可观察集合在运行时不从SQL Server数据库更新

Question

我已经实现了INotifyPropertyChanged和Observable集合，但我在数据库中所做的更改未在运行时的DataGrid（UI未更新）中反映出来。林新的C＃和WPF。这是我的代码。

模型和视图模型：

namespace WpfApplication4.ViewModels 
{ 
    public class MainViewModel : INotifyPropertyChanged 
    { 
     Model _myModel = new Model(); 
     private ObservableCollection<VItalView> _vitalview = new ObservableCollection<VItalView>(); 
     public ObservableCollection<VItalView> Vitalview 
     { 
      get { return _vitalview; } 
      set 
      { 
       _vitalview = value; 
       OnPropertyChanged("Vitalview"); 
      } 
     } 
     public MainViewModel() 
     { 
      initializeload(); 
     } 
     private void initializeload() 
     { 
      DataTable table = _myModel.getData(); 

      for (int i = 0; i < table.Rows.Count; ++i) 
       Vitalview.Add(new VItalView 
       { 
        Weight = Convert.ToInt32(table.Rows[i][0]), 
        Height = Convert.ToInt32(table.Rows[i][1]), 
        BMI = Convert.ToInt32(table.Rows[i][2]), 
       }); 
     } 

     public event PropertyChangedEventHandler PropertyChanged; 
     public void OnPropertyChanged(string propertyname) 
     { 
      var handler = PropertyChanged; 
      if (handler != null) 
       handler(this, new PropertyChangedEventArgs(propertyname)); 
     } 
    } 

    public class Model 
    { 
     public DataTable getData() 
     { 
      DataTable ndt = new DataTable(); 
      SqlConnection con = new SqlConnection("Data Source=DESKTOP-QTFGN00; Initial Catalog=VITALS;Integrated Security=true"); 

      con.Open(); 
      SqlCommand cmd = new SqlCommand("SELECT * FROM Vitals", con); 


      SqlDataAdapter da = new SqlDataAdapter(cmd); 
      da.SelectCommand = cmd; 

      da.Fill(ndt); 
      return ndt; 
     } 
    } 
} 

和视图：

namespace WpfApplication4.Models 
{ 
    public class VItalView : INotifyPropertyChanged, IDataErrorInfo 
    { 
     public VItalView() 
     { 
     } 

     private float weight; 

     public float Weight 
     { 
      get { return weight; } 
      set 
      { 
       weight = value; 
       OnPropertyChanged("Weight"); 
      } 
     } 

     private float height ; 

     public float Height 
     { 
      get { return height; } 
      set 
      { 
       height = value; 
       OnPropertyChanged("Height"); 
      } 
     } 

     private float bmi; 

     public float BMI 
     { 
      get { return bmi; } 
      set 
      { 
       bmi = value; 
       OnPropertyChanged("Bmi"); 
      } 
     } 

     public event PropertyChangedEventHandler PropertyChanged; 
     private VItalView vv; 

     protected void OnPropertyChanged(string propertyname) 
     { 
      var handler = PropertyChanged; 
      if (handler != null) 
       handler(this, new PropertyChangedEventArgs(propertyname)); 
     } 

     public string Error 
     { 
      get { return null; } 
     } 

     public string this[string columnName] 
     { 
      get 
      { 
       string error = null; 
       switch (columnName) 
       { 
        case "Weight": 
         if (weight<10) 
         { 
          error = "Fdddd"; 
         } 
         break; 

        case "Height": 
         if ((height < 18) || (height > 85)) 
         { 
          error = "bhhj."; 
         } 
         break; 
        case "BMI": 
         if (bmi>70) 
         { 
          error = "xxx"; 
         } 
         break; 
       } 
       return (error); 
      } 
     } 
    } 
} 

Answer 1

嗯，这不会喜欢这个工作。其实ObservableCollection<T>将在该属性将被修改的情况下工作。

SQL Server不通知应用程序在那里添加了任何东西。