How to use LINQ to reduce a <string,list<string>> to <string,string>?

Question

I'm calling a method with a return type of Dictionary<string, List<string>>.

The way i'm calling it i expect the List<string> to always have just 1 string element. To simplify this i'd like to use Linq to convert the return type to Dictionary<string, string>.

I got as far as to use .ToDictionary(x => x.Key, x=> x.Value); but i'm stumped on how to get the correct values. Is a conversion like this possible with LINQ?

Can't you modify the method that returns the Dictionary so that it returns Dictionary<string, string>? — Camilo Terevinto
– Camilo Terevinto, Commented Jul 5, 2016 at 14:27
It's a method in another program which i can't easily modify. — drouning
– drouning, Commented Jul 5, 2016 at 14:28

ocuenca · Accepted Answer · 2016-07-05 14:29:55Z

7

Try with:

.ToDictionary(x => x.Key, x=> x.Value.FirstOrDefault());

The value of your dictionary is a List<string>, so you can use IEnumerable<T> extension methods. Now there is several options to get the first element. Take a look this article for more details

edited Jul 5, 2016 at 14:29

answered Jul 5, 2016 at 14:27

ocuenca

39.5k12 gold badges95 silver badges107 bronze badges

Sign up to request clarification or add additional context in comments.

10 Comments

Jamie Rees Over a year ago

It might be good to explain the difference between using FirstOrDefault vs SingleOrDefault

Bradley Uffner Over a year ago

I'd suggest using .First instead of .FirstOrDefault. Since the OP always seems to expect one result, it would probably be better to have it throw an error if there are no results.

Jamie Rees Over a year ago

@BradleyUffner If they always expect one then Single should be used.

Camilo Terevinto Over a year ago

@JamieR I'd still use SingleOrDefault, just in case

Jamie Rees Over a year ago

@cFrozenDeath Depends on the requirements, from what OP has posted he only ever expects 1, so I would think Single would have been appropriate. But I understand, it's null vs exception.

|

Collectives™ on Stack Overflow

How to use LINQ to reduce a <string,list<string>> to <string,string>?

1 Answer 1

10 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

10 Comments

Your Answer

Sign up or log in

Post as a guest

Related