窗口中的小复杂数据绑定形成组合框 [英] Little complex databinding in windows form combobox

问题描述

我在Windows窗体中处理数据绑定时遇到了麻烦。我有两个类，一个是Project，另一个是Update。现在所有项目对象都有一个更新列表，它被绑定到一个组合框，但是当用户更改选择时需要显示/绑定Update对象的属性到另一个控件。但是，当用户更改选择时，不会按预期更新。请帮帮我。



我尝试过：

I am in trouble while working on Databinding in windows form. I have two classes, one is Project and another is Update. Now all project object is having a list of Updates and it is binded to a combobox, but when the user changes selection need to display/bind the properties of Update object to another controls. But is not updating as expected, when the user changes selection. Please help me on this.

What I have tried:

public class Project
{
    private int _id;
    private string _name;

    public Project(int id, string name)
    {
        _id = id;
        _name = name;

        ReadUpdates();
    }

    public List<Update> AvailableUpdates { get; set; }
    public int Id { get { return _id; } }

    public string ProjName
    {
        get { return _name; }
        set { _name = value; }
    }

    private void ReadUpdates()
    {
        AvailableUpdates = new List<Update>();

        for (int i = 0; i < 10; i++)
        {
            AvailableUpdates.Add(new
                Update(i, DateTime.Now.AddDays(i)));
        }
    }
}

public class Update
{
    private string _title;
    private int _uid;
    private DateTime _updatedOn;

    public Update(int id, DateTime updatedOn)
    {
        _title = $"Update:{id}";
        _uid = id;
        _updatedOn = updatedOn;
    }

    public string Title
    {
        get { return _title; }
        set { _title = value; }
    }

    public int UId
    {
        get { return _uid; }
        set { _uid = value; }
    }

    public DateTime UpdatedOn
    {
        get { return _updatedOn; }
        set { _updatedOn = value; }
    }
}

public partial class Form1 : Form
{
    private Update _currentUpdate;
    private Project _project;

    public Form1()
    {
        InitializeComponent();

        _project = new Project(1, "Sample Project");

        DoBindings();
    }

    private void DoBindings()
    {
        NameBox.DataBindings.Add("Text", _project, "ProjName");
        IdBox.DataBindings.Add("Text", _project, "Id");

        UpdatesCombo.DataSource = _project.AvailableUpdates;
        UpdatesCombo.DisplayMember = "UId";

        _currentUpdate = (Update)UpdatesCombo.SelectedItem;

        UpdateTitle.DataBindings.Add("Text", _currentUpdate, "Title");
        UpdateDate.DataBindings.Add("Value", _currentUpdate, "UpdatedOn");
    }

    private void UpdatesCombo_SelectionChangeCommitted(object sender, System.EventArgs e)
    {
        _currentUpdate = (Update)UpdatesCombo.SelectedItem;
    }
}

推荐答案

更新：{id};
_uid = id;
_updatedOn = updatedOn;
}

公共字符串标题
{
get {return _title; }
set {_title = value; }
}

public int UId
{
get {return _uid; }
set {_uid = value; }
}

public DateTime UpdatedOn
{
get {return _updatedOn; }
set {_updatedOn = value; }
}
}

公共部分类Form1：表格
{
private Update _currentUpdate;
private Project _project;

public Form1（）
{
InitializeComponent（）;

_project = new Project（1，Sample Project）;

DoBindings（）;
}

private void DoBindings（）
{
NameBox.DataBindings.Add（Text，_ project，ProjName）;
IdBox.DataBindings.Add（Text，_ project，Id）;

UpdatesCombo.DataSource = _project.AvailableUpdates;
UpdatesCombo.DisplayMember =UId;

_currentUpdate =（Update）UpdatesCombo.SelectedItem;

UpdateTitle.DataBindings.Add（Text，_ currentUpdate，Title）;
UpdateDate.DataBindings.Add（Value，_ currentUpdate，UpdatedOn）;
}

private void UpdatesCombo_SelectionChangeCommitted（object sender，System.EventArgs e）
{
_currentUpdate =（Update）UpdatesCombo.SelectedItem;
}
}

"Update:{id}"; _uid = id; _updatedOn = updatedOn; } public string Title { get { return _title; } set { _title = value; } } public int UId { get { return _uid; } set { _uid = value; } } public DateTime UpdatedOn { get { return _updatedOn; } set { _updatedOn = value; } } } public partial class Form1 : Form { private Update _currentUpdate; private Project _project; public Form1() { InitializeComponent(); _project = new Project(1, "Sample Project"); DoBindings(); } private void DoBindings() { NameBox.DataBindings.Add("Text", _project, "ProjName"); IdBox.DataBindings.Add("Text", _project, "Id"); UpdatesCombo.DataSource = _project.AvailableUpdates; UpdatesCombo.DisplayMember = "UId"; _currentUpdate = (Update)UpdatesCombo.SelectedItem; UpdateTitle.DataBindings.Add("Text", _currentUpdate, "Title"); UpdateDate.DataBindings.Add("Value", _currentUpdate, "UpdatedOn"); } private void UpdatesCombo_SelectionChangeCommitted(object sender, System.EventArgs e) { _currentUpdate = (Update)UpdatesCombo.SelectedItem; } }

使用BindingList< t>而不是List< t>和一个BindingSource，它将按照需要工作

use a BindingList<t> instead of List<t> and a BindingSource and it will work as desired

using System.ComponentModel;

public partial class Form1 : Form
  {
    private Update _currentUpdate;
    private Project _project;
    private BindingSource bs;
    ...
    private void DoBindings()
    {
      NameBox.DataBindings.Add("Text", _project, "ProjName");
      IdBox.DataBindings.Add("Text", _project, "Id");

      bs = new BindingSource();
      bs.DataSource = _project.AvailableUpdates;
      UpdatesCombo.DataSource = bs;
      UpdatesCombo.DisplayMember = "UId";
      UpdatesCombo.ValueMember = "UId";

      _currentUpdate = (Update)UpdatesCombo.SelectedItem;

      UpdateTitle.DataBindings.Add("Text", bs, "Title");
      UpdateDate.DataBindings.Add("Value", bs, "UpdatedOn");
    }

  }


  public class Project 
  {
     //...
     public BindingList<Update> AvailableUpdates { get; set; }

  }

  //...
  private void ReadUpdates()
      {
        AvailableUpdates = new BindingList<Update>();

        for (int i = 0; i < 10; i++)
        {
          AvailableUpdates.Add(new
              Update(i, DateTime.Now.AddDays(i)));
        }
      }

你会在这里找到一个非常相似的问题的更详细的答案：

C＃ - 组合框除非您先更改选择，否则不会更新其显示列表 - Stack Overflow [ ^ ]

这篇关于窗口中的小复杂数据绑定形成组合框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！