Is there an efficient way in LINQ to use a contains match if and only if there is no exact match?
- by Peter
I have an application where I am taking a large number of 'product names' input by a user and retrieving some information about each product. The problem is, the user may input a partial name or even a wrong name, so I want to return the closest matches for further selection.
Essentially if product name A exactly matches a record, return that, otherwise return any contains matches. Otherwise return null.
I have done this with three separate statements, and I was wondering if there was a more efficient way to do this. I am using LINQ to EF, but I materialize the products to a list first for performance reasons.
productNames is a List of product names (input by the user).
products is a List of product 'records'
var directMatches = (from s in productNames
join p in products on s.ToLower() equals p.name.ToLower() into result
from r in result.DefaultIfEmpty()
select new {Key = s, Product = r});
var containsMatches = (from d in directMatches
from p in products
where d.Product == null
&& p.name.ToLower().Contains(d.Key)
select new { d.Key, Product = p });
var matches = from d in directMatches
join c in containsMatches on d.Key equals c.Key into result
from r in result.DefaultIfEmpty()
select new {d.Key, Product = d.Product ?? (r != null ? r.Product: null) };
