绑定到对象属性 [英] binding to an object properties

问题描述

方案是将article对象的WordsNum属性绑定到文本块，以便在属性更改时更新它。我花了好几个小时来调试它，但这似乎是一个丑陋的错误！

 <   Window     x：Class   =  Article_Word_Counter.MainWindow  
   
                   xmlns   =  http://schemas.microsoft.com/winfx/2006/xaml/presentation  
   
                   xmlns：x   =  http://schemas.microsoft.com/winfx/2006/xaml  
   
                  标题  =  MainWindow   高度  =  350   宽度  =  525    FontSize   =  14 >  
 <  网格 >  
 <   StackPanel  >  
 < ;  标签 > 选择您的文章： <   / Label  >  
 <   TextBox    名称  =  txtFilePath   高度  =  30 >  <   / TextBox  >  
 <  按钮   名称  =  btnBrowse   高度  =  30   宽度  =  150   点击  =  btnBrowse_Click > 浏览<   /按钮 >  
 <   GroupBox    标题  = 文章信息 >  
 <   StackPanel  >  
 <   StackPanel    方向  = 水平 >  
 <  标签 > 字数：<   / Label  >  
 <   TextBlock    文本  =  {Binding Path = WordsNum，UpdateSourceTrigger = PropertyChanged} >  <   / TextBlock  >  
 <   / StackPanel  >  
 
 <   / StackPanel  >  
 <   / GroupBox  >  
 <   / StackPanel  >  
 <   / Grid  >  
 <   / Window  >  

< pre lang =c＃> 命名空间 Article_Word_Cou nter
{
public partial class MainWindow：Window
{
public 文章CurrentArticle { get ; set ; }
public MainWindow（）
{
InitializeComponent（）;
base .DataContext = CurrentArticle;
}

private void btnBrowse_Click（ object sender，RoutedEventArgs e）
{
// openfiledialog的逻辑
// strFilePath是从逻辑上获得的
CurrentArticle = new Article（strFilePath）;
}
}
public class 文章：INotifyPropertyChanged
{
private int wordsNum;
public int WordsNum
{
获取
{
return wordsNum;
}
set
{
wordsNum = value ;
this .OnPropertyChanged（ WordsNum< /跨度>）;
}
}

#region ctors
// public
public 文章（ string strFilePath）
{
// 计算逻辑intCount
WordsNum = intCount;
}

#endregion

#region INotifyPropertyChanged成员

public event PropertyChangedEventHandler PropertyChanged;

void OnPropertyChanged（ string propName）
{
if （ this .PropertyChanged！= null ）
this .PropertyChanged（ this ，新 PropertyChangedEventArgs（propName））;
}

#endregion
}
}

解决方案

在 btnBrowse_Click 中设置 CurrentArticle 但 DataContext 仍保留旧值...

您可以设置 DataContext ：

  private   void  btnBrowse_Click（ object  sender，RoutedEventArgs e）
 {
  //   openfiledialog的逻辑 
  //   strFilePath是从上面的逻辑中获得的 
 CurrentArticle =  new  Article（strFilePath）; 
  DataContext = CurrentArticle;  
} 
 




The scenario is to bind the WordsNum property of article object to a textblock so that it is updated when the property changes. I have spent hours on debugging this but it seems to be an ugly error!


<Window x:Class="Article_Word_Counter.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        Title="MainWindow" Height="350" Width="525" FontSize="14">
    <Grid>
        <StackPanel>
            <Label>Choose your article:</Label>
            <TextBox Name="txtFilePath" Height="30"></TextBox>
            <Button Name="btnBrowse" Height="30" Width="150" Click="btnBrowse_Click">Browse</Button>
            <GroupBox Header="Article Info"> 
                <StackPanel>
                    <StackPanel Orientation="Horizontal">
                        <Label>Numder of Words: </Label>
                        <TextBlock Text="{Binding Path=WordsNum, UpdateSourceTrigger=PropertyChanged}"></TextBlock> 
                    </StackPanel>
                    
                </StackPanel>
            </GroupBox>
        </StackPanel>
    </Grid>
</Window>





namespace Article_Word_Counter
{
    public partial class MainWindow : Window
    {
        public Article CurrentArticle { get; set; }
        public MainWindow()
        {
            InitializeComponent();
            base.DataContext = CurrentArticle;  
        }

        private void btnBrowse_Click(object sender, RoutedEventArgs e)
        {
            //logic for openfiledialog
            //strFilePath is obtained from above logic
            CurrentArticle = new Article(strFilePath);
        }
    }
    public class Article: INotifyPropertyChanged
    {
        private int wordsNum;
        public int WordsNum 
        {
            get
            {
                return wordsNum;
            }
            set
            {
                wordsNum = value;
                this.OnPropertyChanged("WordsNum");
            }
        }
        
        #region ctors
        //public 
        public Article(string strFilePath)
        {
            //logic for calculatin intCount 
            WordsNum = intCount;
        }

        #endregion

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        void OnPropertyChanged(string propName)
        {
            if (this.PropertyChanged != null)
                this.PropertyChanged(this, new PropertyChangedEventArgs(propName));
        }

        #endregion
    }
}

解决方案

In btnBrowse_Click you set the value of CurrentArticle but the DataContext still keeps the old value...

You can set the DataContext too:

private void btnBrowse_Click(object sender, RoutedEventArgs e)
{
    //logic for openfiledialog
    //strFilePath is obtained from above logic
    CurrentArticle = new Article(strFilePath);
    DataContext = CurrentArticle;
}




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