.Contains() in.Where() EF Core 不起作用 .NET Core 3.1.8

Question

I have the the following code that doesn't work:

var bookIds = source.Sids.Split(",");            
     
var hkm = _context.Books
                .Include(b => b.Writer)
                .Where(b => bookIds.Contains(b.SttmId.toString()))
                .ToList();

To clarify the code above a bit more:

// kinda same like the code above (just to clarify what source is):
// This doesn't work
 
var bookIds = "2194".Split(",");    
 
var hkm = _context.Books
                .Include(b => b.Writer)
                .Where(b => bookIds.Contains(b.SttmId.toString()))
                .ToList();
 
// This works
 
var bookIds = 2194;    
 
var hkm = _context.Books
                .Include(b => b.Writer)
                .Where(b => b.SttmId == bookIds))
                .ToList();

b.SttmId is of the type Nullable Long: long?

I get a strange error:

---> System.InvalidOperationException: The LINQ expression 'DbSet.Where(s => __BooksIds_0.Contains(b.SttmId.ToString()))' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly by inserting a call to either AsEnumerable(), AsAsyncEnumerable(), ToList(), or ToListAsync().

Am I doing something wrong or is there something wrong with EF Core?

Answer 1

This should work:

var bookIds = new long[] { 2194 };

var hkm = _context.Books
                  .Include(b => b.Writer)
                  .Where(b => bookIds.Any(x => x == b.SttmId))
                  .ToArray();

And if so all you have to do is arrange an array of longs eg

var bookIds = "1 2 3 4".Split().Select(x => long.Parse(x)).ToArray();

Answer 2

I ran similar code but without .Include(b => b.Writer) (thinks it doesn't matter) and it works. May be this depends on database management system or EntityFrameworkCore version? I use SQL server and EntityFrameworkCore 3.1.1