Question

I am using complicated SQL queries, i have to use SqlQuery … in simple way:

MODEL:

public class C
{
    public int ID { get; set; }
    [NotMapped]
    public float Value { get; set; }
}

CONTROLLER:

IEnumerable<C> results = db.C.SqlQuery(@"SELECT ID, ATAN(-45.01) as Value from C);
return View(results.ToList());

VIEW:

@model IEnumerable<C>
@foreach (var item in Model) {
    @Html.DisplayFor(modelItem => item.Value)
}

and the result for item.Value is NULL.

So my question is , how can i print the computed value from SQL Query ?

Thank you for help.

Answer 1

I would conclude from the fact that Value is 0 that EF doesn’t map returned columns to properties that are not mapped in the model.

What you could try as an alternative is to define a helper type…

public class CHelper
{
    public int ID { get; set; }
    public float Value { get; set; }
}

Then query into this type and copy the values to your entity afterwards:

IEnumerable<C> results = db.Database.SqlQuery<CHelper>(
    @"SELECT ID, ATAN(-45.01) as Value from C")
    .Select(ch => new C
    {
        ID = ch.ID,
        Value = ch.Value
    });

(Normally in a LINQ-to-Entities query you cannot project into an entity with Select. But I believe that the Select in the example above does not affect the database query and is LINQ-to-Objects in memory, so it should be allowed. I am not sure, though.)

Note that the results collection is not attached to and tracked by the context, but I guess you don’t need it anyway for a GET request to render a view.

Of course you could create your view directly based on the CHelper class as view model and omit the conversion into the C entity.