如何使用LINQ在同一级别选择属性以及列表的其他项？

Question

I have a List of IJapaneseDictionaryEntry objects which are described below. Inside this are IKanji objects.

public interface IJapaneseDictionaryEntry
{
    int Sequence { get; }
    IEnumerable<IKanji> Kanjis { get; }
    IEnumerable<IReading> Readings { get; }
    IEnumerable<ISense> Senses { get; }
}

Where each object contains a list of IKanji objects

public interface IKanji
{
    string Text { get; }
    IEnumerable<KanjiInformation> Informations { get; }
    IEnumerable<Priority> Priorities { get; }
}

I selected the data with this query:

List<IJapaneseDictionaryEntry> entries = dictionary.GetEntries().ToList();

I know how to do a simple query like this:

var a = entries.SelectMany(x => x.Kanjis);

and how to select just the text:

var a = entries.SelectMany(x => x.Kanjis).Select(x => x.Text);

But what I would like to see the text and the priorities and I am not sure how to do that. What I would like to do is to get a flat output like this:

kanji1  ichimango1  Newspaper1  frequency10

How can I select, order and flatten out the priorities with a select?

Something like this:

var a = entries.SelectMany(x => x.Kanjis)
               .Select(x => x.Text, Priorities1, Priorities2, Priorities3);

Note that there may be no entry for Priorities1, Priorities2 or Priorities3

Answer 1

You would need to create an anonymous object with the properties you want to return:

var a = entries.SelectMany(x => x.Kanjis)
               .Select(x => new { x.Text, x.Priorities });

As per your EDIT: If you want to get only those Kanjis which have a Priority at all, you need to add a Where after the Select :

var a = entries.SelectMany(x => x.Kanjis)
               .Select(x => new { x.Text, x.Priorities })
               .Where(x => x.Priorities.Any());

However I would suggest to call ToList on x.Priorities in order to avoid iterating the same collection twice just to determine if there are elements at all. Technically you could also use the Where in front of the Select , but in this case you´d lose the ability to call ToList to avoid those multiple iterations.