CODEWITHSUNDEEP
razormodel-view-controllerchartsasp.net-webpages
ltree
ltree

Reputation: 53

Ensuring view controller method to get latest chart data is called whenever PartialView called

I am using Chart in Web.Helpers to render graphs for a view. The data set for this view can be distinguished by type into subsets, and the view allows the user to select a type.

My razor view containing this graph (_Chart.schtml) is simply:

<p>
<img src="/MyController/MyChart" />
</p>

The controller code (simplified)

public void MyChart()
{
  ChartSeries[] data = GetChartData(new string[] { _curChartDataType });
var chart =
                new Chart(500, 200, ChartTheme.Green);

                    for (int i=0; i<data.Length; i++) {
                        title += data[i].name + " ";
                        chart.AddSeries(name: data[i].name, chartType: "Line",                                                       
                           xValue: data[i].xValue, xField: data[i].xField,                
                           yValues: data[i].yValues, yFields: data[i].yFields);   
                    }
                    chart.AddTitle(title)
                    .AddLegend()
                    .Write("png");
}


public ActionResult ObjectList()
 {
            // irrelevant code removed

            return PartialView("_Chart");
}

In the parent view's cshtml, I use jquery to catch the user's change in type selection and invoke the call to MyController/ObjectList in ajax.

The graph renders properly when the view is first loaded. However, the user-invoked type changes result in a subsequent call to ObjectList (as expected), but MyChart() never gets called again after the first time.

Anything I should do to ensure MyChart() gets called again whenever PartialView("_Chart") is called? Any suggestions appreciated.

Upvotes: 1

Views: 35

Answers (2)

ltree
ltree

Reputation: 53

Okay, finally on a hunch, I made the following changes:

public WebImage MyChart()
{
  // same as before
  ...

  return chart.ToWebImage();
}

And guess what that was all it takes, for MVC's view engine to recognize that the chart object needs updating. The Chart object has a Write() method to write to its own internal structure (which somehow is made available as an image to the html), and ToWebImage() to write explicitly to a structure that the html can use in exactly the same way.. The difference being that the latter one knows to get updated. Go figure.

I hope this helps someone.

Upvotes: 0

Helen Araya
Helen Araya

Reputation: 1946

Make sure that JQuery isn't caching the results, on your ajax method, put the following:

$.ajax({
    cache: false
....
});

Upvotes: 0

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