为了能更好的得到帮助，我将问题代码都分离出以下的这种形式。别问我为啥这样做，业务需求啦。
页面A绑定的全部学生信息，以列表的形式展示，可以进行增删改查。
页面B绑定的是前N名次的学生信息，以自定义DataGrid展示。
页面A操作数据后，页面B会立刻通知更新。
问题
一，QueryAllBtn_Click方法中查询前50名学生信息的代码Cache.OcAList集合数据变更了，为什么页面没有变更的呢？
不是在初始化中this.AllUserGrid.ItemsSource = Cache.OcAList;这样进行绑定了吗？
每一次查询都需要绑定？可是DeleteUserBtn_Click删除数据页面又会更新。
二，CollectionChanged都重新赋值了，为什么不会进DisplayViewModel这个类的UpdateDisplayList这个方法呢？CollectionChanged重新赋值会触发什么事件呢？
全部代码如下
一：学生信息类
using System;
using System.Linq;
using SG.Views.Base.Model;
using System.Collections.Generic;
namespace SG.com.ll.Config
{
public class User : ViewModelBase
{
public string ID { get; set; }//ID不可修改
public string Name { get; set; }//姓名不可修改
private int score;//成绩可以修改
public int Score
{
get { return score; }
set
{
if (score == value) return;
score = value; this.OnPropertyChanged("Score");
}
}
}
}
二：数据缓存类
using System;
using System.Linq;
using System.ComponentModel;
using System.Collections.Generic;
using System.Collections.ObjectModel;
namespace SG.com.ll.Config
{
/// <summary>
/// 测试类
/// </summary>
public class Cache
{
//第一个集合，计划展示全部数据
private static ObservableCollection<User> ocAList = new ObservableCollection<User>();
//第二个集合，计划展示前3名的数据
private static ObservableCollection<User> ocBList = new ObservableCollection<User>();
public static ObservableCollection<User> OcAList
{
get { return Cache.ocAList; }
set { Cache.ocAList = value; }
}
public static ObservableCollection<User> OcBList
{
get { return Cache.ocBList; }
set
{
Cache.ocBList = value;
Console.WriteLine("集合2中的数据条数是:" + Cache.ocBList.Count);
for (int i = 0; i < Cache.ocBList.Count; i++)
{
string a = Cache.ocBList[i].Name;
Console.WriteLine(a);
}
OnStaticPropertyChanged("OcBList");
}
}
public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged;
private static void OnStaticPropertyChanged(string propertyName = null)
{
if (propertyName.StartsWith("get_") || propertyName.StartsWith("set_"))
{
propertyName = propertyName.Substring("get_".Length);
}
OnStaticPropertyChanged(new PropertyChangedEventArgs(propertyName));
}
private static void OnStaticPropertyChanged(PropertyChangedEventArgs e)
{
if (StaticPropertyChanged == null) return;
StaticPropertyChanged.Invoke(null, e);
}
}
}
三：数据模型类
using System;
using System.Linq;
using SG.com.ll.Config;
using SG.Views.Base.Model;
using SG.com.ll.Config.Notice;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
namespace SG.Views.Main
{
public class DisplayViewModel : ViewModelBase
{
/// <summary>
/// 首页数据模型
/// </summary>
/// <param name="n"></param>
public DisplayViewModel(int n)
{
UpdateDisplayList(null, n);
Cache.OcAList.CollectionChanged += (s, e) => UpdateDisplayList(e, n);
}
/// <summary>
/// 首页数据筛选方法
/// </summary>
/// <param name="n"></param>
private void UpdateDisplayList(NotifyCollectionChangedEventArgs e, int n)
{
Console.WriteLine("------------------------------------");
if (e != null)
{
if (e.Action == NotifyCollectionChangedAction.Add)
{
Console.WriteLine("添加被触发");
}
else if (e.Action == NotifyCollectionChangedAction.Remove)
{
Console.WriteLine("删除被触发");
}
else if (e.Action == NotifyCollectionChangedAction.Replace)
{
Console.WriteLine("替换被触发");
}
}
else
{
Console.WriteLine("初始化触发");
Cache.OcBList = new ObservableCollection<User>(Cache.OcAList.Take(n));
}
}
}
}
四：页面A代码
/// <summary>
/// 初始化
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Window_Loaded(object sender, RoutedEventArgs e)
{
//得到1000个学生信息
Cache.OcAList = myDB.GetUser(1000);
//进行绑定
this.AllUserGrid.ItemsSource = Cache.OcAList;
}
/// <summary>
/// 只查询50个学生信息
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void QueryAllBtn_Click(object sender, RoutedEventArgs e)
{
Cache.OcAList = myDB.GetUser(50);
}
/// <summary>
/// 修改选中学生的成绩
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void UpdateUserBtn_Click(object sender, RoutedEventArgs e)
{
User user = this.AllUserGrid.SelectedItem as User;
user.Score = 100;
}
/// <summary>
/// 删除学生
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void DeleteUserBtn_Click(object sender, RoutedEventArgs e)
{
int index = this.AllUserGrid.SelectedIndex;
Cache.OcAList.RemoveAt(index);
}
五：B页面代码
/// <summary>
/// 初始化
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Window_Loaded(object sender, RoutedEventArgs e)
{
//数据模型初始化
new DisplayViewModel(3);
//进行绑定
this.TOPUserScoreGrid.ItemsSource = Cache.OcBList;
}
