Question

I have the following lambda expression:

string queryToken = queryTokens.Last();
var result = from locationAddress in locations
             let tokens = GetLetterTokens(locationAddress.Name)
             let distance = (from token in tokens
                             where token.Contains(queryToken, StringComparison.OrdinalIgnoreCase)
                             select token.Length - queryToken.Length).Min()
             orderby distance
             select new
                        {
                            LocationAddress = locationAddress,
                            LocationDistance = distance,
                        };

It doesn’t matter what it’s written for. Sometimes when counting distance, there are no tokens containing queryToken, so .Min() couldn’t be returned. How to skip these cases? I don’t want to add them into result variable.

Answer 1

Sounds like you just want:

let tokens = ...
where tokens.Any(token.Contains(queryToken, StringComparison.OrdinalIgnoreCase))
let distance = ...

Alternatively, just filter when you select the tokens, and then check whether any exist:

var result = from locationAddress in locations
             let tokens = GetLetterTokens(locationAddress.Name)
                              .Where(token => token.Contains(queryToken, StringComparison.OrdinalIgnoreCase)
             where tokens.Any()
             let distance = tokens.Min(token => token.Length - queryToken.Length)