使用Linq / Lambda在CSV列上使用String.Split（）。Contains（）

Question

I have a database table column that contains a comma separated list of strings. I need to query this table for a string within the comma separated column.

The table:

public class MyObject
{
    public string sIds { get; set; }

    ...
}

If the sIds column in my table contains:

sIds = "DG,VO,XX,AB"

and I execute the following code:

string _sId = "AB";

List<MyObject> designParams = _context.DesignParams
    .AsNoTracking()
    .Where(c => c.sIds.Split(',').Contains(_sId))
    .Select(c => c)
    .ToList();

I get NotSupportedException: LINQ to Entities does not recognize the method 'System.String[] Split(Char[])' method, and this method cannot be translated into a store expression. .

There's a lot of articles similar to my issue, but I haven't been able to find an exact solution. Is there something wrong with my code or is there a different way this should be done?

Answer 1

String.Split is not supported by EF. This is because there is no equivalent in SQL. You can try to define your own function in database like described here: http://sqlperformance.com/2012/07/t-sql-queries/split-strings . Or you can try move part of logic from server to client.

Answer 2

The equivalent in SQL is "IN", the Contains in LINQ is a bit like reverse:-

List<MyObject> designParams = _context.DesignParams
.AsNoTracking()
.Where(c => _sId.Contains(c.sIds))
.Select(c => c)
.ToList();