如何使用实体框架更新自引用图？

Z时代
2024-01-10
分类：问答

我使用实体框架来处理数据库，我也自参照模型如下：如何使用实体框架更新自引用图？

public class PhysicalObject 
{ 
    public PhysicalObject() 
    { 
     SubPhysicalObjects = new HashSet<PhysicalObject>(); 
    } 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int Id { get; set; } 
    public int? ParentId { get; set; } 
    [StringLength(150)] 
    public string Title { get; set; } 
    public virtual PhysicalObject Parent { get; set; } 
    public virtual ICollection<PhysicalObject> SubPhysicalObjects { get; set; } 
}

我用GraphDiff库更新断开的绘图，但似乎它不支持自我更新引用图。

我的问题是：什么是更新使用实体框架的自我参照图的最佳方式：

删除/更新现有physicalObjects

插入不存在physicalObjects

回答：

假设我有两个实体，如下所示：

public class PhysicalObject 
{ 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int Id { get; set; } 
    public int? ParentId { get; set; } 
    public int StorageRequestId { get; set; } 
    public string Title { get; set; } 
    public virtual PhysicalObject Parent { get; set; } 
    public virtual ICollection<PhysicalObject> SubPhysicalObjects { get; set; } 
    public virtual StorageRequest StorageRequest { get; set; } 
} 
public class StorageRequest 
{ 
    public StorageRequest() 
    { 
     PhysicalObjects = new HashSet<PhysicalObject>(); 
    } 
    [Key] 
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
    public int Id { get; set; } 
    public string Title { get; set; } 
    public virtual ICollection<PhysicalObject> PhysicalObjects { get; set; } 
}

请注意，PhysicalObject是自引用表。

var oldPhysicalObjects = dbContext.PhysicalObjects.Where(x => x.StorageRequestId== storageRequestId).ToList(); 
var existingIds = new HashSet<int>(); 
foreach (var item in newGraphDto.PhysicalObjects.ToList()) 
    { 
    updateGraph(item, oldPhysicalObjects, dbContext, storageRequestId,existingIds); 
    } 
var posToDelete = oldPhysicalObjects.Where(x => existingIds.All(e => e != x.Id)).ToList(); 
dbContext.PhysicalObjects.RemoveRange(posToDelete); 
dbContext.SaveChanges();

updateGraph方法将更新PhysicalObjects递归的每一棵树，它看起来像：

private void updateGraph(PhysicalObjectDto physicalObjectDto, IList<PhysicalObject> oldPhysicalObjects, MyDbContext dbContext, int storageRequestId, HashSet<int> existingIds, PhysicalObject parent = null) 
    { 
     if (physicalObjectAddEditDto.Id == 0) 
     { 
      PhysicalObject po = new PhysicalObject 
      { 
       Id = physicalObjectAddEditDto.Id, 
       Title = physicalObjectAddEditDto.Title, 
       StorageRequestId = storageRequestId, 
       Parent=parent 
      }; 
      dbContext.PhysicalObjects.Add(po); 
      parent = po; 
     } 
     else 
     { 
      var po = oldPhysicalObjects.FirstOrDefault(x => x.Id == physicalObjectAddEditDto.Id); 
      po.Title = physicalObjectAddEditDto.Title; 
      po.StorageRequestId = storageRequestId; 
      po.Parent = parent; 
      dbContext.Entry(po).CurrentValues.SetValues(po); 
      parent = po; 
     } 
     existingIds.Add(parent.Id); 
     foreach (var subPhysicalObject in physicalObjectAddEditDto.SubPhysicalObjects) 
     { 
      updateGraph(subPhysicalObject, oldPhysicalObjects, dbContext, mailRoomRequestId, existingIds, parent); 
     } 
    }