Как я могу достичь этого в ASP.NET сердечник

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Как вернуть несколько сущностей для веб-api. я застрял здесь на 3 дня.

public partial class Regions
    {
        public Regions()
        {
            Projects = new HashSet<Projects>();
            RegionUserRelation = new HashSet<RegionUserRelation>();
        }

        public int RegionId { get; set; }
        [Required]
        public string RegionName { get; set; }
        [Required]
        public string RegionFullname { get; set; }
        [Required]
        public int RegionTypeId { get; set; }
        public string RegionMisc { get; set; }

        public RegionType RegionType { get; set; }
        public ICollection<Projects> Projects { get; set; }
        public ICollection<RegionUserRelation> RegionUserRelation { get; set; }
    }

public partial class Projects
    {
        public Projects()
        {
            Sections = new HashSet<Sections>();
        }

        public Guid ProjectId { get; set; }
        [Required]
        public string ProjectName { get; set; }
        [Required]
        public string ProjectCode { get; set; }
        public string ProjectDesc { get; set; }
        [Required]
        public int RegionId { get; set; }
        [Required]
        public int EpsgId { get; set; }

        public Epsg Epsg { get; set; }
        public Regions Region { get; set; }
        public ICollection<Sections> Sections { get; set; }
    }


public partial class Sections
    {
        public Sections()
        {
            Flights = new HashSet<Flights>();
        }

        public Guid SectionId { get; set; }
        [Required]
        public string SectionName { get; set; }
        public string SectionDesc { get; set; }
        [Required]
        public Guid ProjectId { get; set; }

        public Projects Project { get; set; }
        public ICollection<Flights> Flights { get; set; }
    }

Ожидаемый результат

{ "Regions" : 
  [ { 
		"region_id" : "2012",
		"region_name" : "region1",
		"region_fullname" : "21700",
		"region_type" : "MERCH",
			"Projects" : [ 
			   {     "project_id" : 2341,
					 "project_name " : "DXY",
					 "project_code " : "21700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			"Projects" : [ 
			   {     "project_id" : 1321,
					 "project_name " : "Proj_2",
					 "project_code " : "01700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			]
  },
  { 
		"region_id" : "2013",
		"region_name" : "region3",
		"region_fullname" : "21330",
		"region_type" : "MERCH",
			"Projects" : [ 
			   {     "project_id" : 2341,
					 "project_name " : "DXY",
					 "project_code " : "21700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			"Projects" : [ 
			   {     "project_id" : 1321,
					 "project_name " : "Proj_2",
					 "project_code " : "01700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			]
  },
  { 
		"region_id" : "2012",
		"region_name" : "region2",
		"region_fullname" : "24300",
		"region_type" : "MERCH",
			"Projects" : [ 
			   {     "project_id" : 2341,
					 "project_name " : "DXY",
					 "project_code " : "21700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			"Projects" : [ 
			   {     "project_id" : 1321,
					 "project_name " : "Proj_2",
					 "project_code " : "01700",
					 "sections" : [
								{ "section_id" : 4356,
								"section_name" : sec_name,
								"section_description" : sec_dis},
								{ "section_id" : 476,
								"section_name" : sec_name2,
								"section_description" : sec_dis2},
								{ "section_id" : 908,
								"section_name" : sec_name3,
								"section_description" : sec_dis3}
							]
				},
			]
  },
] }

Что я уже пробовал:

try
            {
                using (var entities = new POCContext())
                {
                    var q = (from d in entities.Regions
                             join c in entities.Projects on d.RegionId equals c.RegionId
                             join s in entities.Sections on c.ProjectId equals s.ProjectId
                             select d);

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