Chart Graphics Refresh

[Michelle]

I have a chart that is bound to a datasource.  When data is updated in the table, the chart is not refreshed or updated.  I have tried:
.update()
.updategraphics()
.refresh()

And also:
.datasource= mybindingsource
.databind()

The latter causes a large red X to be displayed instead of a chart.

Any help?

[Dwight]

Hello Michelle,

Just calling the DataBind() method should suffice. Here is the code I used to test the chart:

public partial class Form1 : Form
{
    private DataTable table;

    public Form1()
    {
        InitializeComponent();

        table = InitTable();
        this.radChart1.DataSource = table;
        this.radChart1.DataBind();
    }

    private static DataTable InitTable()
    {
        DataTable table = new DataTable();
        Random r = new Random(table.GetHashCode());
        table.Columns.Add("First", typeof(int));
        table.Columns.Add("Second", typeof(int));

        for (int i = 0; i < 10; i++)
        {
            DataRow row = table.NewRow();
            row["First"] = r.Next(10, 100);
            row["Second"] = r.Next(110, 200);

            table.Rows.Add(row);
        }

        return table;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int value = (int)this.table.Rows[0][0];
        value += 100;
        this.table.Rows[0][0] = value;

        this.radChart1.DataBind();
    }
}

The designer only contains a chart and a button.

If you have a more complicated scenario in which calling the DataBind does not work, please, open a support ticket and attach a sample project. Note, that attachments in the forum threads are not allowed.

Sincerely yours,
Evtim
the Telerik team

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[Michelle]

Thank you for your response.  My situation was more complicated.  Unfortunately, my period of support has ended which is why I have posted this on the community forums instead of opening a support ticket.  Fortunately, I have resolved the issue myself :)

For a little more background information, I will explain a bit more of what was happening and share the workaround/solution I have identified.

Background Information:  I have a form with a Chart (RadChart1) bound to a table (ChartDimensions).  I also have a listbox (LstShape) on the side of the form.  The table ChartDimensions includes the X and Y locations required to draw a Line Chart to give the desired shape.  Upon selection of an item from the LstShape, ChartDimensions has a query applied to return only the X and Y coordinates relative to the requested shape.  The initial shape would load in the chart fine, but subsequent selections made no update to the chart.  Initially, I applied only the methods I posted earlier, but could not identify why I was getting the giant red X in place of my chart.  I thought it was possible that the RadChart1 was having difficulty finding cohesiveness in the data, thus giving me the X.

Resolution:  I thought maybe I would try to clear the chart entirely before using the .databind() method.  To my surprise, this worked!  However, the results displayed left much to be desired.  The chart remained a line chart, but it now had 3 series of data (the initial one had only one series).  I thought then that maybe the idea would be to NOT clear the chart, but rather remove the series and then repopulate with a new series.  This rendered the proper data points, but for whatever reason, this made the chart default type a Bar Chart.  It also displayed the series labels again, which I did not want displayed.  I handled this with 2 lines of code following the rebinding of the datasource. 

Below is the code as I have in my LstShape_SelectedIndexChanged event:

     'create new series for the chart
        Dim series As New Telerik.Charting.ChartSeries
        Try
            'remove all existing chart series
            RadChart1.Series.Clear()
            'map series values
            series.DataXColumn = Me.AISCDataSet.ChartDimensions.Columns(1).ColumnName
            series.DataYColumn = Me.AISCDataSet.ChartDimensions.Columns(2).ColumnName
            'add new series to chart
            RadChart1.Series.Add(series)
            'rebind data
            RadChart1.DataBind()
            'reset chart type to LINE and remove series labels
            RadChart1.DefaultType = Telerik.Charting.ChartSeriesType.Line
            RadChart1.Series(0).Appearance.LabelAppearance.Visible = False
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

I hope this can be of some assistance.  If there is an easier workaround than the one I have provided, please let me know!

[Dwight]

Hi Michelle,

I am glad you have found a solution to the problem. I would just suggest, instead of changing the RadChart.DefaultType, to just set the series.Type to Bar and hide the labels before data bind:

Dim series As New Telerik.Charting.ChartSeries
    Try
        'remove all existing chart series
        RadChart1.Series.Clear()

        'map series values
        series.DataXColumn = Me.AISCDataSet.ChartDimensions.Columns(1).ColumnName
        series.DataYColumn = Me.AISCDataSet.ChartDimensions.Columns(2).ColumnName

        'set series type
        series.Type = ChartSeriesType.Line

        'hide labels
        series.Appearance.LabelAppearance.Visible = False

        'add new series to chart
        RadChart1.Series.Add(series)
        'rebind data
        RadChart1.DataBind()

    Catch ex As Exception
        MsgBox(ex.Message)
    End Try

Best,
Evtim
the Telerik team

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[Michelle]

Thanks!