how can i avoid writing code on every dropdown selectedindexchanged

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C#

SqlDataAdapter da4 = new SqlDataAdapter("select * from vehicle_category where vehicle_name='" + ddlvnameri.SelectedItem.ToString() + "' ", con);
DataTable dt4 = new DataTable();
da4.Fill(dt4);
if (ddlvtype.SelectedItem.ToString() == "AC" && ddlrate.SelectedItem.ToString() == "Rate/km")
{
    txtrate.Text = dt4.Rows[0]["ac_rate_km"].ToString();
}
else if (ddlvtype.SelectedItem.ToString() == "Non-AC" && ddlrate.SelectedItem.ToString() == "Rate/km")
{
    txtrate.Text = dt4.Rows[0]["rate_km"].ToString();
}
else if (ddlvtype.SelectedItem.ToString() == "AC" && ddlrate.SelectedItem.ToString() == "Rate/day")
{
    txtrate.Text = dt4.Rows[0]["ac_rate_day"].ToString();
}
else
{
    txtrate.Text = dt4.Rows[0]["rate_day"].ToString();
}

this code i have to write on every ddl_selectedindexchanged and i have to use this bunch of dropdown list 10 times how can i reduce dis

[edit]Code block added - OriginalGriff[/edit]

Posted 15-Mar-13 21:52pm

Member 9671810

Updated 15-Mar-13 22:01pm

OriginalGriff

v2

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OriginalGriff · Answer 1 · 2013-03-15T22:05:00

Solution 1

I assume you mean that you have 10 drop down lists and you need code which differs only in which control they use as the source for the SQL statement? If so, then it is pretty easy: just send all teh drop down lists to the same vent handler and use the sender parameter to determine which control it is:

C#

DropDownList ddl = sender as DropDownList;
if (ddl != null)
   {
   SqlDataAdapter da4 = new SqlDataAdapter("select * from vehicle_category where vehicle_name='" + ddl.SelectedItem.ToString() + "' ", con);
   ...

If that isn't your problem, then you need to explain in more detail what you are having problems with.

Posted 15-Mar-13 22:05pm

OriginalGriff

Comments

Member 9671810 16-Mar-13 4:28am

i mean i have to write dis code on ddlrate,ddlvtype,ddlvnameri selected index changed.
and i have ddlrate1,ddlvtype1,dd1vname1....ddlrate10,ddlvtype10,dd1vname10.. so do i have to write dis code onevery ddlselected index changed..

and where should i write the above code..which you gave..

OriginalGriff 16-Mar-13 4:47am

When you enter an Event handler you are given a "object sender" and an "EventArgs e" parameter, which give you information about what caused the event. The "sender" parameter is the control that started it. So if you have the same event handler method called from two different DropDownList controls, the "sender" parameter contains the specific drop down list that changed it's selected item. The above code casts the "sneder" to a drop down so you can use it directly as a DropDownList.
The code would go at the top of your event handler, to cast the control for you, and screen out any "false" events which manage to get into the method. You c an then use the same handler for all you drop downs, using "ddl" instead of each control name .

Does that make any sense? It's difficult to tell without being able to see when your eyes glaze over...:laugh:

Member 9671810 16-Mar-13 5:36am

<tr>
<td>
<asp:Label ID="lblvnameri1" runat="server" Text="VEHICLE NAME">
</td>
<td>
<asp:DropDownList ID="ddlvnameri1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlvnameri1_SelectedIndexChanged">

<asp:DropDownList ID="ddlvtype1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlvtype1_SelectedIndexChanged">
<asp:ListItem>AC
<asp:ListItem>Non-AC

</td>
<td>
<asp:DropDownList ID="ddlrate1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlrate1_SelectedIndexChanged">
<asp:ListItem>Rate/km
<asp:ListItem>Rate/day

</td>
<td>
<asp:TextBox ID="txtrate1" runat="server">
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblvnameri2" runat="server" Text="VEHICLE NAME">
</td>
<td>
<asp:DropDownList ID="ddlvnameri2" runat="server" AutoPostBack="True">

<asp:DropDownList ID="ddlvtype2" runat="server" AutoPostBack="True">
<asp:ListItem>AC
<asp:ListItem>Non-AC

</td>
<td>
<asp:DropDownList ID="ddlrate2" runat="server" AutoPostBack="True">
<asp:ListItem>Rate/km
<asp:ListItem>Rate/day

</td>
<td>
<asp:TextBox ID="txtrate2" runat="server">
</td>
</tr>

dis is my source code.. i have written <tr> block twice similarly i have to write 10 times and in each <tr> there are many dropdownlists.. and i have to write that code in each ddlselected index changed. which is not feasible.

Prasad Khandekar · Answer 2 · 2013-03-15T22:22:00

Solution 2

Hello,

You can turn your code in a function with following signature and attach it every dropdownlist control in your page via OnSelectedIndexChanged. The parameter sender should help you in determining which control has raised the event.

C#

void ddlSelectedIndexChanged(object sender, System.EventArgs e)

Regards,

Posted 15-Mar-13 22:22pm

Prasad Khandekar

Comments

Member 9671810 16-Mar-13 4:29am

i have to write dis code on ddlrate,ddlvtype,ddlvnameri selected index changed. and i have ddlrate1,ddlvtype1,dd1vname1....ddlrate10,ddlvtype10,dd1vname10.. so do i have to write dis code onevery ddlselected index changed..

Prasad Khandekar 16-Mar-13 9:23am

Hello,

No you write this code only once. And for every dropdown list specify it via OnSelectedIndexChanged.

Regards,