NHibernate 更改审计和组件

Question

我们架构的一个组成部分，因为我们的系统必须为用户提供一个仪表板，以明确地将数据更改从一个环境发布到另一个环境。我们研究了 NH Evers，但我们需要将许多领域特定的东西融入架构中。我们已经成功地使用 NHibernate 的事件模型来跟踪和记录系统中的状态更改(到另一个表)，但最近偶然发现了组件的问题。当 IPostInsertEventListener 和 IPostUpdateEventListener 被触发时，它发布一个值数组，表示实体的当前状态。在更新的情况下，它也会发布一个表示先前状态的数组。我们正在使用这些数组将“之前”和“之后”状态保存到我们的表中。当属性是组件时，实际值(区域中的项目)是组件实例本身 - 即无类型的复杂对象。如果没有交叉引用元模型映射器并对其进行反射(reflection)以提取单个值，我如何才能获得构成组件的实际值？我能够获取映射到组件成员的列名称，但不能获取前后值。

我一直在挖掘 NH 源，但我没有找到如何提取这些值，但显然 NH 知道如何在内部执行此操作，因为它能够正确发布 sql。这是我目前拥有的代码的修改/详细版本，它突出了这个问题:

        public static RowChangedReport Load(IChangeTrackable trackable, object entityId, AbstractEntityPersister persister, object[] state, object[] oldState)
    {
        var report = new RowChangedReport
            {
                Entity = trackable,
                EntityTypeFullName = persister.EntityName,
                TableName = new TableName(persister.GetTableName()),
                EntityId = entityId,
            };

        var authContext = AuthenticationContext.Current;

        if (authContext != null)
            report.SecurityContextUserId = authContext.UserId;

        if (persister.PropertyNames != null && state != null)
        {
            report.ChangedType = oldState == null ? RowChangedTypes.New : RowChangedTypes.Modified;

            for (var index = 0; index < persister.PropertyNames.Length; index++)
            {
                var propertyName = persister.PropertyNames[index];

                IType propertyType = persister.PropertyTypes[index];

                if (!propertyType.IsCollectionType)
                {
                    AddColumnChangeReport(persister, state, oldState, index, propertyName, report);
                }
            }
        }

        report.FinalizeState();

        return report;
    }

    private static void AddColumnChangeReport(AbstractEntityPersister persister, object[] state, object[] oldState, int index, string propertyName, RowChangedReport report)
    {
        var currentValue = state[index];

        // for simple properties, this is always a single element array
        // for components, this is an array with an element for each member on the component - i.e. how the component is mapped
        string[] columns = persister.GetPropertyColumnNames(propertyName);

        var previousValue = oldState == null ? null : oldState[index];

        if (!Equals(currentValue, previousValue))
        {
            if (report.ChangedType == RowChangedTypes.Modified && propertyName == IsActivePropertyName)
                report.FlagAsDeleted();

            foreach (var column in columns)
            {
                // if this is a component, both the currentValue and the previousValue are complex objects
                // need to have a way to get the actual member value per column!
                report.AddChange(new ColumnChangedReport(report, propertyName, column, previousValue, currentValue));
            }
        }
    }

Answer 1

好的，在阅读 NH 代码几个小时后，我偶然发现了 Tuplizers 并将它们追溯到属性 Type。所以解决方案非常简单 - 对于组件，您需要检测它们，转换为 ComponentType 类型，然后向 ComponentType 询问属性值。这里有一些对我有用的代码:

        public static RowChangedReport Load(IChangeTrackable trackable, object entityId, AbstractEntityPersister persister, object[] state, object[] oldState)
    {
        var report = new RowChangedReport
            {
                Entity = trackable,
                EntityTypeFullName = persister.EntityName,
                TableName = new TableName(persister.GetTableName()),
                EntityId = entityId,
            };

        var authContext = AuthenticationContext.Current;

        if (authContext != null)
            report.SecurityContextUserId = authContext.UserId;

        if (persister.PropertyNames != null && state != null)
        {
            report.ChangedType = oldState == null ? RowChangedTypes.New : RowChangedTypes.Modified;

            for (var index = 0; index < persister.PropertyNames.Length; index++)
            {
                var propertyName = persister.PropertyNames[index];

                IType propertyType = persister.PropertyTypes[index];

                if (!propertyType.IsCollectionType)
                {
                    AddColumnChangeReport(persister, state, oldState, index, propertyName, propertyType, report);
                }
            }
        }

        report.FinalizeState();

        return report;
    }

    private static void AddColumnChangeReport(AbstractEntityPersister persister, object[] state, object[] oldState, int index, string propertyName, IType propertyType, RowChangedReport report)
    {
        var currentValue = state[index];

        string[] columns = persister.GetPropertyColumnNames(propertyName);

        var previousValue = oldState == null ? null : oldState[index];

        if (!Equals(currentValue, previousValue))
        {
            if (report.ChangedType == RowChangedTypes.Modified && propertyName == IsActivePropertyName)
                report.FlagAsDeleted();

            if (propertyType.IsComponentType)
            {
                ComponentType component = (ComponentType)propertyType;

                object[] componentCurrentValues = null;

                if (currentValue != null)
                    componentCurrentValues = component.GetPropertyValues(currentValue, EntityMode.Poco);

                object[] componentPreviousValues = null;

                if (currentValue != null)
                    componentPreviousValues = component.GetPropertyValues(previousValue, EntityMode.Poco);

                if ((componentCurrentValues != null && componentCurrentValues.Length != columns.Length) ||
                    (componentPreviousValues != null && componentPreviousValues.Length != columns.Length))
                    throw new ConventionViolationException(GetComponentArraysExceptionMessage(persister, propertyName, columns, componentPreviousValues, componentCurrentValues));

                for (int i = 0; i < columns.Length; i++)
                {
                    var column = columns[i];
                    var componentPreviousValue = componentPreviousValues == null ? null : componentPreviousValues[i];
                    var componentCurrnetValue = componentCurrentValues == null ? null : componentCurrentValues[i];

                    report.AddChange(new ColumnChangedReport(report, propertyName, column, componentPreviousValue, componentCurrnetValue));
                }
            }
            else
            {
                if (columns.Length > 1)
                    throw new ConventionViolationException("Expected only component properties to have multiple columns.  Property '{0}' on entity {1} is violating that assumption.".FormatWith(propertyName, persister.EntityName));

                report.AddChange(new ColumnChangedReport(report, propertyName, columns[0], previousValue, currentValue));
            }
        }
    }