Selectedindexchanged不会触发

Question

我有一个在页面加载时填充的下拉列表，默认情况下，所选索引为0，并将其设置为一个emty字符串。在页面加载时，如果我们更改所选值，则所选索引方法不会触发。

 if(!page.isPostback)
    {
      this.ddl.DataSource = list;
      this.ddl.DataValueField = "Id";
      this.ddl.DataTextField = "Name";
      this.ddl.DataBind();
      this.ddl.Items.Insert(0, String.Empty);

      if (Request.QueryString != null)
      {
           string name = Request.QueryString["name"];
           long Id = list.Where(item => item.Name == name).Select(item =>item.Id).SingleOrDefault();
           this.selectedIndex = 1;
           this.ddl.SelectedValue = Id.ToString();
      }

    }

Answer 1

应该如此。如果要从事件和/或页面加载执行某些逻辑，请将该逻辑放在单独的方法中，以便您可以从页面加载中轻松调用它。

Answer 2

 private void BindList()
        {
                this.ddl.Items.Clear();
                this.ddl.DataSource = list;
                this.ddl.DataValueField = "Id";
                this.ddl.DataTextField = "Name";
                this.ddl.DataBind();
                this.ddl.Items.Insert(0, String.Empty);
                this.ddl.Items.SelectedIndex = 0;
        }

---

if(!page.isPostback)
    {

      BindList();
      if (Request.QueryString != null)
      {
           string name = Request.QueryString["name"];
           long Id = list.Where(item => item.Name == name).Select(item =>item.Id).SingleOrDefault();
           this.ddl.Items.ClearSelection();
           this.ddl.Items.FindByValue(Id.ToString()).Selected = true;
      }

    }