如何获取具有多对多关系的相关数据？

Question

我有模型 Project 和 Programmer 具有多对多关系：

public class Project
{
    public Project()
    {
        ProjectProgrammers = new HashSet<ProjectProgrammer>();
    }
    public int ProjectID { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public virtual ICollection<ProjectProgrammer> ProjectProgrammers { get; set; }
}

public class Programmer
{
    public Programmer()
    {
        ProjectProgrammers = new HashSet<ProjectProgrammer>();
    }

    public int ProgrammerID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string DisplayName { get; set; }

    public virtual ICollection<ProjectProgrammer> ProjectProgrammers { get; set; }
}

有模型ProjectProgrammer：

public class ProjectProgrammer
{
    public int ProjectID { get; set; }
    public virtual Project Project { get; set; }

    public int ProgrammerID { get; set; }
    public virtual Programmer Programmer { get; set; }
}

配置：

        modelBuilder.Entity<ProjectProgrammer>()
            .HasKey(pp => new { pp.ProjectID, pp.ProgrammerID });

        modelBuilder.Entity<ProjectProgrammer>()
            .HasOne(pp => pp.Project)
            .WithMany(p => p.ProjectProgrammers)
            .HasForeignKey(pp => pp.ProjectID);

        modelBuilder.Entity<ProjectProgrammer>()
            .HasOne(pp => pp.Programmer)
            .WithMany(p => p.ProjectProgrammers)
            .HasForeignKey(pp => pp.ProgrammerID);

当我尝试使用 Include() 和 Theninclude() 加载相关数据时：

    public async Task<IEnumerable<Project>> ListAsync()
    {
        return await _context.Projects.Include(p => p.ProjectProgrammers)
                                      .ThenInclude(pp => pp.Programmer)
                                      .ToListAsync();
    }

我只得到第一条程序员信息不完整的记录：

[{"projectID":100,"name":"Project1","description":"Desc","projectProgrammers":[{"projectID":100

Answer 1

我通过向其中一个导航 属性 添加 [JsonIgnore] 属性解决了这个问题。更多信息：http://ericsmasal.com/2018/01/04/ef-core-and-defeating-the-self-referencing-loop/