c# - 数据绑定(bind)问题

Question

我在将我的数据从 TextBox 绑定(bind)到 ViewModel 到 TextBlock 时遇到了一个主要问题。我已经像这样设置了以下 Xaml 代码:

<Page
x:Class="digiBottle.MainPage"
DataContext="{Binding Source=UserProfile}"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:digiBottle"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}" 
      DataContext="{Binding Source=UserProfile}">

    <TextBlock HorizontalAlignment="Left" Margin="219,72,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Height="32" Width="232" Text="{Binding userFirstName, Mode=OneWay}"/>
    <TextBox HorizontalAlignment="Left" Margin="39,72,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="111" Text="{Binding userFirstName, UpdateSourceTrigger=PropertyChanged}"/>

</Grid>

我尝试用作源的 .cs 文件定义如下:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace digiBottle.Model

{ 公共(public)类 UserProfile:INotifyPropertyChanged {

    public int ID { get; set; }
    public string userFirstName;
    public string userLastName { get; set; }
    public int age { get; set; }
    public int weight { get; set; }
    public int height { get; set; }
    public DateTime signupTime { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;

    public UserProfile()
    {
        userFirstName = "First Name";
    }


    private void RaisePropertyChanged(string propertyName)
    {
        if (this.PropertyChanged != null)
        {
            this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

    }

    public UserProfile getCopy()
    {
        UserProfile copy = (UserProfile)this.MemberwiseClone();
        return copy;
        }
    }
}

尝试将我的 TextBox 和 TextBlock 绑定(bind)到 UserProfile.cs 源中的 userFirstName 时，我做错了什么。任何帮助都是很大的帮助!

谢谢

Answer 1

我在这里注意到的第一件事是您的属性(setter)没有引发事件变化。您需要在属性 setter 中调用 RaisePropertyChanged。

我会这样写

私有(private)领域

private String _userFirstName;

然后在构造函数中

 public UserProfile()
 {
      this._userFirstName = "First Name";
 }

随着属性(property)筹集事件

public String UserFirstName
{
     get { return this._userFirstName; }
     set  
     {
         this._userFirstName = value;
         this.RaisePropertyChanged("UserFirstName");
     }
}

然后在 XAML 中，通过双向绑定(bind)将其与属性“UserFirstName”绑定(bind)

<TextBlock HorizontalAlignment="Left" Margin="219,72,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Height="32" Width="232" Text="{Binding UserFirstName, Mode=OneWay}"/>
<TextBox HorizontalAlignment="Left" Margin="39,72,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="111" Text="{Binding UserFirstName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>