c# - MVVM 中的双向数据绑定(bind)问题

Question

我正在尝试构建一个简单的 C#/WinFoms 项目，该项目根据结构使用 Model-View-ViewModel 设计模式:

两个 UserControl 和关联的 ViewModel 之间的数据绑定(bind)工作不正常。

MainForm 包含两个用户控件 (UC):Uc_Create、Uc_Iteration。每个 UC 都包含一个组合框，该组合框连接到 ViewModel_xxx 中的关联属性，即

Uc_Create 具有:

this.comboBox1ComplexCreate.DataSource = oVM_Create.VM_Create_ListOfStringsInModel; 

Uc_Iteration 有:

this.comboBox1ComplexIteration.DataSource = oVM_Iteration.VM_Iteration_ListOfStringsInModel;

问题:

当我向 VM_Iteration_ListOfStringsInModel 添加元素时，相应 UC (comboBox1ComplexCreate) 中的组合框和模型中的列表被正确更改但是Uc_Iteration 中的另一个组合框(comboBox1ComplexIteration)不是!

为什么？？？？

如果我将模型中的 List 更改为 BindingList，一切正常。我做错了什么？

提前致谢!

---

型号:

namespace Small_MVVM
{

    public class Model 
    {
        private static readonly object m_oLock = new object();

        private static Model instance;


        public List<string> simplelistOfStrings; 

        private Model()
        {
            simplelistOfStrings = new List<string>();
        }

        public static Model GetInstance()
        {
            if (instance == null)
            {
                lock (m_oLock)
                {
                    if (instance == null)
                    {
                        instance = new Model();
                    }
                }
            }
            return instance;
        }
    }
}

ModelView_Create:

namespace Small_MVVM
{
    class ViewModel_Create : NotifyPropertyChangedBase
    {
        private static Model oModel = Model.GetInstance();

        private BindingList<string> _VM_Create_ListOfStringsInModel = new BindingList<string>(oModel.simplelistOfStrings);
        public BindingList<string> VM_Create_ListOfStringsInModel
        {
            get
            {

                return _VM_Create_ListOfStringsInModel;
            }
            set
            {
                _VM_Create_ListOfStringsInModel = value;
                this.FirePropertyChanged(nameof(VM_Create_ListOfStringsInModel));
            }
        }
    }
}

ModelView_Iteration:

namespace Small_MVVM
{

    class ViewModel_Iteration : NotifyPropertyChangedBase
    {
        private static Model oModel = Model.GetInstance();

        public ViewModel_Iteration()
        {

        }

        BindingList<string> _VM_Iteration_ListOfStringsInModel = new BindingList<string>(oModel.simplelistOfStrings);
        public BindingList<string> VM_Iteration_ListOfStringsInModel
        {
            get
            {
                return _VM_Iteration_ListOfStringsInModel;
            }
            set
            {
                _VM_Iteration_ListOfStringsInModel = value;
                this.FirePropertyChanged(nameof(VM_Iteration_ListOfStringsInModel));
            }
        }
    }
}

这是实现 INotifyPropertyChange 接口(interface)的抽象类 NotifyPropertyChangedBase:

public abstract class NotifyPropertyChangedBase : INotifyPropertyChanged
{

    public event PropertyChangedEventHandler PropertyChanged;

    protected bool CheckPropertyChanged<T>(string propertyName, ref T oldValue, ref T newValue)
    {
            if (oldValue == null && newValue == null)
        {
                return false;
        }

        if ((oldValue == null && newValue != null) || !oldValue.Equals((T)newValue))
        {
            oldValue = newValue;
            return true;
        }

        return false;
    }

    private delegate void PropertyChangedCallback(string propertyName);

    protected void FirePropertyChanged(string propertyName)
    {
         if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

Answer 1

如果您遵循 MVVM 模式，那么您应该使用 ObservableCollection 进行如下所示的集合

   private ObservableCollection<int> _intList;
   public ObservableCollection<int> IntList
     {
        get
        {
          return _intList;
        }
        set
        {
           _intList= value;
           _intList.CollectionChanged += 
                        new System.Collections.Specialized.NotifyCollectionChangedEventHandler
                                            (MyProperty_CollectionChanged);
            }
        } 

void MyProperty_CollectionChanged(object sender,                        
         System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
  {
     NotifyPropertyChanged("IntList");
 }

ObservableCollection - 表示动态数据集合，在添加、删除项目或刷新整个列表时提供通知。

你也可以检查这个:MVVM (Model-View-ViewModel) Pattern For Windows Form Applications, using C#