在ASP.NET中刷新页面后如何将用户添加的项目带入下拉列表？

Question

I have a dropdownlist in my aspx page: ddlProgramList , which is loaded in page_load() event from Sql Server via the query: Select Name from Programs; The default value of this DDL is: Select Program

In the same page, I have a button in aspx like below, where a user can add a new Program if it does not exist in the current dropdownlist options:

<asp:TextBox ID="txtPrgLabel" runat="server" style="width:295px"></asp:TextBox>
<asp:Button ID="btnSaveProgram" runat="server" Text ="Save Program" OnClick="btnSaveProgram_Click" />

btnSaveProgram_Click function basically does an insertion to the related SQL table with the content of txtPrgLabel . After insertion completes, Response.Redirect(Request.RawUrl); is used to refresh the page and update the content of the DDL. This process works successfully.

What I want is: After a user adds a program, when page is refreshed, the DDL should automatically bring the recently added program instead of the default "Select Program" content. I could not find a way to manage this. Any help or advice would be appreciated.

Answer 1

Here are the steps to manage this demand:

1- I've defined a global variable:

public int maxProgramID = 0;

2- Found MaxID in page_load:

string maxID = programsDataTable.AsEnumerable()
.Max(row => row["ProgramId"])
.ToString();

3- Added it to my session in btnSaveProgram_Click:

Session["AddedProgram"] = new DDLProgram { Name = programName, Value = maxProgramID + 1 };

4- Select the value automatically in page_load:

if(Session["AddedProgram"] != null) ddl.SelectedValue = Session["AddedProgram"];

Thanks @penleychan to help me out by commenting under my question.