数据绑定文本框不反映源更改 [英] Databound TextBox doesn't reflect source changes

问题描述

我需要TextBox，它将反映数据绑定字符串中的更改.我尝试了以下代码:

public partial class Form1 : Form
{
    string m_sFirstName = "Brad";
    public string FirstName
    {
        get { return m_sFirstName; }
        set { m_sFirstName = value; }
    }

    public Form1()
    {
        InitializeComponent();

        textBox1.DataBindings.Add("Text", this, "FirstName");
    }

    private void buttonRename_Click(object sender, EventArgs e)
    {
        MessageBox.Show("before: " + FirstName);
        FirstName = "John";
        MessageBox.Show("after: " + FirstName);
    }
}

启动应用程序后，brad会正确填充textBox1. 我单击按钮"，将"FirstName"重命名为"John"(第二个消息框对此进行了确认). 但是textBox1仍然充满Brad，而不是John.为什么?什么会使这项工作?

解决方案

之所以DataBinding无法反映您的更改，是因为您绑定了一个简单的System.String对象，该对象尚未设计成在修改时会引发事件. /p>

因此，您有2个选择.一种是在按钮的Click事件中重新绑定值(请避免！).另一种方法是创建一个自定义类，该类将实现INotifyPropertyChanged，如下所示:

public partial class Form1 : Form
{
    public Person TheBoss { get; set; }

    public Form1()
    {
        InitializeComponent();

        TheBoss = new Person { FirstName = "John" };

        textBox1.DataBindings.Add("Text", this, "TheBoss.FirstName");
    }

    private void button1_Click(object sender, EventArgs e)
    {
        TheBoss.FirstName = "Mike";
    }


    public class Person : INotifyPropertyChanged
    {
        private string firstName;

        public string FirstName
        {
            get 
            { 
                return firstName; 
            }
            set 
            { 
                firstName = value;
                NotifyPropertyChanged("FirstName");
            }
        }

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }
}

INotifyPropertyChanged文档: MSDN

I need TextBox which will reflect changes in databound string. I tried following code:

public partial class Form1 : Form
{
    string m_sFirstName = "Brad";
    public string FirstName
    {
        get { return m_sFirstName; }
        set { m_sFirstName = value; }
    }

    public Form1()
    {
        InitializeComponent();

        textBox1.DataBindings.Add("Text", this, "FirstName");
    }

    private void buttonRename_Click(object sender, EventArgs e)
    {
        MessageBox.Show("before: " + FirstName);
        FirstName = "John";
        MessageBox.Show("after: " + FirstName);
    }
}

After launching an application, textBox1 is correctly filled with Brad. I clicked the Button, it renamed FirstName to "John" (second messagebox confirms it). But the textBox1 is still filled with Brad, not with John. Why? What will make this work?

解决方案

The reason why the DataBinding is not reflecting your changes is because you are binding a simple System.String object which have not been designed to throw events when modified.

So you have 2 choices. One is to rebind the value when in the Click event of your button (please avoid!). The other is to make a custom class that will implement INotifyPropertyChanged like this:

public partial class Form1 : Form
{
    public Person TheBoss { get; set; }

    public Form1()
    {
        InitializeComponent();

        TheBoss = new Person { FirstName = "John" };

        textBox1.DataBindings.Add("Text", this, "TheBoss.FirstName");
    }

    private void button1_Click(object sender, EventArgs e)
    {
        TheBoss.FirstName = "Mike";
    }


    public class Person : INotifyPropertyChanged
    {
        private string firstName;

        public string FirstName
        {
            get 
            { 
                return firstName; 
            }
            set 
            { 
                firstName = value;
                NotifyPropertyChanged("FirstName");
            }
        }

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }
}

INotifyPropertyChanged documentation : MSDN

这篇关于数据绑定文本框不反映源更改的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！