中繼器內DropDownList上的選定值

Question

我在中繼器中添加了一個dropdwonlist。 現在，我需要為我的下拉列表設置一個選定的值。但是我不是很成功。

private void PhysicianSource()
{
    DataSet ds = new DataSet();
    DataTable dt = ds.Tables.Add("Source");
    dt.Columns.Add("ID", Type.GetType("System.String"));
    dt.Columns.Add("Desc", Type.GetType("System.String"));

    Provider oProvider = new Provider();
    List<ProviderLabel> lstprovider = oProvider.RetrievePhysicianList();
    foreach (ProviderLabel item in lstprovider)
    {
        DataRow dr = dt.NewRow();
        dr[0] = item.ProviderCode.ID.ToString();
        dr[1] = item.Name.ToString();
        dt.Rows.Add(dr);
    }

    drpPhysicianCode.DataSource = ds;
    drpPhysicianCode.DataMember = "Source";
    drpPhysicianCode.DataTextField = "ID";
    drpPhysicianCode.DataValueField = "ID";
    drpPhysicianCode.DataBind();
}

asp.net

<asp:Repeater ID="rptrPatientList" runat="server" >
    <HeaderTemplate></HeaderTemplate>
    <ItemTemplate>
        <tr>
            <td class="style2">
            <asp:DropDownList  ID="DropDownList1"
                DataTextField="ID" runat="server"
                DataValueField="Desc"
                SelectedValue='<%# Eval("Code") %>'
                DataSource="ds">
            </asp:DropDownList>
            </td>

            </td>
        </tr>

我的代碼上什么都沒有發生..幫幫我，我只是這個的初學者..非常感謝..

Answer 1

嗨Ian Ace最好稍微修改一下代碼

 <asp:Repeater ID="rptProductList" runat="server" OnItemDataBound="rptProductList_ItemDataBound">
 <ItemTemplate> 
<asp:DropDownList runat="server" ID="MyRepeater" AutoPostBack="true" OnSelectedIndexChanged="DropDownList_SelectedIndexChanged" >
</asp:DropDownList>
 </ItemTemplate>
 </asp:Repeater>

現在，后面的代碼應該是

  protected void Page_Load(object sender, EventArgs e)
  {
     if (!IsPostBack)
    {
       fillRepeater();
    }
  }


}
protected void rptProductList_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DropDownList MyDropDown= (DropDownList)e.Item.FindControl("MyRepeater");
        if (MyDropDown!= null)
        {
           MyDropDown.DataSource =   fillDropDown(MyDropDown);
            MyDropDown.DataBind();
        }
    }
}




 private DataSet fillDropDown(DropDownList dropDown)
    {
     // get  your collection and return.
    }

protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
    DropDownList MyDropDown= (DropDownList)sender;
    string item = MyDropDown.SelectedValue;
}

希望以上示例對您有所幫助。

Answer 2

發生此問題的原因是下拉列表的綁定發生在轉發器控件的綁定之后。 您可以使用HTML5自定義屬性 ，將下拉列表值設置為自定義屬性，然后在對下拉列表進行數據綁定后將其設置為選定值。 我已經使用asp：ObjectDataSource綁定了下拉列表

ASPX

<asp:Repeater ID="rptrPatientList" runat="server" >
    <HeaderTemplate></HeaderTemplate>
    <ItemTemplate>
        <tr>
            <td class="style2">
            <asp:DropDownList  ID="DropDownList1"
                DataTextField="ID" runat="server"
                DataValueField="Desc" 
SetValue='<%# Eval("Code") %>' datasourceid="dsCategory" 
datatextfield="ID" datavaluefield="desc" DataMember = "Source" onprerender="DropDownDataBinding">
            </asp:DropDownList>
<asp:ObjectDataSource ID="dsCategory" runat="server" SelectMethod="PhysicianSource" TypeName="WebApplication.WebForm1" />
            </td>

            </td>
        </tr>

代碼背后

protected void DropDownDataBinding(object sender, EventArgs e) //Method to set the selected value on Category dropdown inside repeater
{
    DropDownList sel = (DropDownList)sender;
    sel.Value = sel.Attributes["SetValue"];
    ListItem li = new ListItem("<< Select >>", "");
    sel.Items.Insert(0,li);
}

protected DataSet PhysicianSource()
{
        DataSet ds = new DataSet();
DataTable dt = ds.Tables.Add("Source");
dt.Columns.Add("ID", Type.GetType("System.String"));
dt.Columns.Add("Desc", Type.GetType("System.String"));

Provider oProvider = new Provider();
List<ProviderLabel> lstprovider = oProvider.RetrievePhysicianList();
foreach (ProviderLabel item in lstprovider)
{
    DataRow dr = dt.NewRow();
    dr[0] = item.ProviderCode.ID.ToString();
    dr[1] = item.Name.ToString();
    dt.Rows.Add(dr);
}
return ds;
}

Answer 3

1. 嘗試在數據綁定后設置所選值
2. 不要在每次回發時都設置列表內容。 檢查Page.IsPostBack（）。 請注意，這僅在啟用ViewState的情況下有效。

Answer 4

//Declare Class Scoped DataSet and DataTable variables
DataSet ds;
DataTable dt;

//Bind repeater and DataSource method
private void PhysicianSource()
{
    ds = new DataSet();
    dt = ds.Tables.Add("Source");
    dt.Columns.Add("ID", Type.GetType("System.String"));
    dt.Columns.Add("Desc", Type.GetType("System.String"));

    Provider oProvider = new Provider();
    List<ProviderLabel> lstprovider = oProvider.RetrievePhysicianList();
    foreach (ProviderLabel item in lstprovider)
    {
        DataRow dr = dt.NewRow();
        dr[0] = item.ProviderCode.ID.ToString();
        dr[1] = item.Name.ToString();
        dt.Rows.Add(dr);
    }

    drpPhysicianCode.DataSource = ds;
    drpPhysicianCode.DataMember = "Source";
    drpPhysicianCode.DataTextField = "ID";
    drpPhysicianCode.DataValueField = "ID";
    drpPhysicianCode.DataBind();
}

//Repeater Item Data Bound event in which we would find Controls to be bound
//and set DataSource and SelectedValue
protected void rptrPatientList_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DropDownList DropDownList1 = e.Item.FindControl("DropDownList1") as DropDownList;
        if (DropDownList1 != null)
        {
           DropDownList1.DataSource = dt;
           DropDownList1.DataBind();

           DropDownList1.SelectedValue = // DataBinder Eval 'Code' //;
        }
    }
}


<asp:Repeater ID="rptrPatientList" runat="server" OnItemDataBound="rptrPatientList_ItemDataBound">
    <HeaderTemplate></HeaderTemplate>
    <ItemTemplate>
        <tr>
            <td class="style2">
            <asp:DropDownList  ID="DropDownList1"
                DataTextField="ID" runat="server"
                DataValueField="Desc"
                SelectedValue='<%# Eval("Code") %>'
                DataSource="ds">
            </asp:DropDownList>
            </td>

            </td>
        </tr>