

  EmployeeListViewModel viewModel;
    public EmployeeListView()
    {
        InitializeComponent();
        viewModel = (EmployeeListViewModel)DataContext;
    }

这是编辑员工方法

 private void editItemButton_Click(object sender, RoutedEventArgs e)
    {
        // Exit if no product selected
        if (viewModel.SelectedEmployee == null) return;

        // Create a product detail model
       EmployeeDetailViewModel detailModel =
            new  EmployeeDetailViewModel(viewModel.SelectedEmployee);
        // set comboboxes !! 

       detailModel.Departments = viewModel.Departments;
       detailModel.Religions = viewModel.Religions;

       detailModel.Grades = viewModel.Grades;

        // Start editing
        detailModel.BeginEdit();

        // Show EmployeeDetail view
       EmployeeDetailView itemDetail = new  EmployeeDetailView(detailModel);
        itemDetail.Closed += (s, ea) =>
        {
            if (itemDetail.DialogResult == true)
            {
                // Confirm changes

                detailModel.EndEdit();
            }
            else
            {
                // Reject changes
                detailModel.CancelEdit();
            }
        };
        itemDetail.Show();
    }

现在就我的详细信息子视图我有这个承包商

   public EmployeeDetailView(EmployeeDetailViewModel viewModel)
    {
        InitializeComponent();
        DataContext = viewModel;
    }

这是我的DetailsViewModel承包商

   public EmployeeDetailViewModel(Employee model)
    {
        base.Model = model;
    }
         private ObservableCollection<Religion> religions;
    public ObservableCollection<Religion> Religions
    {
        get { return religions; }
        set
        {
            religions = value;
            NotifyPropertyChanged(m => m.Religions);
        }
    }

    private ObservableCollection<Grade> grades;
    public ObservableCollection<Grade> Grades
    {
        get { return grades; }
        set
        {
            grades = value;
            NotifyPropertyChanged(m => m.Grades);
        }
    }
    private ObservableCollection<Department> departments;
    public ObservableCollection<Department> Departments
    {
        get { return departments; }
        set
        {
            departments = value;
            NotifyPropertyChanged(m => m.Departments);
        }
    }

绑定完成之后，我有了三个部门，宗教和职系的组合框（这是我的员工表中的外键）

 <ComboBox  ItemsSource="{Binding Departments}" DisplayMemberPath="DepartmentName" SelectedValue="{Binding Model.Emp_Department, Mode=TwoWay}" SelectedValuePath="DepartmentId"/>
   <ComboBox  ItemsSource="{Binding Grades}" DisplayMemberPath="GradeName" SelectedValue="{Binding Model.Emp_Grade, Mode=TwoWay}" SelectedValuePath="GradeId"/>

等等。问题是当我更改其值时，只有“部门”组合框正在更新源值

和其他组合框也不..即使绑定语句完全相同！

很抱歉写了这么多..但是有人可以帮我吗？

非常感谢

Answer 1

不幸的是，您将MVVM分离弄得有些混乱，因为您直接从View绑定到了基础模型（意味着ViewModel中的任何业务逻辑/验证）都被绕过了。

但是，您似乎已经准备就绪，因此我建议以下几点：

将您的Xaml更改为此（注意，从SelectedValue更改为SelectedItem）：

<ComboBox  ItemsSource="{Binding Departments}" DisplayMemberPath="DepartmentName" SelectedItem="{Binding SelectedDepartment, Mode=TwoWay}"/>
<ComboBox  ItemsSource="{Binding Grades}" DisplayMemberPath="GradeName" SelectedItem="{Binding SelectedGrade, Mode=TwoWay}"/>

然后，在SelectedDepartment / SelectedGrade属性的设置器中，执行所有必需的验证，然后将所选项目的ID写入（详细）模型中的属性。

希望能帮助到你。

Answer 2

好吧，这就是我如何做我的连击：

 <ComboBox ItemsSource="{Binding Path=ListPeople, UpdateSourceTrigger= PropertyChanged}" SelectedItem="{Binding Path=SelectedPerson, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" DisplayMemberPath="FirstName"/>

在我的视图模型中：

 private ObservableCollection<Person> listPeople = new ObservableCollection<Person>();

 public IEnumerable<Person> ListPeople
     {
         get { return this.listPeople; }
     }

 public Person SelectedPerson
     {
         get { return selectedPerson; }
         set
         {
             selectedPerson = value;
             if (selectedPerson != null)
             {
                 NextToPayID = selectedPerson.PersonID;
             }
             base.RaisePropertyChanged("SelectedPerson");
         }
     }

看看是否可以使用它来提供帮助！