选择IEnumerable <object> 来自IEnumerable <IEnumerable<object> &gt; linq

Question

What I need to do is select list of nested elements, here is my query which returns IEnumerable<IEnumerable<object>> here is my linq expression:

from a in (questions.Select(x => x.AnswerList).ToList())
                           select a.Select(x => x.AnswerBasicViewModel);

How should I do that to make it return only IEnumerable<object> instead of IEnumerable<IEnumerable<object>> ?

Just to be clear in my sample I would like to get IEnumerable<AnswerBasicViewModel> .

Answer 1

Use SelectMany operator:

from q in questions
from a in q.AnswerList
select a.AnswerBasicViewModel

Or simply

questions.SelectMany(q => q.AnswerList)
         .Select(a => a.AnswerBasicViewModel)

Answer 2

SelectMany是去这里的方式：

questions.SelectMany(x => x.AnswerList).Select(x => x.AnswerBasicViewModel);