通过 asp.net 中的保存按钮将数据绑定到 gridview 后，保存按钮单击事件会在刷新页面时触发

Question

我正在使用 C# 和 ASP.NET 开发 Web 应用程序。我通过同一页面中的文本框将数据绑定到 gridview，并在“保存”按钮单击事件中编写了绑定方法。

现在，当我通过“save”button_click 事件将数据从文本框保存到 gridview 并刷新页面时，发现网格视图再次与重复行绑定，这真的很奇怪。我尝试在 firefox、chrome 和 IE 8 上加载页面...但结果是否定的...

任何人都可以让我知道为什么会发生并指导我解决它...

这是我的 C# 代码:

string con = ConfigurationSettings.AppSettings["ConnectionStrings"];

protected void Page_Load(对象发送者, EventArgs e) {

    tbladdasset.Visible = false;
    btnsaveasset.Enabled = false;
    lblErrMsg.Text = "";

    if (!IsPostBack)
    {
        bindassets("", "");
        ViewState["sortOrder"] = "";
    }
}

private void bindassets(string sortExp, string sortDir)
{
    try
    {
        SqlConnection con1 = new SqlConnection(con);
        con1.Open();
        SqlCommand cmd = new SqlCommand("select Description,CONVERT(VARCHAR(10), RecievedDate, 101) as DateRecieved,cost,Modelno,Quantity from Asset", con1);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);
        con1.Close();

        if (dt.Rows.Count > 0)
        {
            DataView dv = dt.DefaultView;

            if (sortExp != string.Empty)
            {
                dv.Sort = string.Format("{0} {1}", sortExp, sortDir);
            }

            grdvAssets.DataSource = dv;
            grdvAssets.DataBind();

        }
        else
        {
            lblErrMsg.Text = "No data found...";
        }

        btnsaveasset.Enabled = false;
        tbladdasset.Visible = false;
    }
    catch
    {
        lblErrMsg.Text = "Failed to connect server...";
    }
}

protected void btnaddnew_Click(object sender, EventArgs e)
{
    tbladdasset.Visible = true;
    btnsaveasset.Enabled = true;
    lblErrMsg.Text = "";
    txtdescription.Text = "";
    txtdtrecieved.Text = "";
    txtcost.Text = "";
    txtmodelno.Text = "";
    txtquantity.Text = "";
}

protected void btnsaveasset_Click(object sender, EventArgs e)
{
        if (txtdescription.Text != "" && txtdtrecieved.Text != "" && txtcost.Text != "" && txtmodelno.Text != "" && txtquantity.Text != "")
        {
            try
            {
                string desc= txtdescription.Text;
                DateTime dtrecd = Convert.ToDateTime(txtdtrecieved.Text);
                string cost = txtcost.Text;
                string modelno = txtmodelno.Text;
                double quantity = Convert.ToDouble(txtquantity.Text);
                SqlConnection sqlcon = new SqlConnection(con);
                sqlcon.Open();
                string save = "Insert into Asset(Description,Recieveddate,cost,Modelno,Quantity)values(@desc,@date,@cost,@modelno,@quantity)";
                SqlCommand cmd = new SqlCommand(save, sqlcon);
                cmd.CommandType = CommandType.Text;
                cmd.Parameters.Add("@desc", desc);
                cmd.Parameters.Add("@date", dtrecd);
                cmd.Parameters.Add("@cost", cost);
                cmd.Parameters.Add("@modelno", modelno);
                cmd.Parameters.Add("@quantity", quantity);
                cmd.ExecuteNonQuery();
                sqlcon.Close();
                bindassets("", "");
                btnsaveasset.Enabled = false;
                txtdescription.Text = "";
                txtdtrecieved.Text = "";
                txtcost.Text = "";
                txtmodelno.Text = "";
                txtquantity.Text = "";
                lblErrMsg.Text = "data inserted successfully..";
            }
            catch
            {
                lblErrMsg.Text = "Please enter valid data and try again...";
            }
        }
        else
        {
            lblErrMsg.Text = "Please enter valid data and try again...";
        }

}

protected void grdvAssets_Sorting(object sender, GridViewSortEventArgs e)
{
    bindassets(e.SortExpression, sortOrder);
}

public string sortOrder
{
    get
    {
        if (ViewState["sortOrder"].ToString() == "desc")
        {
            ViewState["sortOrder"] = "asc";
        }
        else
        {
            ViewState["sortOrder"] = "desc";
        }

        return ViewState["sortOrder"].ToString();
    }
    set
    {
        ViewState["sortOrder"] = value;
    }
}

任何人请帮助我......提前致谢..

Answer 1

这是一个常见问题。检查类似的SO问题：Webforms刷新问题，如何停止不需要的回发。

如果有几个词，网络浏览器刷新按钮只是将最后一个请求发送到服务器，在您的情况下，这是一个“保存”按钮单击事件，因此它会给出重复的行。使用Response.Redirect，这个这样最后一个请求只是导航到页面，因此刷新不会造成不良影响。

已编辑

我看到您添加了一些代码。这是为您提供的解决方法。将数据保存到数据库这一事实有很大帮助。页面加载事件的第一件事不需要检查页面是否IsPostBack，只需调用 bindassets("", ""); 方法。

至于保存按钮单击事件。无需调用 bindassets("", ""); 它将在页面加载时调用。

protected void btnsaveasset_Click(object sender, EventArgs e)
{
        if (txtdescription.Text != "" && txtdtrecieved.Text != "" && txtcost.Text != "" && txtmodelno.Text != "" && txtquantity.Text != "")
        {
            try
            {
                string desc= txtdescription.Text;
                DateTime dtrecd = Convert.ToDateTime(txtdtrecieved.Text);
                string cost = txtcost.Text;
                string modelno = txtmodelno.Text;
                double quantity = Convert.ToDouble(txtquantity.Text);
                SqlConnection sqlcon = new SqlConnection(con);
                sqlcon.Open();
                string save = "Insert into Asset(Description,Recieveddate,cost,Modelno,Quantity)values(@desc,@date,@cost,@modelno,@quantity)";
                SqlCommand cmd = new SqlCommand(save, sqlcon);
                cmd.CommandType = CommandType.Text;
                cmd.Parameters.Add("@desc", desc);
                cmd.Parameters.Add("@date", dtrecd);
                cmd.Parameters.Add("@cost", cost);
                cmd.Parameters.Add("@modelno", modelno);
                cmd.Parameters.Add("@quantity", quantity);
                cmd.ExecuteNonQuery();
                sqlcon.Close();
                //bindassets("", "");
                btnsaveasset.Enabled = false;
                txtdescription.Text = "";
                txtdtrecieved.Text = "";
                txtcost.Text = "";
                txtmodelno.Text = "";
                txtquantity.Text = "";
                lblErrMsg.Text = "data inserted successfully..";

            }
            catch
            {
                lblErrMsg.Text = "Please enter valid data and try again...";
            }
        }
        else
        {
            lblErrMsg.Text = "Please enter valid data and try again...";
        }
        Response.Redirect("nameofpage.aspx", false);//does a charm. browser refresh button will repeat last action and from now on that's a Response.Redirect("nameofpage.aspx", false). thus no duplicate records
}

Answer 2

if (!IsPostBack)
{
    Bind(); //bind data to grid
}