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 searchTextSite, string StartDate, string EndDate)
    {
        if (searchTextSite == null)
            searchTextSite = "";

        DateTime startDate = DateTime.Parse(StartDate);
        DateTime endDate = DateTime.Parse(EndDate);

        var sitesQry = _db.Sites;
        if (SiteTypeId != "-1")
            sitesQry = sitesQry.Where(a => a.SiteTypeId.ToString() == SiteTypeId);

        var qry = from i in _db.Incidents   
                  join s in _db.Sites on i.SiteId equals s.SiteId
                  where s.SiteDescription.Contains(searchTextSite)
                    && (i.Entered >= startDate && i.Entered <= endDate)
                  group s by s.SiteStatus.SiteStatusDescription + "[" + s.SiteTypeId.ToString() + "]"
                      into grp
                      select new
                      {
                          Site = grp.Key,
                          Count = grp.Count()
                      };

        return Json(qry.ToList()  , JsonRequestBehavior.AllowGet);
    }

...........the error is:

Error 7 Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Data.Linq.Table'. An explicit conversion exists (are you missing a cast?) C:\Documents and Settings\Administrator\Desktop\IRenewables_EMAS\IRenewables_EMAS\Controllers\IncidentController.cs 69 28 Emas.Web

Can anyone suggest a workaround for this?

thanks

Which line exactly is line 11? The casting is incorrect, and that particular IQueryable object is not providing an Table interface. — Alex R.
– Alex R., Commented Jul 11, 2011 at 8:21
Line 11: sitesQry = sitesQry.Where(a => a.SiteTypeId.ToString() == SiteTypeId); — John
– John, Commented Jul 11, 2011 at 8:52
why not get rid of that line and in your query go : where (s.SiteId.Equals(SiteTypeId) && !s.SiteId.Equals("-1") ... — dreza
– dreza, Commented Jul 11, 2011 at 9:12
Alternatively you could potentially go var sitesQry = _db.Sites.AsQueryable(); ... — dreza
– dreza, Commented Jul 11, 2011 at 9:20

Eranga · Accepted Answer · 2011-07-11 09:18:43Z

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;

answered Jul 11, 2011 at 9:18

Eranga

32.5k5 gold badges100 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

David Pilkington Over a year ago

While you suggestion is correct, I feel as though your explanation is not. IQueryable is not a base class, its an interface. This means that, while the Table class may implement the interface, calling it a base/sub class relationship is fundamentally incorrect.

David Pilkington · Accepted Answer · 2017-01-03 11:36:24Z

0

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();

answered Jan 3, 2017 at 11:36

David Pilkington

13.6k3 gold badges44 silver badges75 bronze badges

Collectives™ on Stack Overflow

c# Build Error with LINQ syntax in Controller

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related