我怎样才能.INCLUDE倒在LINQ多个级别？ [英] How can I .Include down more than one level in LINQ?

问题描述

我有以下类：

public class Problem : AuditableTable
{
    public Problem()
    {
        this.Questions = new List<Question>();
    }
    public int ProblemId { get; set; }
    public string Title { get; set; }
    public virtual ICollection<Question> Questions { get; set; }
}

public Question()
    {
        this.Answers = new List<Answer>();
    }
    public int QuestionId { get; set; }
    public int ProblemId { get; set; }
    public virtual ICollection<Answer> Answers { get; set; }
    public virtual Problem Problem { get; set; }
}
public class Answer : AuditableTable
{
    public int AnswerId { get; set; }
    public int QuestionId { get; set; }
    public string Text { get; set; }
    public virtual Question Question { get; set; }
}

我要发出这样的查询：

I want to issue a query like this:

        var problems = _problemsRepository.GetAll()
            .Where(p => p.ProblemId == problemId)
            .Include(p => p.Questions)
            .Include(p => p.Questions.Answers)
            .ToList();
        return problems;

所以我能看到问题，答问的信息。但是，有一个与我的最后一个问题包括，我无法工作，如何得到答案包括在内。

So I can see Problem, Question and Answer information. But there is a problem with my last include and I cannot work out how to get the Answers included.

有人可以给我一些这方面的建议。

Can someone give me some advice on this.

推荐答案

您。可以使用。选择（）

You can use .Select().

var problems = _problemsRepository.GetAll()
            .Where(p => p.ProblemId == problemId)
            .Include(p => p.Questions.Select(q => q.Answers))
            .ToList();

现在你的答案将包括在内。

Now your answers will be included.

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