Question

这就是我的数据库代码：

public class Question {
    public int Id {get; set;}
    public ICollection<Answer> Answers {get; set;}

    public Question() {
        Answers = new List<Answer>();
    }
}

public class Answer {
    public ind Id {get; set;}
    public string Message {get; set;}

    public int QuestionId { get; set; }
    [ForeignKey("QuestionId")]
    public Question Question { get; set; }

    public int? PictureId { get; set; }
    [ForeignKey("PictureId")]
    public Picture Picture { get; set; }

    public int KeywordId { get; set; }
    [ForeignKey("KeywordId")]
    public Keyword Keyword { get; set; }

    public int? VideoId { get; set; }
    [ForeignKey("VideoId")]
    public Video Videos { get; set; }
}

public class Picture {
    public int Id {get; set;}
    public string Url {get; set;}
}

public class Keyword {
    public int Id {get; set;}
    public string Text {get; set;}
}

public class Video {
    public int Id {get; set;}
    public string Url {get; set;}
}

我想要存档的是加载带有图片和关键字的答案的所有问题（我不想加载Video。此代码：

public static List<Question> GetQuestions() {
    using (var context = new DatabaseContext()) {
        return context.Questions
            .Include(x => x.Answers.Select(y => y.Keyword))
            .ToList();
    }
}

用关键字向我提出所有答案的所有问题。我真的不知道如何附上图片。我认为有更好的方法来做到这一点，而不是逐个选择所有对象（我仍然不确定是否可能）。你能帮帮我吗？

Answer 1

您可以使用Include的重载，允许您使用表示您可能需要的任何属性的字符串。

context.Questions.Include("Answers.Picture")
                 .Include("Answers.Keyword")
                 .ToList();

Answer 2

只需尝试：

return context.Questions
.Include(x => x.Answers.Select(y => y.Keyword))
.Include(x => x.Answers.Select(y => y.Picture))
.ToList();

或使用最后选择的投影（无论如何都会忽略所有包含）：

return context.Questions
.Select(x => new Answers(){x.Keyword,x.Picture }
.ToList();

包括多个级别的对象

2 个答案: