如何使用实体框架更新自引用图？
如何使用实体框架更新自引用图？
提问于 2017-12-03 08:23:37
我使用实体框架来处理数据库，并且我有如下自引用模型：
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; }
}我使用GraphDiff库来更新断开连接的图，但它似乎不支持更新自引用图。
我的问题是:使用实体框架更新自引用图的最佳方法是：
- 删除/更新现有physicalObjects
- 插入不存在的physicalObjects
回答 1
Stack Overflow用户
发布于 2018-02-22 08:20:05
假设我有两个实体如下：
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; }
}注意，PhysicalObject是自引用表。
不让我们使用实体框架更新图表：
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方法将递归地更新PhysicalObjects的每一棵树，它看起来如下：
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);
}
}我希望我的代码能帮助其他人知道如何更新自引用表的图形树。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/47616604
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