Dropdownlist based on dropdownlist C# Asp.Net

Question

I have 3 dropdownlists and I already set dropdownlist 2 based on SelectedValue of dropdownlist 1, but my dropdownlist 3 has no response based on selection in dropdownlist2

if(DropDownList1.SelectedValue =="1")
{
    DropDownList2.Items.Clear();
    DropDownList2.Items.Insert(0, new ListItem("A", ""));
    DropDownList2.Items.Insert(1, new ListItem("B", ""));
}

This is how I add items in Dropdownlist2 based on selection in Dropdownlist1 but it does not work in the third dropdownlist whic does not have any item after I select A in Dropdownlist2:

if (DropDownList2.SelectedValue == "0")
{
    DropDownList3.Items.Clear();
    DropDownList3.Items.Insert(0, new ListItem("A-1", ""));
}

are you able to debug the code? Does is execute the code of populating DropDownList3 ? When these two codes are executed? — Chetan
– Chetan, Commented Oct 7, 2019 at 3:20
it should be selectedIndex not selectedvalue right? added an answer and explanation — Gabriel Llorico
– Gabriel Llorico, Commented Oct 7, 2019 at 3:27
@ChetanRanpariya the only problem here is the dropdownlist 3 does not have any item after i selected something in dropdownlist 2 — Hollow Looi
– Hollow Looi, Commented Oct 7, 2019 at 3:30
If you debug the code, you can figure out why it is not adding any items in DropDownList3. @HollowLooi — Chetan
– Chetan, Commented Oct 7, 2019 at 3:34

Gabriel Llorico · Accepted Answer · 2019-10-07 03:42:07Z

1

i think you got the selectedvalue wrong, i think it should be selectedindex

if (DropDownList2.SelectedIndex == 0)
{
    DropDownList3.Items.Clear();
    DropDownList3.Items.Insert(0, new ListItem("A-1", ""));
}

if you will still want to use selectedvalue change the bindings of new ListItem("A", "") to new ListItem("A", "");

//populate first ddl with corret item and value
if(DropDownList1.SelectedValue =="1")
{
            DropDownList2.Items.Clear();
            DropDownList2.Items.Insert(0, new ListItem("A", ""));
            DropDownList2.Items.Insert(1, new ListItem("B", ""));
}

if (DropDownList2.SelectedValue == "A")
{
    DropDownList3.Items.Clear();
    DropDownList3.Items.Insert(0, new ListItem("A-1", ""));
}

DropdownList.Items.Insert implements ddl.Items.Insert(indexPosition, new ListItem("displayItem", "value");

so since you are searching for "0" in the selectedvalue which in your example does not exists since new ListItem("A", "") it will not execute the statement inside

edited Oct 7, 2019 at 3:42

answered Oct 7, 2019 at 3:22

Gabriel Llorico

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3 Comments

Hollow Looi Over a year ago

I changed into index, but the third dropdownlist still show blank for me

Gabriel Llorico Over a year ago

@HollowLooi can you show your code for the implementation of the dropdownlist?

Hollow Looi Over a year ago

Do you mean the whole function or ?

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