EF循环依赖

本是古典何须时尚 2024-04-07 14:28 64阅读 0赞

## 1.项目场景： ##

项目场景：

1.本项目采用了EF架构来建立实体与实体之间的关联关系。

2.一个部门对应多个摄像头

> 1.部门实体：

public partial class DepartmentEntity		//部门实体
        {
         
            public int Id {
         get; set; }
            public virtual ICollection< CameraEntity> lstCamera {
         get; set; }
            /// <summary>
            /// 部门编码
            /// </summary>
            public string DeptCode {
         get; set; }
            /// <summary>
            /// 部门名称
            /// </summary>
            public string DeptName {
         get; set; }
            /// <summary>
            /// 经度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lon {
         get; set; }
            /// <summary>
            /// 纬度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lat {
         get; set; }
        }

> 2.摄像头实体：

public class CameraEntity		//摄像头实体
        {
        
    
            public int Id {
         get; set; }
            /// <summary>
            /// 摄像头名称
            /// </summary> 
            public string CameraName {
         get; set; }
            /// <summary>
            /// 所属部门Id
            /// </summary>
            public int? DeptId {
         get; set; }
            public virtual DepartmentEntity dept {
         get; set; }
            /// <summary>
            /// 经度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lng {
         get; set; }
            /// <summary>
            /// 纬度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lat {
         get; set; }
    
        }

> 1.部门 mapping：

public class DepartmentEntityMapping : DataEntityTypeConfiguration<DepartmentEntity>
        {
        
            public DepartmentEntityMapping()
            {
        
             	//部门表
                ToTable("Department");		
                HasKey(t => t.Id);
                //一对多
                HasMany(x => x.lstCamera).WithOptional(z => z.dept).HasForeignKey(y=>y.DeptId);	
            }
        }

> 2.摄像头 mapping：

public class CameraEntityMapping : DataEntityTypeConfiguration<CameraEntity>
        {
        
            public CameraEntityMapping()
            {
        
            	//AssetCameraInfo为数据库表名
                ToTable("AssetCameraInfo");		
                HasKey(t => t.Id);
                //一对多
                HasOptional(x => x.dept).WithMany().HasForeignKey(x => x.DeptId);	
            }
        }

> 1.controller层 – 调用该接口报错 – error：出现循环调用

/// <summary>
            /// 查摄像头集合
            /// </summary>
            /// <param name="model"></param>
            /// <returns></returns>
            [Route("TmpTest")]
            [HttpPost]
            [AllowAnonymous]
            public IHttpActionResult TmpTest([FromBody] QuerCameraInfo model)
            {
        
                TipsModel<List<CameraEntity>> tips = new TipsModel<List<CameraEntity>>(false);
                var lst = new AssetCameraInfoServiceV2().GetList(model);
                tips.SetResult(true, lst, "success");
                return Json(tips);
            }

> 2.Service层

public partial class AssetCameraInfoServiceV2
        {
        
            readonly Repository<CameraEntity> dao = new Repository<CameraEntity>();
     
            private IQueryable<BMS_D_AssetCameraInfoEntity> QueryCmd(QuerCameraInfo where)
            {
        
                var query = dao.Table;
                query = query.Where(x => x.DeleteState == 0);
                if (!where.CameraName.IsEmpty())
                    query = query.Where(x => x.CameraName.Contains(where.CameraName));
                if (!where.DeptId.IsEmpty())
                    query = query.Where(x => x.DeptId == where.DeptId);
                return query;
            }
            
            public List<CameraEntity> GetList(QuerCameraInfo where)
            {
        
                var temp = QueryCmd(where);
                return temp.ToList();
            }
    	}

> 3.model 传参QuerCameraInfo

public class QuerCameraInfo
        {
        
            public int Id {
         get; set; }
            /// <summary>
            /// 摄像头名称
            /// </summary> 
            public string CameraName {
         get; set; }
            /// <summary>
            /// 摄像头编码
            /// </summary>
            public string CameraCode {
         get; set; }
            /// <summary>
            /// 所属部门Id
            /// </summary>
            public int? DeptId {
         get; set; }
            public virtual DepartmentEntity dept {
         get; set; }
        }

--------------------

## 2.报错内容 ##

1.调用 controller层 的接口 TmpTest 报错如下：

"StatusCode": 408,
    "OperateTime": "2022-09-08T14:56:58.9725345+08:00",
    "Message": "2022年9月8日\tSelf referencing loop detected with type 'System.Data.Entity.DynamicProxies.BMS_D_AssetCameraInf_6940526873A10F06EF9B905552C9F9854FEA9BBA8CFBCCDBD1E36BF810A687E9'. Path 'ReturnValue[7].dept.lstCamera'.\t\n"

--------------------

## 3.原因分析： ##

> 通过 GetList() 获得的 lst 集合中，每个相机实体中都有一个部门实体，每个部门中又有相机集合，故而出现死循环。

--------------------

## 4.解决方案： ##

> 将 lst 转换为 model

> 1.controller层 – 分页查询camera

/// <summary>
            /// 查询摄像头信息(分页)
            /// </summary>
            /// <param name="model"></param>
            /// <returns></returns>
            [Route("GetListCameraInfo")]
            [HttpPost]
            [AllowAnonymous]
            public IHttpActionResult GetListCameraInfo([JsonBinder] ElGrid grid)
            {
        
                TipsModel<ElGrid> tips = new TipsModel<ElGrid>(false);
                var where = grid.CreatePageBase<QuerCameraInfo>();
                AssetCameraInfoServiceV2 serveice = new AssetCameraInfoServiceV2();
                //转model
                tips.ReturnValue = grid.SetData(serveice.GetPageList(where), x => x.Select(y => y.ToModel()));
                //转model，model比entity多一个deptName字段
                tips.ReturnValue = grid.SetData(serveice.GetPageList(where), x => x.Select(y => y.ToInfoModel()));
                tips.IsSuccess = true;
                return Json(tips);
            }

--------------------

## 5.补充信息 ##

> 每个 AutoMapper 都对应一个 Profile

> 1.CameraInfoModel

public class CameraInfoModel
        {
        
            public int Id {
         get; set; }
            /// <summary>
            /// 摄像头名称
            /// </summary> 
            public string CameraName {
         get; set; }
            /// <summary>
            /// 所属部门Id
            /// </summary>
            public int? DeptId {
         get; set; }
            /// <summary>
            /// 部门名称
            /// </summary>
            public string DeptName {
         get; set; }
            /// <summary>
            /// 经度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lng {
         get; set; }
            /// <summary>
            /// 纬度
            /// </summary>
            [DecimalPrecision(16, 8)]
            public decimal? Lat {
         get; set; }
       }

> 1.  AutoMapperExcetions 中的 CameraMapper

#region	摄像头信息表 CameraEntity
            public static CameraInfoModel ToInfoModel(this CameraEntity entity)
            {
        
                return entity.MapTo<CameraEntity, CameraInfoModel>();
            }
            public static CameraEntity ToInfoEntity(this CameraInfoModel model)
            {
        
                return model.MapTo<CameraInfoModel, CameraEntity>();
            }
    #endregion

> 3.CameraProfile.cs  
> 将 entity 转换为 CameraInfoModel, 其中根据 deptId 获取部门名称放在 CameraInfoModel 中进行输出.

private void CameraProfile() {
        
                CreateMap<CameraInfoModel, CameraEntity>();
                CreateMap<CameraEntity, CameraInfoModel>()
                    .ForMember(x => x.DeptName, y => y.MapFrom(z => z.dept == null ? "" : z.dept.DeptName));
            }