Linq to SQL: Partial matching strings using contains on an array of strings

Question

Here is my code:

string[] customerNames = searchModel.CustomerName.Split(',');
 query = query.Where(d => customerNames.Contains(d.CustomerName, comparer) || customerNames.Contains(d.Company1.CompanyName, comparer));

Which works if you are just looking for exact matches. However I'd like to partial match, ie: if customerNames contains an element 'ell', it would select d if d.CustomerName was 'Hello' since 'ell' is in 'Hello'

I tried overriding the EqualityComparer, but I believe it is trying to use the GetHashCode function rather than the Equals in the Comparer, which I'm not sure how to implement.

How should I go about this?

GetHashCode is not guaranteed to prevent collisions so you can be sure there's more going on than that. — Casey
– Casey, Commented Feb 10, 2014 at 22:55

MarcinJuraszek · Accepted Answer · 2014-02-10 22:51:14Z

1

string[] customerNames = searchModel.CustomerName.Split(',');
query = query.Where(d => customerNames.Any(c => c.Contains(d.CustomerName)) || customerNames.Any(c => c.Contains(d.Company1.CompanyName)));

But you should be aware, that it may get really slow when customerNames has a lot of items.

answered Feb 10, 2014 at 22:51

MarcinJuraszek

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6 Comments

Dave Over a year ago

I just was answering this myself. I'll check you off when 8 minutes has passed. customerNames should be very few items, but yeah I'm not sure what I can do to avoid this logic.

Hamlet Hakobyan Over a year ago

Will it translated to sql or will executed on client side on full set?

MarcinJuraszek Over a year ago

You can use PredicateBuilder and just add list of OR conditions to your query. Which should probably be better and faster then Any+Contains chain.

MarcinJuraszek Over a year ago

@HamletHakobyan Should be transform into SQL (that's why I removed the comparer).

Hamlet Hakobyan Over a year ago

The expression tree would be better solution in this case.

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