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Thread: [RESOLVED] Persistent data in a Chart and Adding points from front end

  1. #1

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    Resolved [RESOLVED] Persistent data in a Chart and Adding points from front end

    I am building an ASP.net application using VB. that uses a chart. I want to add data from the front end and keep that data that is already in the chart. From my research it appears I need the ChartSerializer, but I can not find any code example.

    To try to get this to work, I just added a Chart and a button to WebForm1.aspx
    Code:
        <asp:Chart ID="Chart1" runat="server">
            <Series>
                <asp:Series Name="Series1">
                </asp:Series>
            </Series>
            <ChartAreas>
                <asp:ChartArea Name="ChartArea1">
                </asp:ChartArea>
            </ChartAreas>
        </asp:Chart>
        <asp:Button ID="Button3" runat="server" Text="Button" />
    In WebForm1.aspx.vb I have coe for a button that adds three records to the graph

    Code:
        Protected Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
            Chart1.Series(0).Points.Add(125)
            Chart1.Series(0).Points.Add(300)
            Chart1.Series(0).Points.Add(400)
        End Sub
    What I want is that every time I click Button3, I want to add three more bars on the graph. What happens now is the chart appears to be recreated, and no matter how many times I hit the button, I only have 3 bars.

    What I have tried is to define a public variable to hold the data, add the data to this variable, and then set the Chart.Series(0) equal to that variable. For example

    Declare a public class variable in WebForm1.aspx.vb
    Code:
    public s0 as New Series
    Then in WebForm1.aspx.vb
    Code:
       Protected Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
            ss0.Points.Add(250)
            Chart1.Series(0) = ss0
    end sub
    The data is not persistent. I end up having only one column in my chart.

    Any Idea as to how I can get the data to be persistent?

  2. #2
    King of sapila
    Join Date
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    Re: Persistent data in a Chart and Adding points from front end

    Hi.
    Yes asp.net does not maintain values as the pages are stateless.
    However you can keep an value in a cookie or in a session or in server memory on in viewstate (worst scenario).
    However some controls may do that for you.
    Thy reading and then try using "If not page.ispostaback" and the opposite and compare the values
    ἄνδρα μοι ἔννεπε, μοῦσα, πολύτροπον, ὃς μάλα πολλὰ
    πλάγχθη, ἐπεὶ Τροίης ἱερὸν πτολίεθρον ἔπερσεν·

  3. #3

    Thread Starter
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    Re: Persistent data in a Chart and Adding points from front end

    Thank you for your reply. Other objects were persistent, and the inconsistency with the chart was frustrating.

    What I ended up doing is storing all the data into a public list, then then every time I loaded the chart looped through the list and added the data points to the chart. This appears to be working fine for what I want it to do.

  4. #4
    King of sapila
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    Re: [RESOLVED] Persistent data in a Chart and Adding points from front end

    NP.
    If there is a javascript made chart then I would rather go with that since asp.net controls are giving hell to the page behind.
    If you look at the page source you can see the pages bloating with gibberish data, that is probably the viewstate holding your controls data.
    A clean javascript could reduce that dramatically and speed up the pages. But, it's a whole new world .
    ἄνδρα μοι ἔννεπε, μοῦσα, πολύτροπον, ὃς μάλα πολλὰ
    πλάγχθη, ἐπεὶ Τροίης ἱερὸν πτολίεθρον ἔπερσεν·

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