问题描述
问题已更新,以反映更多细节和简化的复制案例,因为我在评论的帮助下进行了更深入的挖掘。
我有一个自定义的 ValueGenerator,如下所示:
public class UtcDateTimeGenerator : ValueGenerator<DateTime>
{
public override DateTime Next(EntityEntry entry)
{
// This method never seems to be called
return DateTime.UtcNow;
}
protected override object NextValue(EntityEntry entry)
{
// This one is called.
return DateTime.UtcNow;
}
public override bool GeneratesTemporaryValues => false;
}
我的实体:
public abstract class AggregateRoot<TId>
where TId : IComparable
{
public TId Id { get; set; }
}
public abstract class AuditedAggregateRoot<TId> : AggregateRoot<TId>
where TId : IComparable
{
public DateTime Created { get; internal set; }
public DateTime LastModified { get; internal set; }
}
public class Player : AuditedAggregateRoot<Guid>
{
public string ExternalId { get; internal set; }
public string DisplayName { get; internal set; }
public string Email { get; internal set; }
public DateTime LastLogin { get; internal set; }
/// <summary>
/// Required for Entity Framework Core
/// </summary>
private Player()
{
}
public Player([NotNull]string externalId,[NotNull]string displayName,[NotNull]string email)
{
ExternalId = externalId;
DisplayName = displayName;
Email = email;
}
}
我实体的IEntityTypeConfiguration
:
public abstract class AggregateRootTypeConfiguration<TEntity,TKey> : IEntityTypeConfiguration<TEntity>
where TEntity : AggregateRoot<TKey>
where TKey : IComparable
{
public virtual void Configure(EntityTypeBuilder<TEntity> builder)
{
builder.HasKey(x => x.Id);
builder.Property(x => x.Id)
.HasValueGenerator<SequentialGuidValueGenerator>()
.ValueGeneratedOnAdd()
.IsRequired();
}
}
public class AuditedAggregateRootTypeConfiguration<TEntity,TKey> : AggregateRootTypeConfiguration<TEntity,TKey>
where TEntity : AuditedAggregateRoot<TKey>
where TKey : IComparable
{
public override void Configure(EntityTypeBuilder<TEntity> builder)
{
base.Configure(builder);
builder.Property(x => x.Created)
.HasValueGenerator<UtcDateTimeGenerator>()
.ValueGeneratedOnAdd()
.IsRequired();
builder.Property(x => x.LastModified)
.HasValueGenerator<UtcDateTimeGenerator>()
.ValueGeneratedOnAddOrUpdate()
.IsRequired();
}
}
public class PlayerEntityTypeConfiguration : AuditedAggregateRootTypeConfiguration<Player,Guid>
{
public override void Configure(EntityTypeBuilder<Player> builder)
{
base.Configure(builder);
builder.Property(x => x.Email)
.HasMaxLength(254)
.IsRequired();
builder.Property(x => x.ExternalId)
.HasMaxLength(200)
.IsRequired();
builder.Property(x => x.DisplayName)
.HasMaxLength(200)
.IsRequired();
builder.HasIndex(x => x.ExternalId).IsUnique();
builder.HasIndex(x => x.Email).IsUnique();
builder.HasIndex(x => x.DisplayName).IsUnique();
}
}
数据库上下文:
public class MyDbContext : DbContext
{
public EmpiresDbContext(DbContextOptions<EmpiresDbContext> dbContextOptions) : base(dbContextOptions)
{
}
public DbSet<Player> Players { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.ApplyConfigurationsFromAssembly(typeof(EmpiresDbContext).Assembly);
base.OnModelCreating(modelBuilder);
}
/*
* Overrides below to fix EF Core not calling ValueGenerator's on update
* See: https://github.com/dotnet/efcore/issues/19765#issuecomment-617679987
*/
public override int SaveChanges(bool acceptAllChangesOnSuccess)
{
GenerateOnUpdate();
return base.SaveChanges(acceptAllChangesOnSuccess);
}
public override Task<int> SaveChangesAsync(
bool acceptAllChangesOnSuccess,CancellationToken cancellationToken = default)
{
GenerateOnUpdate();
return base.SaveChangesAsync(acceptAllChangesOnSuccess,cancellationToken);
}
private void GenerateOnUpdate()
{
foreach (var entityEntry in ChangeTracker.Entries())
{
foreach (var propertyEntry in entityEntry.Properties)
{
var property = propertyEntry.Metadata;
var valueGeneratorFactory =
property.GetValueGeneratorFactory();
var generatedOnUpdate = (property.ValueGenerated & ValueGenerated.OnUpdate)
== ValueGenerated.OnUpdate;
if (!generatedOnUpdate || valueGeneratorFactory == null)
{
continue;
}
var valueGenerator = valueGeneratorFactory.Invoke(
property,entityEntry.Metadata);
propertyEntry.CurrentValue = valueGenerator.Next(entityEntry);
}
}
}
}
我将 MyDbContext
注入服务,然后在 CreatePlayer
方法中:
var player = new Player(externalId,displayName,email);
_dbContext.Players.Add(player);
await _dbContext.SaveChangesAsync();
但是,当调用 await _dbContext.SaveChangesAsync();
时,出现异常:
SqlException: 无法将值 NULL 插入到列 'LastModified'
我用断点检查了 Dbcontext 中的 propertyEntry.CurrentValue = valueGenerator.Next(entityEntry);
行是否被命中,并且它正在为 LastModified
属性分配正确的值。
通过 SQL 跟踪,我可以看到生成的 SQL 如下:
exec sp_executesql N'SET NOCOUNT ON;
INSERT INTO [Players] ([Id],[Created],[DisplayName],[Email],[ExternalId],[LastLogin])
VALUES (@p0,@p1,@p2,@p3,@p4,@p5);
SELECT [LastModified]
FROM [Players]
WHERE @@ROWCOUNT = 1 AND [Id] = @p0;
',N'@p0 uniqueidentifier,@p1 datetime2(7),@p2 nvarchar(200),@p3 nvarchar(254),@p4 nvarchar(4000),@p5 datetime2(7)',@p0='C17E4EC8-CDD6-458A-8CEF-08D8C5D6F63A',@p1='2021-01-31 11:00:27.1068666',@p2=N'Kyr',@p3=N'test@test.test',@p4=N'my-iDp-id-removed-for-security',@p5='0001-01-01 00:00:00'
如上所示,LastModified
列甚至没有被引用。
解决方法
你的 ValueGenerator
对我来说效果很好。
要缩小问题的原因,请暂时在服务类中直接依赖您的 DbContext
-
public class PlayerService : IPlayerService
{
private EmpiresDbContext _dbContext;
public PlayerService(EmpiresDbContext context)
{
_dbContext = context;
}
}
看看下面的代码是否有效 -
var player = new Player(externalId,displayName,email);
try
{
_dbContext.Players.Add(player);
await _dbContext.SaveChangesAsync();
}
catch(DbUpdateException ex)
{
var message = ex.Message;
throw;
}
两条建议(与您的问题没有直接关系)-
- 从您的代码中删除所有
.ConfigureAwait(false)
。检查 this answer 以了解原因。 - 不要将事务用于这样的单个插入操作;它会以牺牲性能为代价,没有任何好处。
编辑:
仔细阅读您更新后的帖子中的代码,我发现您正在使用带有 .ValueGeneratedOnAddOrUpdate()
字段的 LastModified
配置,据我所知,此配置存在一个已知问题。您甚至可能会在 EF Core 的 GitHub
存储库上找到有关此内容的问题。
我建议使用 .ValueGeneratedOnAdd()
配置,与 Created
字段一样,然后手动处理更新方案。