Razor foreach loop and javascript

Question

Please help. I am getting a headache with razor. I am trying to use google charts to display my information.

So, this is what I have in my view:

@section scripts
{
    <script type="text/javascript" src="https://www.google.com/jsapi"></script>
    <script type="text/javascript">
        google.load("visualization", "1", { packages: ["corechart"] });
        google.setOnLoadCallback(drawChart);
        function drawChart() {
            var data = google.visualization.arrayToDataTable([
          ['Date', 'DDM'],
                @foreach(var item in Model.ToList())
                {
                    <text>
                        ['item.Item1', 'item.Item2']
                    </text>
                }
        ]);

            var options = {
                title: 'Demande de marché',
                hAxis: { title: 'Date', titleTextStyle: { color: '#333'} }
            };

            var chart = new google.visualization.AreaChart(document.getElementById('chart_div'));
            chart.draw(data, options);
        }
    </script>
}

I use the foreach loop to iterate on the model (IEnumerable<Tuple<DateTime,int>>) to add the information in the javascript function. At design time, I get

Conditional compilation is turned off

Does anyone know how to solve this?

Thanks

Edit: This is the controller:

public ActionResult DDMPerDepartment(string department)
        {
            if (DepartmentsList == null) DepartmentsList = _db.Departments.ToList();
            ViewBag.DepartmentString = DepartmentsList.First().DepartmentName;

            IEnumerable<Tuple<DateTime,int>> points = _db.DepartmentNumbers.Where(x => x.Department.Id == 1).Select(x => new Tuple<DateTime, int>(x.Date, x.Number));
            return View(points);
        }

possible duplicate of Conditional Compilation is turned off in Razor? — Kamil Budziewski
– Kamil Budziewski, Commented Dec 12, 2013 at 14:55

odyss-jii · Accepted Answer · 2013-12-12 15:16:33Z

3

You have some errors in the code:

You are putting the string 'item.Item1' instead of the value of property Item1 of the variable item. Use '@(item.Item1)' instead.
You are missing a comma at the end of each item in the foreach loop. The injected javascript is therefore invalid. You need

<text>['@(item.Item1)', '@(item.Item2)'],</text>

EDIT:

OK, so the problem is in the LINQ to entities query above.

IEnumerable<Tuple<DateTime,int>> points = _db.DepartmentNumbers.Where(x => x.Department.Id == 1).Select(x => new Tuple<DateTime, int>(x.Date, x.Number));

The entity framework needs to be able to convert this query to a SQL query, and therefore does not accept the use of constructors with parameters within the query. The Where and Select clauses above are combined into one SQL query.

A possible workaround is to first evaluate the part of the expression that needs to run on the database, get the data back to memory, and then create the tuples in memory. There are many overloads of the LINQ methods, some of these create expressions for LINQ to entities, some perform LINQ operations in memory. You need to make sure that the select which creates the tuple is executed in memory, i.e. you do not want the overload which applies to IQueryable<T>.

IEnumerable<Tuple<DateTime,int>> points = _db.DepartmentNumbers
    .Where(x => x.Department.Id == 1)  // LINQ to Entities WHERE
    .Select(x => new { x.Date, x.Number })  // LINQ to Entities SELECT
    .AsEnumerable()  // We want the next statement to be a select on IEnumerable instead of IQueryable.
    .Select(x => new Tuple<DateTime, int>(x.Date, x.Number)); // In-memory SELECT

edited Dec 12, 2013 at 15:16

answered Dec 12, 2013 at 14:59

odyss-jii

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3 Comments

Daniel Over a year ago

I get the error on the foreach statement. And I still have the problem. At runtime, I have an exception at the foreach line stating "Only parameterless constructors and initializers are supported in LINQ to Entities."

odyss-jii Over a year ago

I see, so the problem is perhaps in your model then. Can you post the code of the model?

Daniel Over a year ago

In the controller, if I do "points = _db.DepartmentNumbers.[...].ToList()" I have the same error but in the model

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