我的組合框“選擇值”綁定不會在雙向數據綁定中返回

Question

我正在使用簡單的MVVM框架創建一個簡單的Silverlight 4.0 LOB應用程序。

我有一個雇員列表視圖，其中顯示了所有雇員的列表，並且在EmployeeListViewModel中有一些屬性，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);
        }
    }

現在在我看來，我有一個按鈕可以編輯“員工列表”中的選定員工，這將打開一個新的子窗口，其中包含要編輯的EmployeeDetails

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

這是編輯員工方法

 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();
    }

現在就我的詳細信息子視圖我有這個承包商

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

這是我的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);
        }
    }

綁定完成之后，我有了三個部門，宗教和職系的組合框（這是我的員工表中的外鍵）

 <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。問題是當我更改其值時，只有“部門”組合框正在更新源值

和其他組合框也不..即使綁定語句完全相同！

很抱歉寫了這么多..但是有人可以幫我嗎？

非常感謝

Answer 1

不幸的是，您將MVVM分離弄得有些混亂，因為您直接從View綁定到了基礎模型（意味着ViewModel中的任何業務邏輯/驗證）都被繞過了。

但是，您似乎已經准備就緒，因此我建議以下幾點：

將您的Xaml更改為此（注意，從SelectedValue更改為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屬性的設置器中，執行所有必需的驗證，然后將所選項目的ID寫入（詳細）模型中的屬性。

希望能幫助到你。

Answer 2

好吧，這就是我如何做我的連擊：

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

在我的視圖模型中：

 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來提供幫助！