How to clear exisiting dropdownlist items when its content changes

Question

ddl2 populates based on ddl1 selected value successfully   My issue is the data that is already present in ddl2 does not clear before appending the new data so ddl2 content just continues to grow every time ddl1 is changed     lt asp DropDownList ID  ddl1  RunAt  Server  DataSourceID  sql1  DataValueField  ID1  DataTextField  Name2  AppendDataBoundItems  True  AutoPostBack  True  gt     lt asp ListItem Text  ALL  Selected  True  Value  0   gt   lt  asp DropDownList gt    lt asp DropDownList ID  ddl2  RunAt  Server  DataSourceID  sql2  DataValueField  ID2  DataTextField  Name2  AppendDataBoundItems  True  AutoPostBack  True  gt     lt asp ListItem Text  ALL  Selected  True  Value  0   gt   lt  asp DropDownList gt    lt asp SqlDataSource ID  sql1  RunAt  Server  SelectCommand  sp1  SelectCommandType  StoredProcedure   gt    lt asp SqlDataSource ID  sql2  RunAt  Server  SelectCommand  sp2  SelectCommandType  StoredProcedure  gt     lt SelectParameters gt       lt asp ControlParameter Type  Int32  Name  ID1  ControlID  ddl1  PropertyName  SelectedValue   gt     lt  SelectParameters gt   lt  asp SqlDataSource gt    I have tried re-databinding in code behind on selected index change and also items clear with little success   Protected Sub ddl1 SelectedIndexChanged ByVal sender As Object  ByVal e As EventArgs      ddl2 Items Clear       ddl2 DataSource   sql2     ddl2 DataBind   End Sub   QUESTION  How to get items present in an asp dropdownlist to clear before new values are populated when the dropdownlists content is dependent on another dropdownlists selected value   Please post any code in VB

User · Answer

just compiled your code and the only thing that is missing from it is that you have to Bind your ddl2 to an empty datasource before binding it again like this:

Protected Sub ddl1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) //ddl2.Items.Clear()
ddl2.DataSource=New List(Of String)()
ddl2.DataSource = sql2
ddl2.DataBind() End Sub

and it worked just fine

User · Answer

Using ddl Items Clear   will clear the dropdownlist however you must be sure that your dropdownlist is not set to    AppendDataBoundItems  True    This option will cause the rebound data to be appended to the existing list which will NOT be cleared prior to binding   SOLUTION  Add AppendDataBoundItems  False  to your dropdownlist   Now when data is rebound it will automatically clear all existing data beforehand   Protected Sub ddl1 SelectedIndexChanged sender As Object  e As EventArgs      ddl2 DataSource   sql2     ddl2 DataBind   End Sub   NOTE  This may not be suitable in all situations as appenddatbound items can cause your dropdown to append its own data on each change of the list     TOP TIP  Still want a default list item adding to your dropdown but need to rebind data   Use AppendDataBoundItems  False  to prevent duplication data on postback and then directly after binding your dropdownlist insert a new default list item   ddl Items Insert 0  New ListItem  Select

User · Answer

Just 2 simple steps to solve your issue  First of all check AppendDataBoundItems property and make it assign false  Secondly clear all the items using property  clear      ddl1 Items Clear    ddl1 datasource   sql1  ddl1 DataBind

User · Answer

Please use the following  ddlCity Items Clear

User · Answer

You should clear out your listbbox prior to binding    Me ddl2 Items Clear       now set datasource and bind

[asp.net] How to clear exisiting dropdownlist items when its content changes?

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