每当我尝试运行我的应用程序时都会收到错误，因为我没有获得comboBox.SelectedValue的实际值，而是获得DataRowView项。
以下是我收到错误的代码：
private void InitDataGridView()
{
query = "SELECT p.name, p.age FROM Person p INNER JOIN Class c ON p.idC=c.idC WHERE p.id="
+ comboBoxClass.SelectedValue;
command = new SqlCommand(query, connection);
adapter = new SqlDataAdapter(command);
datatable = new DataTable();
adapter.Fill(datatable);
dataGridViewStudents.DataSource = datatable;
}
comboBoxClass.SelectedValue应该返回"idC"，因为我设置了DataSource，DisplayMember和（ValueMember -> idC）。
idC是主键（int）。
ComboBox设置：
comboBoxClass.DataSource = datatable;
comboBoxClass.DisplayMember = "className";
comboBoxClass.ValueMember = "idC";
答案 0 :(得分：0)
不绑定或不正确地绑定ValueMember可以产生您描述的确切效果。正如您在下面的代码片段中看到的那样。
在ComboBox的初始化上加上一些断点，并弄清楚为什么ValueMember不是你需要的。然后你的DataGridView应该正确填充。
using System;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
namespace BindingToDataTable_46914296
{
public partial class Form1 : Form
{
ComboBox combob = new ComboBox();
ComboBox combobFail = new ComboBox();
TextBox txtbx = new TextBox();
public Form1()
{
InitializeComponent();
InitComboBox();
InitComboBoxFail();
InitTxtBx();
}
private void InitTxtBx()
{
txtbx.Location = new Point(5, 30);
txtbx.Width = this.Width - 10;
this.Controls.Add(txtbx);
}
/// <summary>
/// This version works, the proper selected value shows up in the textbox
/// </summary>
private void InitComboBox()
{
combob.Location = new Point(5,5);
this.Controls.Add(combob);
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("Col1", typeof(string)));
dt.Columns.Add(new DataColumn("Col2", typeof(string)));
dt.Columns.Add(new DataColumn("Col3", typeof(string)));
dt.Columns.Add(new DataColumn("Col4", typeof(Int32)));
dt.Rows.Add("blah1", "bleh", "bloh", 1);
dt.Rows.Add("blah2", "bleh", "bloh", 2);
dt.Rows.Add("blah3", "bleh", "bloh", 3);
dt.Rows.Add("blah4", "bleh", "bloh", 4);
combob.DataSource = dt;
combob.DisplayMember = "Col1";
combob.ValueMember = "Col4";
combob.SelectedValueChanged += Combob_SelectedValueChanged;
}
/// <summary>
/// This version DOES NOT work, a DataRowView item appears in the textbox when the selection changes
/// </summary>
private void InitComboBoxFail()
{
combobFail.Location = new Point(combob.Location.X + combob.Width + 5, 5);
this.Controls.Add(combobFail);
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("Col1", typeof(string)));
dt.Columns.Add(new DataColumn("Col2", typeof(string)));
dt.Columns.Add(new DataColumn("Col3", typeof(string)));
dt.Columns.Add(new DataColumn("Col4", typeof(Int32)));
dt.Rows.Add("blah1", "bleh", "bloh", 1);
dt.Rows.Add("blah2", "bleh", "bloh", 2);
dt.Rows.Add("blah3", "bleh", "bloh", 3);
dt.Rows.Add("blah4", "bleh", "bloh", 4);
combobFail.DataSource = dt;
combobFail.DisplayMember = "Col1";
//only difference is I am not binding ValueMember
combobFail.SelectedValueChanged += Combob_SelectedValueChanged;
}
private void Combob_SelectedValueChanged(object sender, EventArgs e)
{
txtbx.Text = ((ComboBox)sender).SelectedValue.ToString();
}
}
}
答案 1 :(得分：0)
好的，我发现我的代码出了什么问题。它既不是<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
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<br>
<button id = "btn">animate</button>初始化也不是comboBox，但写下错误查询完全是我的错。
我感谢大家帮助我的努力。