C#•2y ago

❔ ❔ MVC - Chart - Model - NullReferenceException

I'm using google chart to display my data. The chart works by default, but when I change the foreach data dispay, it disappears. @model List<BloodSugarData> ...

      function drawStuff() {

        var button = document.getElementById('change-chart');
        var chartDiv = document.getElementById('chart_div');

        var data = google.visualization.arrayToDataTable([

        @Html.Raw($"['User Phone', 'Date', 'Time of Day', 'Blood Sugar (mg/dl)'],")
        @foreach (var item in Model)
        {
            @Html.Raw($"['{@item.userPhone}', {@item.measureDate}, {@item.timeOfDay}, {@item.mgBloodSugar}],")
        }
        ]);

      function drawStuff() {

        var button = document.getElementById('change-chart');
        var chartDiv = document.getElementById('chart_div');

        var data = google.visualization.arrayToDataTable([

        @Html.Raw($"['User Phone', 'Date', 'Time of Day', 'Blood Sugar (mg/dl)'],")
        @foreach (var item in Model)
        {
            @Html.Raw($"['{@item.userPhone}', {@item.measureDate}, {@item.timeOfDay}, {@item.mgBloodSugar}],")
        }
        ]);

20 Replies

cyb3rdragonOP•2y ago

The problem should be in the foreach line imo, but I don't know what +picture: the data shows up when I only use the same foreach in a table, but I need it in a chart

cyb3rdragonOP•2y ago

Update: System.NullReferenceException - Model

Angius•2y ago

Show your backend code

cyb3rdragonOP•2y ago

Data class (Model)

cyb3rdragonOP•2y ago

BSDiagram Razor View

cyb3rdragonOP•2y ago

I can send code format too if needed

Angius•2y ago

And the controller?

cyb3rdragonOP•2y ago

public ActionResult BSDiagram()
        {
            return View();
        }

public ActionResult BSDiagram()
        {
            return View();
        }

Angius•2y ago

Well

cyb3rdragonOP•2y ago

I have to add the data into the controller< ?

Angius•2y ago

You're not sending any data to the view So hard to expect it to be there

cyb3rdragonOP•2y ago

okay understand

Angius•2y ago

Whatever you pass to View() is available as Model in the view The @model Foo in the view just tells it that the type of that Model will be Foo

cyb3rdragonOP•2y ago

cool! thank you, I just got confused haha

cyb3rdragonOP•2y ago

🙂

Angius•2y ago

Nice

cyb3rdragonOP•2y ago

@model List<BloodSugarData>


<table>
    <tr>
        <th> Id </th>
        <th> Phone </th>
        <th> Date </th>
        <th> Time of day </th>
        <th> Blood sugar (mg/dl)</th>
    </tr>

@{
    for (int i = 0; i < Model.Count; i++)
    {
        var item = Model[i];

        <tr>
            <td>@item.Id </td>
            <td>@item.userPhone </td>
            <td>@item.measureDate </td>
            <td>@item.timeOfDay </td>
            <td>@item.mgBloodSugar </td>

        </tr>
</table>
    }
}

@model List<BloodSugarData>


<table>
    <tr>
        <th> Id </th>
        <th> Phone </th>
        <th> Date </th>
        <th> Time of day </th>
        <th> Blood sugar (mg/dl)</th>
    </tr>

@{
    for (int i = 0; i < Model.Count; i++)
    {
        var item = Model[i];

        <tr>
            <td>@item.Id </td>
            <td>@item.userPhone </td>
            <td>@item.measureDate </td>
            <td>@item.timeOfDay </td>
            <td>@item.mgBloodSugar </td>

        </tr>
</table>
    }
}

        public IActionResult BSMeasurePageList()
        {
            return View(bsDatas);
        }

        public IActionResult BSMeasurePageList()
        {
            return View(bsDatas);
        }

        public static List<BloodSugarData> bsDatas = new List<BloodSugarData>
        {

            new BloodSugarData(0, "36703245432", date1, "morning", 4),
            new BloodSugarData(1, "36405555555", date2, "night", 12),

        };

        public static List<BloodSugarData> bsDatas = new List<BloodSugarData>
        {

            new BloodSugarData(0, "36703245432", date1, "morning", 4),
            new BloodSugarData(1, "36405555555", date2, "night", 12),

        };

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

cyb3rdragonOP•2y ago

/close

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ ❔ MVC - Chart - Model - NullReferenceException