Question

说实话，这是我第一次看到这样的错误

The 'SelectedIndex' and 'SelectedValue' attributes are mutually exclusive

这是发生错误的地方。它发生在数据绑定。

protected void FillDropdown(DropDownList ddl)
{
    using (var connAdd = new SqlConnection("Data Source = localhost; Initial Catalog = MajorProject; Integrated Security= SSPI"))
    {
        connAdd.Open();

        var sql = "Select policeid from PoliceAccount where status ='available' and handle ='offcase' and postedto='" + ddllocation.SelectedValue + "'";
        using (var cmdAdd = new SqlDataAdapter(sql, connAdd))
        {
            DataSet ds2 = new DataSet();
            cmdAdd.Fill(ds2);

            ddl.Items.Clear();
            ddl.DataSource = ds2;
            //error occurs here
            ddl.DataBind();
            ddl.Items.Insert(0, new ListItem("Police ID", ""));
            ddl.SelectedIndex = 0;
        }
    }
}

我不太确定他们为什么会说这样的话。我在下拉列表中使用了这个FillDropdown。

protected void ddlpid1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (ddlpid1.SelectedIndex > 0)
    {
        Session["pid1"] = ddlpid1.SelectedValue;

        ListItem removeItem2 = ddlpid2.Items.FindByValue(ddlpid1.SelectedValue);
        ddlpid2.Items.Remove(removeItem2);
        ListItem removeItem3 = ddlpid3.Items.FindByValue(ddlpid1.SelectedValue);
        ddlpid3.Items.Remove(removeItem3);
        ListItem removeItem4 = ddlpid4.Items.FindByValue(ddlpid1.SelectedValue);
        ddlpid4.Items.Remove(removeItem4);
        ListItem removeItem5 = ddlpid5.Items.FindByValue(ddlpid1.SelectedValue);
        ddlpid5.Items.Remove(removeItem5);
    }
    else if (ddlpid1.SelectedItem.Text.Equals("Police ID"))
    {
        FillDropdown(ddlpid1);
        FillDropdown(ddlpid2);
        FillDropdown(ddlpid3);
        FillDropdown(ddlpid4);
        FillDropdown(ddlpid5);

        ddlpid2.SelectedValue = (String) Session["pid2"];
        ddlpid2_SelectedIndexChanged(this, EventArgs.Empty);

        ddlpid3.SelectedValue = (String) Session["pid3"];
        ddlpid3_SelectedIndexChanged(this, EventArgs.Empty);

        ddlpid4.SelectedValue = (String) Session["pid4"];
        ddlpid4_SelectedIndexChanged(this, EventArgs.Empty);

        ddlpid5.SelectedValue = (String) Session["pid5"];
        ddlpid5_SelectedIndexChanged(this, EventArgs.Empty);
    }
}

我多次查看我的代码，我看到selectedindex和选定值发生冲突。它们都是单独的功能。

Answer 1

在数据绑定之前将SelectedIndex设置为-1它应该有帮助

Answer 2

在ASP.NET Forums - The 'SelectedIndex' and 'SelectedValue' attributes are mutually exclusive上已经提出了类似的问题。

SelectedIndex事件中同时设置SelectedValue和Page_Load属性的原因。

Answer 3

如果在DataBind（）调用

之前设置了selectedValue，也会发生这种情况

Answer 4

检查数据集ds2是否具有值。如果它有一些policeId作为值，则添加这两行并绑定它。

ddl.DataSource = ds2;
ddl.DataTextField = "policeid";
ddl.DataValueField = "policeid";
ddl.DataBind();

Answer 5

你可以在

之前添加它

ddlst.SelectedIndex = -1;
if (ddlst.SelectedValue.Length>0)
{
    ddlst.SelectedValue.Remove(0);
}

'SelectedIndex'和'SelectedValue'属性是互斥的

5 个答案: