Question

I just read this question and it got me thinking of why I would need to use the IEnumerable when retrieving data. I understand the differences between IQueryable and IEnumerable, but would an IEnumerable object be better for data that allows filtering? for example, a table with the records which contain a date, so I can sort on the date.

Answer 1

If you have the objects in memory – not from another data source such as a database – use IEnumerable<T>. That way the built in LINQ to Objects will work automatically.

You could even extend LINQ to Objects by writing custom extension methods and using yield return and yield break.

If you are using Entity Framework or some other system that is using IQueryable<T>, I would keep it as IQueryable<T> until you need it as objects.