Like Operator in Entity Framework?

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.

Solution 1:

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 :)

Solution 2:

This is an old post now, but for anyone looking for the answer, this link should help. Go to this answer if you are already using EF 6.2.x. To this answer if you're using EF Core 2.x

Short version:

SqlFunctions.PatIndex method - returns the starting position of the first occurrence of a pattern in a specified expression, or zeros if the pattern is not found, on all valid text and character data types

Namespace: System.Data.Objects.SqlClient Assembly: System.Data.Entity (in System.Data.Entity.dll)

A bit of an explanation also appears in this forum thread.

Solution 3:

I had the same problem.

For now, I've settled with client-side Wildcard/Regex filtering based on http://www.codeproject.com/Articles/11556/Converting-Wildcards-to-Regexes?msg=1423024#xx1423024xx - it's simple and works as expected.

I've found another discussion on this topic: http://forums.asp.net/t/1654093.aspx/2/10
This post looks promising if you use Entity Framework >= 4.0:

Use SqlFunctions.PatIndex:

http://msdn.microsoft.com/en-us/library/system.data.objects.sqlclient.sqlfunctions.patindex.aspx

Like this:

var q = EFContext.Products.Where(x =>
SqlFunctions.PatIndex("%CD%BLUE%", x.ProductName) > 0);

Note: this solution is for SQL-Server only, because it uses non-standard PATINDEX function.