ASP .NET RowUpdating GridView 问题

Question

我在使用

RowUpdating

方法时遇到问题。我的

GridView

已连接到本地 SQL Server，我正在尝试更新数据。以下是来自 MSDN 的

RowUpdating

方法的代码。

protected void TaskGridView_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
        //Retrieve the table from the session object.
        DataTable dt = (DataTable)Session["TaskTable"];

        //Update the values.
        GridViewRow row = GridView1.Rows[e.RowIndex];
        dt.Rows[row.DataItemIndex]["Id"] = ((TextBox)(row.Cells[1].Controls[0])).Text;
        dt.Rows[row.DataItemIndex]["Description"] = ((TextBox)(row.Cells[2].Controls[0])).Text;
        dt.Rows[row.DataItemIndex]["IsComplete"] = ((CheckBox)(row.Cells[3].Controls[0])).Checked;

        //Reset the edit index.
        GridView1.EditIndex = -1;

        //Bind data to the GridView control.
        BindData();

}

我收到此错误：

System.NullReferenceException：未将对象引用设置为对象的实例。

Answer 1

尝试此代码一次。

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
    int id = Int32.Parse(GridView1.DataKeys[e.RowIndex].Value.ToString());
    TextBox tname = (TextBox)row.FindControl("nam");
    TextBox tques = (TextBox)row.FindControl("que");
    MySqlCommand cmd = new MySqlCommand("update exam set name1=@name,ques=@ques where id = @id", con);
    cmd.Parameters.Add("@id", MySqlDbType.Int16).Value = id;
    cmd.Parameters.Add("@name", MySqlDbType.VarChar, 30).Value = tname.Text.Trim();
    cmd.Parameters.Add("@ques", MySqlDbType.VarChar,40).Value = tques.Text.Trim();
    con.Open();
    cmd.ExecuteNonQuery();
    GridView1.EditIndex = -1;
    bind();
}

Answer 2

并非所有 GridViewRow 都有 DataItem。

您应该在代码周围添加一个

if

块，并验证正在更新的行的类型为

DataRow

。

if (e.Row.RowType == DataControlRowType.DataRow)
{
     your code here...
}

有关 RowType 的更多信息：http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridviewrow.rowtype.aspx

Answer 3

public void bindGvEdit()
{
    GridView1.DataSource = obj1.SelectAlltbl();
    GridView1.DataBind();
}

protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
    GridView1.EditIndex = e.NewEditIndex;
    bindGvEdit();
}

protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
    GridView1.EditIndex = -1;
    bindGvEdit();
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = GridView1.Rows[e.RowIndex];
    obj1.Id = Convert.ToInt32(GridView1.DataKeys[row.RowIndex].Value);
    obj1.Name = ((TextBox)row.Cells[1].Controls[1]).Text;
    obj1.Description = ((TextBox)row.Cells[2].Controls[1]).Text;
    obj1.Updatetbl();
    GridView1.EditIndex = -1;
    bindGvEdit();
}

Answer 4

protected void GridView1_RowUpdating（对象发送者，GridViewUpdateEventArgs e） { DataRow[] dr = dt.Select("id=" + Convert.ToInt32(GridView1.Rows[e.RowIndex].Cells[0].Text)); dr[0][1] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text; dr[0][2] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text; dr[0][3] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[3].Controls[0]).Text; dr[0][4] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[4].Controls[0]).Text; dr[0][5] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[5].Controls[0]).Text; dr[0][6] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[6].Controls[0]).Text; dr[0][7] = ((TextBox)GridView1.Rows[e.RowIndex].Cells[7].Controls[0]).Text; adp.Update(dt); 展示（）; }

我收到此错误 - System.FormatException：“输入字符串的格式不正确。”