Question

我想创建一个基本的嵌套索引，它只包含包含文档的id和嵌套数据。在ravenDb文档之后，我做了如下：

 public class LeaguesIndex : AbstractIndexCreationTask<CommunityDocument>
{
    public class Result
    {
        public string CommunityId { get; set; }
        public Domain.TeamLeague League { get; set; }
    }

    public LeaguesIndex()
    {
         Map = communities => from community in communities
            from league in community.TeamLeagues
            select new
            {
                CommunityId = community.Id.Replace("CommunityDocuments/", string.Empty),
                League = league
            };
    }
}

查询它：

 var leagues = session
                .Query<LeaguesIndex.Result, LeaguesIndex>()
                .Where(x => x.CommunityId == input.Id)
                .OfType<CommunityDocument>()
                .ToList();

这确实产生了结果，但结果包含整个CommunityDocument。我该怎么做才能获得LeaguesIndex.Result类？（我尝试删除'OfType'行，但它不喜欢它。）

编辑 - 这是有效的：

public class LeaguesIndex : AbstractIndexCreationTask<CommunityDocument, LeaguesIndex.Result>
{
    public class Result
    {
        public string CommunityId { get; set; }
        public Domain.League League { get; set; }
    }

    public LeaguesIndex()
    {
         Map = communities => from community in communities
            from league in community.TeamLeagues
            select new
            {
                CommunityId = community.Id.Replace("CommunityDocuments/", string.Empty),
                League = league
            };
        StoreAllFields(FieldStorage.Yes);
    }
}

查询：

var lastLeague = session
            .Query<LeaguesIndex.Result, LeaguesIndex>()
            .Where(x => x.CommunityId == input.Id)
            .AsProjection<LeaguesIndex.Result>()
            .LastOrDefault();

Answer 1

对于RavenDB 3.5，您应该使用ProjectFromIndexFieldsInto：

var lastLeague = session
    .Query<LeaguesIndex.Result, LeaguesIndex>()
    .Where(x => x.CommunityId == id)
    .ProjectFromIndexFieldsInto<LeaguesIndex.Result>()
    .LastOrDefault();

有关详细信息，请参阅https://ravendb.net/docs/article-page/3.5/Csharp/client-api/session/querying/how-to-perform-projection。

请注意链接文档：

投影从服务器请求要下载的字段数组，如果索引包含那些字段（存储它们），它们将直接来自索引，否则将使用来自文档的值。

这意味着除非您将数据存储在索引中，否则数据将从文档中加载，从而降低性能。

假设RavenDB 4.0的旧答案：

使用ProjectInto<T>：

var leagues = session
    .Query<LeaguesIndex.Result, LeaguesIndex>()
    .Where(x => x.CommunityId == input.Id)
    .ProjectInto<LeaguesIndex.Result>()
    .ToList();

有关详细信息，请参阅https://ravendb.net/docs/article-page/4.0/csharp/indexes/querying/projections#projectinto。

基本嵌套索引

1 个答案: