c# - ChangeTracker.Entries() CurrentValue 等于 EF7 中的 OriginalValue

Question

我在 EF7/asp.Net Core 应用程序中遇到问题。在我的上下文中，我创建了一个保存方法:

    public int Save()
    {
        ChangeTracker.DetectChanges();
        var modifiedEntities = ChangeTracker.Entries()
            .Where(p => p.State == EntityState.Modified || p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified || p.State == EntityState.Detached).ToList();
        var now = DateTime.UtcNow;

        foreach (var change in modifiedEntities)
        {
            var entityName = change.Entity.GetType().Name;
            var primaryKeyValue = GetPrimaryKeyValue(change.Entity);
            foreach (var prop in change.Entity.GetType().GetTypeInfo().DeclaredProperties)
            {
                if (!prop.GetGetMethod().IsVirtual)
                {
                    var currentValue = change.Property(prop.Name).CurrentValue;
                    var originalValue = change.Property(prop.Name).OriginalValue;
                    if (originalValue.ToString() != currentValue.ToString())
                    {
                        var changeLoged = new ChangeLog
                        {
                            PropertyName = prop.Name,
                            EntityName = entityName,
                            PrimaryKeyValue = primaryKeyValue,
                            DateChange = now,
                            OldValue = originalValue.ToString(),
                            NewValue = currentValue.ToString(),
                            ChangedBy = "test"
                        };
                        ChangeLog.Add(changeLoged);
                    }
                }
            }
        }
        return base.SaveChanges();
    }

和方法 GetPrimaryKeyValue:

protected virtual int GetPrimaryKeyValue<T>(T entity)
    {
        var test = entity;
        var test2 = test.GetType();
        var keyName = this.Model.FindEntityType(test2).FindPrimaryKey().Properties
            .Select(x => x.Name).Single();
        var result = (int)entity.GetType().GetProperty(keyName).GetValue(entity, null);
        if (result < 0)
            return -1;

        return result;
    }

不幸的是，change.Property(prop.Name).CurrentValue 总是等于 OriginalValue，所以如果originalValue.ToString() != currentValue.ToString()

始终返回 false。

Answer 1

替换:

var originalValue = change.Property(prop.Name).OriginalValue;

到:

var originalValue = change.GetDatabaseValues().GetValue<object>(prop.Name);