Remove objects with a duplicate property from List

Question

I have a List of objects in C#. All of the objects contain a property ID. There are several objects that have the same ID property.

How can I trim the List (or make a new List) where there is only one object per ID property?

[Any additional duplicates are dropped out of the List]

Answer 1

If you want to avoid using a third-party library, you could do something like:

var bar = fooArray.GroupBy(x => x.Id).Select(x => x.First()).ToList(); 

That will group the array by the Id property, then select the first entry in the grouping.

Answer 2

MoreLINQ DistinctBy() will do the job, it allows using object proeprty for the distinctness. Unfortunatly built in LINQ Distinct() not flexible enoght.

var uniqueItems = allItems.DistinctBy(i => i.Id); 

DistinctBy()

Returns all distinct elements of the given source, where "distinctness" is determined via a projection and the default eqaulity comparer for the projected type.

• Download MoreLINQ
• DistinctBy() sources

PS: Credits to Jon Skeet for sharing this library with community