CODEWITHSUNDEEP
c#genericsienumerable
Yippie-Ki-Yay
Yippie-Ki-Yay

Reputation: 22854

How can I create a singleton IEnumerable?

Does C# offer some nice method to cast a single entity of type T to IEnumerable<T>?

The only way I can think of is something like:

T entity = new T();
IEnumerable<T> = new List { entity }.AsEnumerable();

And I guess there should be a better way.

Upvotes: 18

Views: 6429

Answers (4)

n0099
n0099

Reputation: 1393

With the new collection expression that introduced in C# 12:

var singleton = [entity];

Just like the plain Dim singleton = { entity } in VB.NET: How can I create a singleton IEnumerable?

Upvotes: 0

Adam Robinson
Adam Robinson

Reputation: 185693

Your call to AsEnumerable() is unnecessary. AsEnumerable is usually used in cases where the target object implements IQueryable<T> but you want to force it to use LINQ-to-Objects (when doing client-side filtering on a LINQ-compatible ORM, for example). Since List<T> implements IEnumerable<T> but not IQueryable<T>, there's no need for it.

Anyway, you could also create a single-element array with your item;

IEnumerable<T> enumerable = new[] { t };

Or Enumerable.Repeat

IEnumerable<T> enumerable = Enumerable.Repeat(t, 1);

Upvotes: 25

LukeH
LukeH

Reputation: 269578

var entity = new T();
var singleton = Enumerable.Repeat(entity, 1);

(Although I'd probably just do var singleton = new[] { entity }; in most situations, especially if it was only for private use.)

Upvotes: 6

Mike Two
Mike Two

Reputation: 46193

I use

Enumerable.Repeat(entity, 1);

Upvotes: 6

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