Question

我在我的NHibernate项目中实现了Lucene FT引擎。我要做的其中一件事是支持定期维护，即清理FT索引并从持久化实体重建。我构建了一个通用静态方法PopulateIndex<T>，它可以派生实体类型，查找全文索引列的属性属性，并将它们存储到Lucene目录中。我现在的问题是如何从NHibernate方面为方法提供强类型IEnumerable<T>。

public static void PopulateIndex<T>(IEnumerable<T> entities) where T : class
{
    var entityType = typeof(T);
    if (!IsIndexable(entityType)) return;

    var entityName = entityType.Name;           
    var entityIdName = string.Format("{0}Id", entityName);

    var indexables = GetIndexableProperties(entityType);

    Logger.Info(i => i("Populating the Full-text index with values from the {0} entity...", entityName));
    using (var analyzer = new StandardAnalyzer(Lucene.Net.Util.Version.LUCENE_30))
    using (var writer = new IndexWriter(FullTextDirectory.FullSearchDirectory, analyzer, IndexWriter.MaxFieldLength.UNLIMITED))
    {
        foreach (var entity in entities)
        {
            var entityIdValue = entityType.GetProperty(entityIdName).GetValue(entity).ToString();
            var doc = CreateDocument(entity, entityIdName, entityIdValue, indexables);
            writer.AddDocument(doc);
        }
    }
    Logger.Info(i => i("Index population of {0} is complete.", entityName));
}

这是给我agita的方法：

public void RebuildIndices()
{
    Logger.Info(i => i("Rebuilding the Full-Text indices..."));
    var entityTypes = GetIndexableTypes();

    if (entityTypes.Count() == 0) return;
    FullText.ClearIndices();
    foreach (var entityType in entityTypes)
    {
        FullText.PopulateIndex(
            _Session.CreateCriteria(entityType)
            .List()
            );
    }
}

这似乎会返回强类型List<T>，但事实并非如此。我如何获得强类型列表，或者是否有其他/更好的方法来执行此操作？

Answer 1

如果要获得强类型列表，则应指定泛型参数。我可以建议两种选择：避免反思。我的意思是直接为每种类型调用PopulateIndex：

public void RebuildIndexes()
{
    Logger.Info(i => i("Rebuilding the Full-Text indices..."));
    FullText.ClearIndices();
    FullText.PopulateIndex(LoadEntities<EntityA>());
    FullText.PopulateIndex(LoadEntities<EntityB>());
    ...
}

private IEnumerable<T> LoadEntities<T>()
{
    _Session.QueryOver<T>().List();
}

或者您可以使用反射调用PopulateIndex：

public void RebuildIndices()
{
    Logger.Info(i => i("Rebuilding the Full-Text indices..."));
    var entityTypes = GetIndexableTypes();

    if (entityTypes.Count() == 0) return;
    FullText.ClearIndices();
    foreach (var entityType in entityTypes)
    {
        var entityList = _Session.CreateCriteria(entityType).List();
        var populateIndexMethod = typeof(FullText).GetMethod("PopulateIndex", BindingFlags.Public | BindingFlags.Static);
        var typedPopulateIndexMethod = populateIndexMethod.MakeGenericMethod(entityType);
        typedPopulateIndexMethod.Invoke(null, new object[] { entityList });
    }
}

NHibernate基于Reflection.Type返回强类型的IEnumerable

1 个答案: