C# lambda IN clause error

I’m having issues creating an IN clause using C# and lambdas.

I have the following method GetUserList(string filtersByRoles)

The variable string filtersByRoles can hold a comma-delimited value such as: “1,2” or “1,2,3” or “1,3,4” etc...each number represents the unique number of a Role (in other words, RoleId).

I then have the following C# lambda query:

var query = _userRepository.GetUserList();

Which returns an IQueryable<User> where User is a table from my EntityFramework.

Once I verify if the filtersByRoles parameter is not null-or-empty, I need to make an IN clause such as:

if (!string.IsNullOrEmpty(filtersByRoles))
{
   //Convert *filtersByRoles* to an array of integers
   int[] myArray = filtersByRoles.Split(',').Select(x => int.Parse(x)).ToArray();

   //Make the IN clause
   query = query.Where(u => myArray.Contains(u.RoleId));
}

The above code compiles...but at RUNTIME it fails with the following error message:

LINQ to Entities does not recognize the method 'Boolean Contains[Int32](System.Collections.Generic.IEnumerable`1[System.Int32], Int32)' method, and this method cannot be translated into a store expression.

I’ve manage to find a workaround but it involves making a call to the .ToList() method which I believe fetches all the data from my database and then, adds a Where() clause. But wouldn’t that defeat the purpose or create some performance issues?

This is what I’ve done:

if (!string.IsNullOrEmpty(filtersByRoles))
{
      string[] myArray = filtersByRoles.Split(',');
      query = query.ToList().Where(u => myArray.Contains(u.RoleId.ToString())).AsQueryable();
}

I would prefer not to make the .ToList() call and avoid fetching all the data.

Is there another way to achieve this?

EDIT: I'm using Entity Framework 1.0 and .NET Framework 3.5

Thanks Sincerely

Vince