Question

I want to use something like “In clause” of SQL SERVER.
Here are my models:

public partial class StationEvaluationBooks
{
    public int StationEvaluationBookID { get; set; }
    public Nullable<int> StationEvaluationID { get; set; }

    public virtual StationEvaluation StationEvaluation { get; set; }
    ...
 }
public partial class StationEvaluation
{
    public StationEvaluation()
    {
        this.StationEvaluationBooks = new HashSet<StationEvaluationBooks>();
    }
    public int StationEvaluationID { get; set; }
    public virtual ICollection<StationEvaluationBooks> StationEvaluationBooks { get; set; }
    ...
 }

I used the following code to implement “In clause” by LINQ but I got error:

        StationsEntities db = new StationsEntities();

        var stationevaluations = db.StationEvaluation;
       //some conditions:
        stationevaluations = stationevaluations.Where(/*condition*/);
       ..

        var result = from c in db.StationEvaluationBooks
                       where stationevaluations.Contains(c.StationEvaluationID)
                       select c;

Error: ‘System.Data.Entity.DbSet’ does not contain a definition for ‘Contains’ and the best extension method overload ‘System.Linq.ParallelEnumerable.Contains(System.Linq.ParallelQuery, TSource)’ has some invalid arguments

EDIT:
I want to get those books that are related to the selected evaluations in stationevaluations variable.

Answer 1

Getting books related to selected stations:

var ids = db.StationEvaluation.Where(/*condition*/)
            .Select(s => s.StationEvaluationID)
            .ToList();

var result = from b in db.StationEvaluationBooks
             where b.StationEvaluationID.HasValue &&
                   ids.Contains(b.StationEvaluationID.Value)
             select b;

Or best option

var result = db.StationEvaluation.Where(/*condition*/)
               .SelectMany(s => s.StationEvaluationBooks);