我们有3个模型类:
主持人有很多TournamentBatch。
TournamentBatch具有许多TournamentBatchItem。在TournamentBatch表中将有FK主机。
我们确实对ApplicationDbContext中的SaveChangesAsync进行了覆盖，以允许进行软删除，如下所示:
public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default(CancellationToken))
{
OnBeforeSaving();
return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
}
private void OnBeforeSaving()
{
if (_httpContextAccessor.HttpContext != null)
{
var userName = _httpContextAccessor.HttpContext.User.Identity.Name;
var userId = _httpContextAccessor.HttpContext.User.FindFirstValue(ClaimTypes.NameIdentifier);
// Added
var added = ChangeTracker.Entries().Where(v => v.State == EntityState.Added && typeof(IBaseEntity).IsAssignableFrom(v.Entity.GetType())).ToList();
added.ForEach(entry =>
{
((IBaseEntity)entry.Entity).DateCreated = DateTime.UtcNow;
((IBaseEntity)entry.Entity).CreatedBy = userId;
((IBaseEntity)entry.Entity).LastDateModified = DateTime.UtcNow;
((IBaseEntity)entry.Entity).LastModifiedBy = userId;
});
// Modified
var modified = ChangeTracker.Entries().Where(v => v.State == EntityState.Modified &&
typeof(IBaseEntity).IsAssignableFrom(v.Entity.GetType())).ToList();
modified.ForEach(entry =>
{
((IBaseEntity)entry.Entity).LastDateModified = DateTime.UtcNow;
((IBaseEntity)entry.Entity).LastModifiedBy = userId;
});
// Deleted
var deleted = ChangeTracker.Entries().Where(v => v.State == EntityState.Deleted &&
typeof(IBaseEntity).IsAssignableFrom(v.Entity.GetType())).ToList();
// var deleted = ChangeTracker.Entries().Where(v => v.State == EntityState.Deleted).ToList();
deleted.ForEach(entry =>
{
((IBaseEntity)entry.Entity).DateDeleted = DateTime.UtcNow;
((IBaseEntity)entry.Entity).DeletedBy = userId;
});
foreach (var entry in ChangeTracker.Entries()
.Where(e => e.State == EntityState.Deleted &&
e.Metadata.GetProperties().Any(x => x.Name == "IsDeleted")))
{
switch (entry.State)
{
case EntityState.Added:
entry.CurrentValues["IsDeleted"] = false;
break;
case EntityState.Deleted:
entry.State = EntityState.Modified;
entry.CurrentValues["IsDeleted"] = true;
break;
}
}
}
else
{
// DbInitializer kicks in
}
}
在我们的模型中:
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;
namespace AthlosifyWebArchery.Models
{
public class TournamentBatch : IBaseEntity
{
[Key]
public Guid TournamentBatchID { get; set; }
public Guid HostID { get; set; }
public string Name { get; set; }
public string BatchFilePath { get; set; }
[Display(Name = "Batch File Size (bytes)")]
[DisplayFormat(DataFormatString = "{0:N1}")]
public long BatchFileSize { get; set; }
[Display(Name = "Uploaded (UTC)")]
[DisplayFormat(DataFormatString = "{0:F}")]
public DateTime DateUploaded { get; set; }
public DateTime DateCreated { get; set; }
public string CreatedBy { get; set; }
public DateTime LastDateModified { get; set; }
public string LastModifiedBy { get; set; }
public DateTime? DateDeleted { get; set; }
public string DeletedBy { get; set; }
public bool IsDeleted { get; set; }
public Host Host { get; set; }
public ICollection<TournamentBatchItem> TournamentBatchItems { get; set; }
[Timestamp]
public byte[] RowVersion { get; set; }
[ForeignKey("CreatedBy")]
public ApplicationUser ApplicationCreatedUser { get; set; }
[ForeignKey("LastModifiedBy")]
public ApplicationUser ApplicationLastModifiedUser { get; set; }
}
}
在我们的Razorpage中，我们有一个页面通过执行以下操作删除TournamentBatch，包括TournamentBatchItem:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;
using AthlosifyWebArchery.Data;
using AthlosifyWebArchery.Models;
using Microsoft.Extensions.Logging;
namespace AthlosifyWebArchery.Pages.Administrators.TournamentBatches
{
public class DeleteModel : PageModel
{
private readonly AthlosifyWebArchery.Data.ApplicationDbContext _context;
private readonly ILogger _logger;
public DeleteModel(AthlosifyWebArchery.Data.ApplicationDbContext context,
ILogger<DeleteModel> logger)
{
_context = context;
_logger = logger;
}
[BindProperty]
public TournamentBatch TournamentBatch { get; set; }
public IList<TournamentBatchItem> tournamentBatchItems { get; set; }
public string ConcurrencyErrorMessage { get; set; }
public async Task<IActionResult> OnGetAsync(Guid? id, bool? concurrencyError)
{
if (id == null)
{
return NotFound();
}
TournamentBatch = await _context.TournamentBatch
.AsNoTracking() //Addded
.FirstOrDefaultAsync(m => m.TournamentBatchID == id);
if (TournamentBatch == null)
{
return NotFound();
}
if (concurrencyError.GetValueOrDefault())
{
ConcurrencyErrorMessage = "The record you attempted to delete "
+ "was modified by another user after you selected delete. "
+ "The delete operation was canceled and the current values in the "
+ "database have been displayed. If you still want to delete this "
+ "record, click the Delete button again.";
}
return Page();
}
public async Task<IActionResult> OnPostAsync(Guid? id)
{
try
{
//var tournamentBatchItems = await _context.TournamentBatchItem.Where(m => m.TournamentBatchID == id).ToListAsync();
//_context.TournamentBatchItem.RemoveRange(tournamentBatchItems);
//await _context.SaveChangesAsync();
if (await _context.TournamentBatch.AnyAsync(
m => m.TournamentBatchID == id))
{
// Department.rowVersion value is from when the entity
// was fetched. If it doesn't match the DB, a
// DbUpdateConcurrencyException exception is thrown.
