Dynamic Dropdownlist in .NET

Question

Hi I know dynamic dropdownlist in PHP but I want to know how to create dynamic dropdownlist in .NET ? Please tell me anyone with an example ? Thanks

Jignesh Trivedi · Answer

hi vinit please refer http://www.c-sharpcorner.com/uploadfile/dhananjaycoder/dynamically-adding-dropdown-using-jquery/ http://stackoverflow.com/questions/5458231/dynamically-add-drop-down-lists-to-html-form this will help you to create drop down client side. hope this help.

Satyapriya Nayak · Answer

Hi Vineet 1. Create dropdownlist dynamically with autopostback property true 2. Keep dropdownlist during postback 3. Maintain selected value during postback. Here is the sample for this. In aspx page: To Create Dynamic Dropdownlist: protected void Page_Load(object sender EventArgs e) { if (!Page.IsPostBack) { CreateDynamicTable(); } } private void CreateDynamicTable() { // Fetch the number of Rows and Columns for the table // using the properties int tblRows = 3; int tblCols = 3; // Now iterate through the table and add your controls for (int i = 0; i { TableRow tr = new TableRow(); for (int j = 0; j { TableCell tc = new TableCell(); DropDownList ddl = new DropDownList(); ddl.ID = ddl- + i.ToString() + - + j.ToString(); for (int k = 0; k { ddl.Items.Add(new ListItem(item-+k.ToString()k.ToString())); } ddl.AutoPostBack = true; ddl.SelectedIndexChanged += new EventHandler(ddl_SelectedIndexChanged); // Add the control to the TableCell tc.Controls.Add(ddl); // Add the TableCell to the TableRow tr.Cells.Add(tc); } // Add the TableRow to the Table tbl.Rows.Add(tr); tbl.EnableViewState = true; ViewState[tbl] = true; } } protected void ddl_SelectedIndexChanged(object sender EventArgs e) { // what you want to perform } To retrieve value on button click: protected void btnSet_Click(object sender EventArgs e) { foreach (TableRow tr in tbl.Controls ) { foreach (TableCell tc in tr.Controls) { if (tc.Controls[0] is DropDownList) { Response.Write(((DropDownList)tc.Controls[0]).SelectedItem.Text+ ); } } Response.Write( ); } } Right Now No output because dynamic controls are lost in postback then what to do. So we need to save dynamic controls value and generate dynamic controls again.we need to maintain viewstate. protected override object SaveViewState() { object[] newViewState = new object[2]; List txtValues = new List (); foreach (TableRow row in tbl.Controls) { foreach (TableCell cell in row.Controls) { if (cell.Controls[0] is DropDownList) { txtValues.Add(((DropDownList)cell.Controls[0]).SelectedIndex.ToString()); } } } newViewState[0] = txtValues.ToArray(); newViewState[1] = base.SaveViewState(); return newViewState; } protected override void LoadViewState(object savedState) { //if we can identify the custom view state as defined in the override for SaveViewState if (savedState is object[] && ((object[])savedState).Length == 2 && ((object[])savedState)[0] is string[]) { object[] newViewState = (object[])savedState; string[] txtValues = (string[])(newViewState[0]); if (txtValues.Length > 0) { //re-load tables CreateDynamicTable(); int i = 0; foreach (TableRow row in tbl.Controls) { foreach (TableCell cell in row.Controls) { if (cell.Controls[0] is DropDownList && i { ((DropDownList)cell.Controls[0]).SelectedIndex = Convert.ToInt32(txtValues[i++]); } } } } //load the ViewState normally base.LoadViewState(newViewState[1]); } else { base.LoadViewState(savedState); } } Please refer the below link http://techbrij.com/200/create-dynamic-dropdownlists-in-asp-net http://www.aspsnippets.com/Articles/Creating-Dynamic-DropDownList-Controls-in-ASP.Net.aspx Thanks