c# Build Error with LINQ syntax in Controller

Question

Hi folks I have the following error on line 11 in this controller code :

    public JsonResult GetChartData_IncidentsBySiteStatus(string SiteTypeId, string searc         


        

Answer 1

You are trying to assign a base class instance to a sub class instance.

Instead of

var sitesQry = _db.Sites;

try using

IQueryable<Site> sitesQry = _db.Sites;

Answer 2

While @Eranga 's solution may work, I feel as though there are more options and a better explanation available.

Firstly, the reason that you cannot assign the value is because you are trying to assign and implementation of an interface to a concrete type. THis cannot be done because you have no idea what could be implementing that interface, and this means that the it cannot be assigned to something that has a concrete type.

There are multiple options for this. You can do as @Eranga suggests and create a new variable

IQueryable<Site> sitesQry = _db.Sites;

or you can call the .CopyToDataTable extension method that is exposed by Linq.

sitesQry = _db.Sites.CopyToDataTable();