_context.TournamentBatch.Remove(TournamentBatch);
_logger.LogInformation($"TournamentBatch.BeforeSaveChangesAsync ... ");
await _context.SaveChangesAsync();
_logger.LogInformation($"DbInitializer.AfterSaveChangesAsync ... ");
}
return RedirectToPage("./Index");
}
catch(DbUpdateException)
{
return RedirectToPage("./Delete",
new { concurrencyError = true, id = id });
}
//catch (DbUpdateConcurrencyException)
//{
// return RedirectToPage("./Delete",
// new { concurrencyError = true, id = id });
//}
}
}
}
...，并且出现以下错误，这有点奇怪。
有任何想法吗？
我们所做的事情:
OnBeforeSaving();方法中删除了SaveChangesAsyc()，则该代码是删除(硬删除)成功的TournamentBatch和TournamentBatchItem。 OnBeforeSaving();方法中包括了SaveChangesAsyc()并通过删除主机和 TournamentBatchItem (不是 TournamentBatch )进行了测试，则该代码已被成功删除(软删除)。 似乎与Host和TournamentBatch之间的关系有关
环境:
最佳答案
原因
我想原因是您从客户端绑定(bind)了TournamentBatch。
让我们回顾OnPostAsync()方法:
public async Task<IActionResult> OnPostAsync(Guid? id)
{
try
{
if (await _context.TournamentBatch.AnyAsync(
m => m.TournamentBatchID == id))
{
_context.TournamentBatch.Remove(TournamentBatch);
_logger.LogInformation($"TournamentBatch.BeforeSaveChangesAsync ... ");
await _context.SaveChangesAsync();
_logger.LogInformation($"DbInitializer.AfterSaveChangesAsync ... ");
}
return RedirectToPage("./Index");
}
// ....
}
在这里，
TournamentBatch是PageModel 的属性: [BindProperty]
public Models.TournamentBatch TournamentBatch{ get; set; }
请注意，您没有根据ID 从数据库中检索它，而只是，可以通过
_context.TournamentBatch.Remove(TournamentBatch);直接将其删除。换句话说，
TournamentBatch的其他属性将由ModelBinding设置。假设如果您仅提交ID，则所有其他属性均为默认值。例如，Host将为null，并且HostID将为默认的00000000-0000-0000-0000-000000000000。因此，当您保存更改时，EF Core将更新模型，如下所示:UPDATE [TournamentBatch]
SET [HostID] = '00000000-0000-0000-0000-000000000000' ,
[IsDeleted] = 1 ,
# ... other fields
WHERE [TournamentBatchID] = 'A6F5002A-60CA-4B45-D343-08D660167B06'
因为没有ID为
00000000-0000-0000-0000-000000000000的Host记录，所以数据库将提示:如何修复
代替从客户端绑定(bind)
TournamentBatch，您需要通过TournamentBatch从服务器检索TournamentBatch = await _context.TournamentBatch.FindAsync(id);。因此，您将正确设置所有属性，以便EF可以正确更新字段: try
{
//var tournamentBatchItems = await _context.TournamentBatchItem.Where(m => m.TournamentBatchID == id).ToListAsync();
//_context.TournamentBatchItem.RemoveRange(tournamentBatchItems);
//await _context.SaveChangesAsync();
TournamentBatch = await _context.TournamentBatch.FindAsync(id);
if (TournamentBatch != null)
{
// Department.rowVersion value is from when the entity
// was fetched. If it doesn't match the DB, a
// DbUpdateConcurrencyException exception is thrown.
_context.TournamentBatch.Remove(TournamentBatch);
_logger.LogInformation($"TournamentBatch.BeforeSaveChangesAsync ... ");
await _context.SaveChangesAsync();
_logger.LogInformation($"DbInitializer.AfterSaveChangesAsync ... ");
}
return RedirectToPage("./Index");
}
// ...