RavenDB索引与map reduce不同

Question

我有一个稍微复杂的索引，我需要一个RavenDB文档

给出如下文档定义:

public class PriceDocument
{
    public string Id { get; set; }
    public Guid PriceId { get; set; }
    public decimal Price { get; set; }
    public DateTime? PricingDate { get; set; }
    public string Source { get; set; }
    public int Version { get; set; }    
}

我需要获得给定productId的所有产品(我可以在查询时做到这一点)PricingDate(最新)和Source

那么给定以下数据:

var priceDocument = new PriceDocument  {
    Price = 1m,
    Id = productId + "/1",
    PricingDate = new DateTime(2011, 4, 1, 8, 0, 0),
    PriceId = productId,
    Source = "Bloomberg",
    Version = 1   
};
var priceDocument1 = new PriceDocument {
    Price = 1m,
    Id = productId + "/2",
    PricingDate = new DateTime(2011, 4, 1,9,0,0),
    PriceId = productId,
    Source = "Bloomberg", 
    Version = 1
};

我应该得到的结果是priceDocument1，因为它是最新的。

到目前为止，我有一个这样定义的索引:

Map = docs => 
    from priceDocument in docs
    select new {
        PricingDate = priceDocument.PricingDate, 
        PricingSource = priceDocument.Source,
        Price = priceDocument.Price,
        PriceId = priceDocument.PriceId
    };
Reduce = results => 
    from result in results
    group result by new { result.PricingDate, result.Source } into price
    select new {
        PricingDate = price.Max(p => price.Key.PricingDate),
        PricingSource = price.Key.Source,
    };

但它不工作在运行时，我得到一个AbstractIndexingExecuter||8||Failed to index documents for index (my index name)

我在一个单独的项目中重新创建了这个样本，我可以看到，在Raven Studio的统计中，我得到了错误:

不能隐式转换类型'System '。DateTimeOffset' to 'int'将DateTime?改为DateTime

没有运气。

我从使用日期切换到使用我可以依赖它递增，所以现在索引看起来像这样:

Map = docs => 
    from priceDocument in docs
    select new {
        PricingDate = priceDocument.PricingDate,
        PricingSource = priceDocument.Source,
        ProductId = priceDocument.ProductId,
        ProductVersion = priceDocument.Version
    };
Reduce = results => 
    from result in results
    group result by new {
        result.PriceId,
        result.PricingDate,
        result.Source,
        result.Version
    } into price
    select new {
        PricingDate = price.Key.PricingDate,
        PricingSource = price.Key,
        ProductVersion = price.Max(p=> price.Key.Version)
    };

现在没有抛出错误，但是它也没有给出结果。

Answer 1

应该是这样:

   PricingDate = price.Max(p => (DateTimeOffset)price.Key.PricingDate)

但是你想要的并不需要map reduce索引。你可以使用:

session.Query<PriceDocument>()
       .Where(x=>x.ProduceId == prodId)
       .OrderByDescending(x=>x.PriceDate)
       .FirstOrDefault();

你的Map/Reduce索引不起作用的原因是你有不同的Map &减少功能。

Answer 2

尝试从

更改索引的Reduce部分中的这一行

PricingDate = price.Max(p => price.Key.PricingDate)

PricingDate = price.Max(p => (int)price.Key.PricingDate)