WPF数据绑定

数据绑定是一个很强大且优雅的技能，之前用过好多次，但有些地方总不是特别清晰，常常需要重新翻阅资料来回顾，于是这次用了几天时间好好梳理一下，记录一下。

首先数据绑定对数据对象的要求：需要是公有属性（不支持字段和私有属性）。

如果需要在数据内容发生变化时自动更新到控件，则需要实现INotifyPropertyChanged接口，其包含 PropertyChanged事件，在属性变化时引发PropertyChanged事件。

如果绑定对象为集合时，需要在集合内容发生变化时自动更新到控件，则需要INotifyCollectionChanged接口，其包含CollectionChanged事件，目前内置的泛型集合 ObservableCollection 实现了该接口。

通常在设置绑定时，我们需要指定数据上下文，DataContext，如果控件没有设置DataContext，则会去找父容器的DataContext，依层级依次查找。也有些控件直接在代码中指定ItemsSource的。如果要绑定的数据依赖于另外一个控件的值，可以在DataContext中，绑定到另外一个控件的选中项，然后设置该控件的数据源或者绑定值。

MainWindow.xaml

    
        
            BindData:
            
        
        
            BindDatas:
            
        
        
            
        
        
            ExchangeID:
            
        
        
            InstrumentID:
            
        
        
            InstrumentName:
            
        
    

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;

namespace TestBinding;

public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler? PropertyChanged;
    protected virtual void OnPropertyChanged([CallerMemberName] string? propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    protected virtual bool SetProperty(ref T member, T value, [CallerMemberName] string? propertyName = null)
    {
        if (EqualityComparer.Default.Equals(member, value))
        {
            return false;
        }
        member = value;
        OnPropertyChanged(propertyName);
        return true;
    }
}
public class ExchangeViewModel : ViewModelBase
{
    private string exchangeID = string.Empty;
    public string ExchangeID { get => exchangeID; set => SetProperty(ref exchangeID, value); }
    public ObservableCollection Instruments { get; set; } = new ObservableCollection();
}
public class InstrumentViewModel : ViewModelBase
{
    public InstrumentViewModel(string exchangeID, string instrumentID, string instrumentName)
    {
        ExchangeID = exchangeID;
        InstrumentID = instrumentID;
        InstrumentName = instrumentName;
    }

    private string _exchangeID = string.Empty;
    private string _instrumentID = string.Empty;
    private string _instrumentName = string.Empty;
    public string ExchangeID { get => _exchangeID; set => SetProperty(ref _exchangeID, value); }
    public string InstrumentID { get => _instrumentID; set => SetProperty(ref _instrumentID, value); }
    public string InstrumentName { get => _instrumentName; set => SetProperty(ref _instrumentName, value); }
}
/// 

/// Interaction logic for MainWindow.xaml
/// 
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        parentContainer.DataContext = this;

        Exchanges = new();
        ExchangeViewModel exchange1 = new ExchangeViewModel();
        exchange1.ExchangeID = "SHSE";
        exchange1.Instruments.Add(new InstrumentViewModel("SHSE", "601155", "新城控股"));
        exchange1.Instruments.Add(new InstrumentViewModel("SHSE", "600036", "招商银行"));
        exchange1.Instruments.Add(new InstrumentViewModel("SHSE", "600266", "城建发展"));
        exchange1.Instruments.Add(new InstrumentViewModel("SHSE", "600837", "海通证券"));
        exchange1.Instruments.Add(new InstrumentViewModel("SHSE", "601668", "中国建筑"));
        ExchangeViewModel exchange2 = new ExchangeViewModel();
        exchange2.ExchangeID = "SZSE";
        exchange2.Instruments.Add(new InstrumentViewModel("SZSE", "000002", "万科A"));
        exchange2.Instruments.Add(new InstrumentViewModel("SZSE", "000001", "平安银行"));
        exchange2.Instruments.Add(new InstrumentViewModel("SZSE", "000623", "吉林敖东"));
        exchange2.Instruments.Add(new InstrumentViewModel("SZSE", "002739", "万达电影"));
        exchange2.Instruments.Add(new InstrumentViewModel("SZSE", "300642", "透景生命"));


        Exchanges.Add(exchange1);
        Exchanges.Add(exchange2);
    }

    public string BindData { get; set; } = "BindData";
    public ObservableCollection Exchanges { get; set; }
}