How to work with two update panels on same .aspx page

Question

I have two update panels on a page. And I want to update both of them conditions at different-2 conditions. But I don't know why this is not happening. I have specified triggers for both but not helpful, below is my code.

Please let me know Where I am wrong.

Actually there are three dropdown lists in first update panel when their selectedindexchange is fired then the second update panel's content also updates.

<asp:UpdatePanel ID="upSearch" runat="server" ChildrenAsTriggers="true" UpdateMode="Conditional">
    <ContentTemplate>
        <div style="float: left; width: auto;">

            <asp:DropDownList ID="ddlLocation" runat="server" Width="206px" DataTextField="LocationName"
                DataValueField="Locationid" AutoPostBack="true" OnSelectedIndexChanged="ddlLocation_SelectedIndexChanged">
            </asp:DropDownList>

            &nbsp;
            <asp:DropDownList ID="ddlArea" runat="server" Width="200px" DataTextField="AreaName"
                DataValueField="Areaid" AutoPostBack="true" OnSelectedIndexChanged="ddlArea_SelectedIndexChanged">
            </asp:DropDownList>

            &nbsp;
            <asp:DropDownList ID="ddlRoom" runat="server" Width="200px" DataTextField="RoomName"
                DataValueField="Roomid">
            </asp:DropDownList>
            &nbsp;

        </div>
        <div style="float: left; width: 80px;">
            <asp:Button ID="btnSearch" runat="server" Text="Search" ValidationGroup="vgSearch"
                CssClass="bluebtn" UseSubmitBehavior="false" OnClick="btnSearch_Click" />
        </div>
        <div style="float: left; width: 99%; padding: 5px 0px;">
        </div>
    </ContentTemplate>
  </asp:UpdatePanel>

And the second one is as follow:-

<asp:UpdatePanel ID="UpdatePanel1" runat="server" ChildrenAsTriggers="true" UpdateMode="Conditional">
<ContentTemplate>
    <asp:Calendar ID="calSchedule" runat="server" NextPrevFormat="FullMonth" OnDayRender="calSchedule_DayRender"
        OnVisibleMonthChanged="calSchedule_VisibleMonthChanged">
        <DayHeaderStyle CssClass="dayheaderStyle" />
        <NextPrevStyle />
        <OtherMonthDayStyle BackColor="#ffffff" />
        <SelectedDayStyle />
        <TitleStyle CssClass="titleStyle" />
        <TodayDayStyle BackColor="#ffffa0" ForeColor="#6699cc" />
        <WeekendDayStyle />
        <DayStyle CssClass="dayStyle" />
    </asp:Calendar>
</ContentTemplate>
<Triggers>
    <asp:AsyncPostBackTrigger ControlID="btnSearch" EventName="Click" />
</Triggers>
</asp:UpdatePanel>

Answer 1

First of all I would like to recall the use of UpdateMode

• Always The panel will update its content on every post on the page, they can be partial rendering posts or full posts, in both cases the content of the panel will be updated

• Conditional The content of the panel will only be updated when different conditions are met:

  • By default the events triggered by its child objects will trigger an update, you can change this behavior setting ChildrenAsTriggers="false"

  • When you declare a trigger in the Triggers section of the UpdatePanel

  • When you explicitly call the UpdatePanel.Update() method

  • Full page posts will trigger the update

The following code does the following:

• Each UpdatePanel is updated when its child controls raise an event

• The UpdatePanel 1 named: up1 will be updated only when its child controls raise an event

• The UpdatePanel 2 named up2 will be updated when its child controls raise an event

• The UpdatePanel 2 named up2 will also be updated when the triggers defined are fired, in this case, when the DropDownList named ddl1OnPanel1 on the UpdatePanel 1 fires its SelectedIndexChanged

• The UpdatePanel 2 named up2 will also be updated when the DropDownList named ddl2OnPanel1 on the UpdatePanel 1 raises its SelectedIndexChanged, because in code it explicitly calls: this.up2.Update();

I think that tweaking this code, you could achieve your desired goal, just copy paste it on a new page and run it

Check the following code (see how the labels showing the date are affected in different ways depending on the events raised):

Code Behind

    protected void ddl1OnPanel1_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.lblMessageOnPanel1.Text = "From ddl1 " + DateTime.Now.ToString();
        this.calendarOnPanel2.SelectedDate = DateTime.Today.AddDays(1);
        this.lblMessageOnPanel2.Text = "From ddl1 " + DateTime.Now.ToString();
    }

    protected void ddl2OnPanel1_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.lblMessageOnPanel1.Text = "From ddl2 " + DateTime.Now.ToString();
        this.calendarOnPanel2.SelectedDate = DateTime.Today.AddDays(2);
        this.lblMessageOnPanel2.Text = "From ddl2 " + DateTime.Now.ToString();
        this.up2.Update();
    }

ASPX

    <asp:ScriptManager runat="server" ID="scriptManager" />
    <asp:Button Text="Full Post" runat="server" />
    <br />
    <asp:UpdatePanel runat="server" ID="up1" UpdateMode="Conditional">
        <ContentTemplate>
            <asp:DropDownList runat="server" ID="ddl1OnPanel1" AutoPostBack="true" OnSelectedIndexChanged="ddl1OnPanel1_SelectedIndexChanged">
                <asp:ListItem Text="text1" />
                <asp:ListItem Text="text2" />
            </asp:DropDownList>
            <br />
            <asp:DropDownList runat="server" ID="ddl2OnPanel1" AutoPostBack="true" OnSelectedIndexChanged="ddl2OnPanel1_SelectedIndexChanged">
                <asp:ListItem Text="text3" />
                <asp:ListItem Text="text4" />
            </asp:DropDownList>
            <br />
            <asp:Label runat="server" ID="lblMessageOnPanel1" />
            <br />
            <asp:Button ID="Button1" Text="text" runat="server" />
            <br />
            On every post on Panel 1: <%:DateTime.Now %>
        </ContentTemplate>
    </asp:UpdatePanel>

    <br />
    <br />
    <asp:UpdatePanel runat="server" ID="up2" UpdateMode="Conditional">
        <ContentTemplate>
            <asp:Calendar ID="calendarOnPanel2" runat="server" >
                <DayHeaderStyle CssClass="dayheaderStyle" />
                <NextPrevStyle />
                <OtherMonthDayStyle BackColor="#ffffff" />
                <SelectedDayStyle />
                <TitleStyle CssClass="titleStyle" />
                <TodayDayStyle BackColor="#ffffa0" ForeColor="#6699cc" />
                <WeekendDayStyle />
                <DayStyle CssClass="dayStyle" />
            </asp:Calendar>
            <br />
            <asp:Label ID="lblMessageOnPanel2" runat="server" />
            <br />
            On every post On Panel 2: <%:DateTime.Now %>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="ddl1OnPanel1" EventName="SelectedIndexChanged" />
        </Triggers>
    </asp:UpdatePanel>

Simple Output

You could change the UpdateMode="Always" on the UpdatePanel 2, to see the difference, if you do it, this panel will be updated on every post, either full posts or posts coming from the UpdatePanel1