We're trying to implement the "LIKE" operator in Entity Framework for our entities with string fields, but it doesn't appear to be supported. Has anyone else tried to do something like this?
This blog post summarizes the issue we're having. We could use contains, but that only matches the most trivial case for LIKE. Combining contains, startswith, endswith, and indexof gets us there, but requires a translation between standard wildcards and Linq to Entities code.
I don't know anything about EF really, but in LINQ to SQL you usually express a LIKE clause using String.Contains:
where entity.Name.Contains("xyz")
translates to
WHERE Name LIKE '%xyz%'
(Use StartsWith and EndsWith for other behaviour.)
I'm not entirely sure whether that's helpful, because I don't understand what you mean when you say you're trying to implement LIKE. If I've misunderstood completely, let me know and I'll delete this answer :)
Update: In EF 6.2 there is a like operator
Where(obj => DbFunctions.Like(obj.Column , "%expression%"))
There is LIKE operator is added in Entity Framework Core 2.0:
var query = from e in _context.Employees
where EF.Functions.Like(e.Title, "%developer%")
select e;
Comparing to ... where e.Title.Contains("developer") ... it is really translated to SQL LIKE rather than CHARINDEX we see for Contains method.
It is specifically mentioned in the documentation as part of Entity SQL. Are you getting an error message?
// LIKE and ESCAPE
// If an AdventureWorksEntities.Product contained a Name
// with the value 'Down_Tube', the following query would find that
// value.
Select value P.Name FROM AdventureWorksEntities.Product
as P where P.Name LIKE 'DownA_%' ESCAPE 'A'
// LIKE
Select value P.Name FROM AdventureWorksEntities.Product
as P where P.Name like 'BB%'
For EfCore here is a sample to build LIKE expression
protected override Expression<Func<YourEntiry, bool>> BuildLikeExpression(string searchText)
{
var likeSearch = $"%{searchText}%";
return t => EF.Functions.Like(t.Code, likeSearch)
|| EF.Functions.Like(t.FirstName, likeSearch)
|| EF.Functions.Like(t.LastName, likeSearch);
}
//Calling method
var query = dbContext.Set<YourEntity>().Where(BuildLikeExpression("Text"));