以mvvm模式在wpf中绑定数据 [英] Data binding in wpf in mvvm pattern

问题描述

如何使用mvvm模式在组合框中使用wpf进行数据绑定。和数据绑定区域中的初学者

解决方案

最好的办法是在ViewModel中使用 CollectionView ，然后绑定你的ComboBox到CollectionView。 CollectionView有一个CurrentChanged事件，您可以使用它来处理用户选择更改，如下所示（假设您的ComboBox项目存储在List< string>中）

  class  YourWindowViewModel 
 {
  public  CollectionView comboBoxItems {获取;  private   set ; } 
 
  public  YourWindowViewModel（）
 {
  //   ComboBox的原始列表 
 IList< string> ComboBoxList =  new  List< string>（）; 
 
 comboBoxItems =  new  CollectionView（ComboBoxList）; 
 comboBoxItems.MoveCurrentTo（ComboBoxList [ 0 ]）; 
 comboBoxItems.CurrentChanged + =  new  EventHandler（comboBox_CurrentChanged）; 
} 
 
  void  comboBox_CurrentChanged（ object  sender，EventArgs e） 
 {
  //  如果选择更改，请在此处工作 
} 
} 

希望这有帮助

我建​​议使用一个可观察的属性您的Viewmodel：

 私人 CollectionView _comboBoxOptions = 空; 
  public  CollectionView comboBoxOptions 
 {
  get  { return  _comboBoxOptions; } 
  set  
 {
  if （_ comboBoxOptions！=  value ）
 {
 _comboBoxOptions =  value ; 
 RaisePropertyChanged（  comboBoxOptions）; 
} 
} 
} 

您还必须在Viewmodel中使用INotifyPropertyChanged：< br $> b $ b

  public   event  PropertyChangedEventHandler PropertyChanged; 
  protected   void  RaisePropertyChanged（ string  name）
 {
 PropertyChangedEventHandler handler = PropertyChanged; 
  if （handler！=  null ）handler（ this ， new  PropertyChangedEventArgs（name））; 
} 

然后在您的XAML中将您的控件绑定到该属性：

 <   ComboBox  >  
 <   Binding    路径  =  comboBoxOptions  
   
         ValidatesOnDataErrors  < span class =code-keyword> =  True  
  < span class =code-attribute> 
         NotifyOnValidationError   =  True  
   
  < span class =code-attribute>      模式  =  OneWay  
   
         UpdateSourceTrigger   =  LostFocus  /  >  
 <   / ComboBox  >  

您可以在Viewmodel的构造函数中初始化comboBoxOptions属性。



希望这有帮助



劳伦斯

你好

查看此代码，它可能对您有帮助。

  public   class 订单
 {
  private   readonly   string  _instrument; 
  private   readonly   double  _price ; 
  private   readonly   long  _quantity ; 
 
  public 订单（字符串工具，双价格，长数量）
 {
 _instrument = instrument; 
 _price = price; 
 _quantity =数量; 
} 
 
  public   string 工具
 {
  get  { return  _instrument; } 
} 
 
  public   double 价格
 { 
 获取 {返回 _price; } 
} 
 
  public   long 数量
 { 
  get  { return  _quantity; } 
} 
} 
 
  public   void  PopulateGrid （网格）
 {
 BindingList< order> orders =  new  BindingList< order>（）; 
 
 orders.Add（ new 订单（  Instrument1， 10 。 55 ， 34 ））; 
 orders.Add（ new 订单（  Instrument2， 12 。 26 ， 154 ））; 
 orders.Add（ new 订单（  Instrument1， 13 。 16 ， 14 ））; 
 orders.Add（ new 订单（  Instrument5， 9 。 85 ， 52 ））; 
 orders.Add（ new 订单（  Instrument1， 16 。 47 ， 11 ））; 
 
 grid.DataSource = orders; 
} 
 < /  订单 >  < /  订单 > ;  

更多信息可以在这里找到 http://www.dapfor.com/en/net-suite/net-grid/features/hierarchical-data-binding [< a href =http://www.dapfor.com/en/net-suite/net-grid/features/hierarchical-data-binding\"target =_ blanktitle =New Window> ^ ]

how to do data binding in wpf for combobox ia m using mvvm pattern. and beginner in data binding area

解决方案

Your best bet is to use a CollectionView in your ViewModel, and bind your ComboBox to the CollectionView. The CollectionView has a CurrentChanged event which you can use to act on user selection changes, something like this (assuming your ComboBox Items are stored in a List<string>)

class YourWindowViewModel
    {
        public CollectionView comboBoxItems { get; private set; }

        public YourWindowViewModel()
        {
            //Original list for ComboBox
            IList<string> ComboBoxList = new List<string>();
 
            comboBoxItems = new CollectionView(ComboBoxList);
            comboBoxItems.MoveCurrentTo(ComboBoxList[0]);
            comboBoxItems.CurrentChanged += new EventHandler(comboBox_CurrentChanged);
        }
 
        void comboBox_CurrentChanged(object sender, EventArgs e)
        {
            //Do work here if selection changes
        }
    }

Hope this helps

I would suggest using an observable property in your Viewmodel:

private CollectionView _comboBoxOptions = null;
        public CollectionView comboBoxOptions
        {
            get { return _comboBoxOptions; }
            set
            {
                if (_comboBoxOptions != value)
                {
                    _comboBoxOptions = value;
                    RaisePropertyChanged("comboBoxOptions");
                }
            }
        }

You would also have to use INotifyPropertyChanged in the Viewmodel:

public event PropertyChangedEventHandler PropertyChanged;
        protected void RaisePropertyChanged(string name)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(name));
        }

Then in your XAML bind your control to that property :

<ComboBox>
   <Binding Path="comboBoxOptions"

   ValidatesOnDataErrors="True"

   NotifyOnValidationError="True"

   Mode="OneWay"

   UpdateSourceTrigger="LostFocus"/>
</ComboBox>

You could initialise the comboBoxOptions property in the constructor for your Viewmodel.

Hope this helps

Laurence

Hello
have a look on this code, it may help you.

public class Order
{
    private readonly string _instrument;
    private readonly double _price;
    private readonly long _quantity;

    public Order(string instrument, double price, long quantity)
    {
        _instrument = instrument;
        _price = price;
        _quantity = quantity;
    }

    public string Instrument
    {
        get { return _instrument; }
    }

    public double Price
    {
        get { return _price; }
    }

    public long Quantity
    {
        get { return _quantity; }
    }
}

public void PopulateGrid(Grid grid)
{
    BindingList<order> orders = new BindingList<order>();

    orders.Add(new Order("Instrument1", 10.55, 34));
    orders.Add(new Order("Instrument2", 12.26, 154));
    orders.Add(new Order("Instrument1", 13.16, 14));
    orders.Add(new Order("Instrument5", 9.85, 52));
    orders.Add(new Order("Instrument1", 16.47, 11));

    grid.DataSource = orders;
}
</order></order>

more can be found here http://www.dapfor.com/en/net-suite/net-grid/features/hierarchical-data-binding[^]

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