实体框架列表将所有属性返回到映射模型

Question

I have three classes: Students, Subjects and Grades.

public class Grades
{
    [Key]
    public int Id { get; set; }
    public Student Student { get; set; }
    public Subject Subject { get; set; }
    public int Year { get; set; }
    public string Grade { get; set; }
}

Student Class

 public class Student
    {
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public string Gender { get; set; }
        public string Nationality { get; set; }
    }

Subject Class

public class Subject
{
    [Key]
    public int Id { get; set; }
    public string Title { get; set; }
}

I want to return all Grades but with properties of Student and Subject expanded, like I can access Grade.Name

Grade.Gender

Grade.Nationality

Grade.Year

Grade.Grade

instead of Grade.Student.Name

Grade.Student.Gender

Grade.Student.Nationality

Answer 1

Use these expressions to expand your data. Note that they will not be of the Grade class but they will be anonymous class with properties you want. If you need to pass these items to other methods, you have to create explicit class that has these properties. Otherwise you may access them directly in the same method. Like, expandedGrades.First().Name .

var expandedGrades =
    DBContext.Grades.Select(grade =>
    new
    {
        Name = grade.Student.Name,
        Gender = grade.Student.Gender,
        Nationality = grade.Student.Nationality,
        Year = grade.Year,
        Grade = grade.Grade
    });

or

var expandedGrades =
                from grade in DBContext.Grades
                select new
                {
                    Name = grade.Student.Name,
                    Gender = grade.Student.Gender,
                    Nationality = grade.Student.Nationality,
                    Year = grade.Year,
                    Grade = grade.Grade
                };

Answer 2

Assuming you have proper relationships set between your Students, Subjects and Grades tables. In Entity framework you can use .include to get your job done.

A basic example:

Blog blogs = context.Blogs 
                    .Include(b => b.Posts) 
                    .ToList(); 

with this now you can use blogs.Posts directly.

Reference : https://msdn.microsoft.com/en-in/data/jj574232.aspx