Problem related to dropdownlist

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Dear sir,
I have 3 dropdown lists. 1st contains the continental. 2nd contains country. 3rd contains city.
i want to choose first a continent. when i choose continent i need country in in country dropdown. and when i choose a country a respected city will came in city dropdown list.
i have done all of these correctly. but my problem is when i am selecting a continent my page goes to refresh and it's taking a long time.
please provide me some help with the a little example.
sir please provide solution with ajax dropdown also.

thanking you.
Manoj joshi

Posted 2-Jun-12 22:28pm

manu027

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OriginalGriff 3-Jun-12 4:36am

And what have you tried so far?

manu027 3-Jun-12 4:50am

sir i have used selectedindexchanged event for selecting a country, and then i am getting cities of that selected country. but i dont know how to stop page refresh

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Prasad_Kulkarni · Answer 1 · 2012-06-02T23:07:00

Please refer:
Simple Way to Implement Country/State/City Dropdown List in ASP.NET (VB)[^]
Ajax Cascading Dropdownlist Sample with database using asp.net[^]
CascadingDropDown Demonstration[^]
Cascading DropDownList[^]
Using CascadingDropDown with a Database[^]

Note: Use update panel control to stop page refersh.

Dipankar Basu · Answer 2 · 2012-06-02T23:40:00

Use SelectedIndexChanged event to do this.

Set autopostback true for continent and country dropdown

Suppose there are three method ShowContinent(), ShowCountry() and ShowCity()

Use ShowContinent() on pageload, ShowCountry() on Continent dropdown's SelectedIndexChanged event and ShowCity() on Country dropdown's SelectedIndexChanged event

For stop page refresh use ajax, put all three dropdown inside ContentTemplate tag

C#

<updatepanel id="UpdatePanel1" runat="server">
<contenttemplate>

</contenttemplate>
</updatepanel>

taha bahraminezhad Jooneghani · Answer 3 · 2012-06-03T01:19:00

first optimize your database!
use relational database!

second use update panel like below code snippet:

XML

<asp:DropDownList ID="continental" runat="server" OnSelectedIndexChanged="taha"></asp:DropDownList>

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:DropDownList ID="country" runat="server"></asp:DropDownList>
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger  ControlID="continental"                 EventName="taha"/>
            </Triggers>
        </asp:UpdatePanel>

just put the content that update in call back in ContentTemplate.
and set the controlID of your trigger to ID of control that causes the postback event!

Linto Leo Tom · Answer 4 · 2012-06-03T09:05:00

Solution 4

Hi,

You can use refreshpanels. On the selected index change of first dropdown refresh only the second dropdown. On the selected index change of second dropdown refresh only the third dropdown,

Happy Coding :)

Posted 3-Jun-12 9:05am

Linto Leo Tom

Problem related to dropdownlist

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