使用回发的页面加载时数据未加载

Question

我遇到了问题。页面加载后数据不会加载。我必须在下拉列表中选择一个项目才能加载。甚至在我选择下拉列表中的任何项目之前，我都需要加载它。

这是我的代码。

 protected void ddlPeriodStamp_SelectedIndexChanged(object sender, System.EventArgs e)
{
    string selectedGroup = string.Empty;
    DropDownList ddlItemGroup = (DropDownList)sender;

    if (ddlItemGroup.SelectedValue != null)

        TreatmentGroup = ddlItemGroup.SelectedValue;
        ApplyGridFilter(ddlItemGroup.SelectedValue);


}

protected void ApplyGridFilter(string TreatmentGroup)
{
    string selectedGroup = string.Empty;
    DBDataSource1.State.BusinessObject.DataPump.FormFilters.Clear();
    DBDataSource1.State.BusinessObject.DataPump.FormFilters.Add("TreatmentGroup", TreatmentGroup);
    DBDataSource1.State.BusinessObject.Fill(null);
    MedicalSchemeDetailGrid.DataBind();
}
protected void Page_LoadComplete(object sender, System.EventArgs e)
{

    if (!this.IsPostBack)
            ApplyGridFilter(string.Empty);
}

Answer 1

当ispostBack 为假时调用ApplyGridFilter(string.Empty);，当ispostBack 为真时调用ApplyGridFilter(ddlItemGroup.SelectedValue);

protected void Page_LoadComplete(object sender, System.EventArgs e)
 {

   if (this.IsPostBack)
   {
     ApplyGridFilter(ddlItemGroup.SelectedValue);// it will hit on first time page load 
   }
   else
   {
     ApplyGridFilter(string.Empty);// it will hit while you change the dropdown items, But you should set true for **IsAutoPostBack** property on dropsownlist.    
   }
 }

Answer 2

您需要在 Page_Load 事件中填写数据，而不是在 Page_LoadComplete 事件中。根据 MSDN：

LoadComplete 事件发生在所有回发数据和视图状态之后 数据被加载到页面中并且在 OnLoad 方法之后 调用页面上的所有控件。

protected void Page_Load(object sender, System.EventArgs e)
{
    if (!this.IsPostBack)
        ApplyGridFilter(string.Empty);
}