c# wpf 将组合框绑定到 SQL Server 数据库

Question

我正在尝试将我的数据库绑定到一个组合框（“ProjectComboBox”），但似乎无法让它工作。我尝试在 XAML 以及后端代码中传递它，但 Combobox 始终为空白。任何帮助将不胜感激。

SQL Server（本地）数据库：“Database1”

数据源：(DataSet1);表：（项目表）；

组合框名称：“ProjectComboBox”

这是我的 XAML 代码：

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApplication1"
    mc:Ignorable="d"
    Title="MainWindow" Height="500" Width="850">
<Grid>
    <ComboBox x:Name="ProjectComboBox"
              ItemsSource="{Binding Path=ProjectTable}"
              DisplayMemberPath="ProjectName" 
              SelectedValuePath="RFIDirectory" 
              HorizontalAlignment="Left" 
              VerticalAlignment="Top" 
              Width="297" Height="26" 
              SelectionChanged="comboBox_SelectionChanged">
    </ComboBox>

这是我的后端代码：

namespace WpfApplication1

public partial class MainWindow : Window
{
    public DataSet1 ProjectTable { get; set; }
    public MainWindow()
    {
        InitializeComponent();

    private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        ProjectComboBox.Items.Clear();

        SqlConnection con = new SqlConnection("Data Source=(local);Initial Catalog=Database1;Integrated Security=True");

        try
        {
            con.Open();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
        try
        {
            SqlDataAdapter ProjectTableTableAdapter = new SqlDataAdapter("SELECT * FROM PROJECTNAME", con);
            DataSet1 ds = new DataSet1();
            ProjectTableTableAdapter.Fill(ds, "t");

            ProjectComboBox.ItemsSource = ds.Tables["t"].DefaultView;
            ProjectComboBox.DisplayMemberPath = "ProjectName";
            ProjectComboBox.SelectedValuePath = "RFIDirectory";

        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }

    }
}

}

Answer 1

1. 您不能直接绑定到 SQL Server 表记录。但是，您可以绑定到表示表记录的对象列表。
2. 正如@Paul Abbott 所提到的，您必须在表单加载后首先初始化组合框项。或者，一种丑陋的做法是添加一个虚拟记录，一旦您选择它，将引发选择更改事件，然后您的代码将执行。

3. 不要为您的连接打开和 sql 数据适配器执行单独的 try-catch 块。这是多余的。

4. 在你的 sql 连接上使用 using 语句来正确关闭和处理之后。

   public MainWindow()
   {
       InitializeComponent();
       UpdateItems(); // Maybe initialize here?
   }
   
   private void comboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
   {
       ProjectComboBox.Items.Clear(); // Remove this. AFAIK, the selected item will be cleared.
       UpdateItems();
   }
   
   private void UpdateItems()
   {
       try
       {
           using(SqlConnection con = new SqlConnection("Data Source=(local);Initial Catalog=Database1;Integrated Security=True"))
           {
               con.Open();
               SqlDataAdapter ProjectTableTableAdapter = new SqlDataAdapter("SELECT * FROM PROJECTNAME", con);
               DataSet1 ds = new DataSet1();
               ProjectTableTableAdapter.Fill(ds, "t");
   
               ProjectComboBox.ItemsSource = ds.Tables["t"].DefaultView;
               ProjectComboBox.DisplayMemberPath = "ProjectName";
               ProjectComboBox.SelectedValuePath = "RFIDirectory";
           }
       }
       catch (Exception ex)
       {
           MessageBox.Show(ex.ToString());
       } 
   }
   
   <ComboBox x:Name="ProjectComboBox"
         ItemsSource="{Binding Path=ProjectTable}" // Not sure of what the impact will be by adding this because you have already defined the item source on your code-behind. I'd prefer you remove this and use XAML binding when you're following a design pattern like MVVM or MVPVM.
         DisplayMemberPath="ProjectName" 
         SelectedValuePath="RFIDirectory" 
         HorizontalAlignment="Left" 
         VerticalAlignment="Top" 
         Width="297" Height="26" 
         SelectionChanged="comboBox_SelectionChanged">
   </ComboBox>