我是Raven的新手,所以我甚至不确定我是否在这里采取正确的方法。我需要生成一个项目列表,其属性是从单独的文档中提取的...本质上是一个JOIN。在RavenDB Multi Map中遇到麻烦reduce
说我有这些对象:
public class Merchant
{
public string Id {get;set;}
public string MerchantName {get;set;}
}
public class Location
{
public string Id {get;set;}
public string MerchantId {get;set;}
public string City {get;set;}
}
public class Item
{
public string Id {get;set;}
public string MerchantId {get;set;}
public string ItemName {get;set;}
}
,我需要的MapReduce(我想)到MerchantItem
public class MerchantItem
{
public string ItemId {get;set;}
public string MerchantId {get;set;{
public string LocationId {get;set;}
public string ItemName {get;set;}
public string City {get;set;}
public string MerchantName {get;set;}
}
这里是我的(非工作)多地图缩小的列表:
AddMap<Merchant>(merchants => from m in merchants
select new
{
ItemId = (string)null,
MerchantId = m.Id,
LocationId = (string)null,
ItemName = (string)null,
City = (string)null,
MerchantName = m.Name
});
AddMap<Location>(locations => from l in locations
select new
{
ItemId = (string)null,
MerchantId = l.MerchantId,
LocationId = l.Id,
ItemName = (string)null,
City = l.City,
MerchantName = (string)null
});
AddMap<Item>(items=> from i in items
select new
{
ItemId = i.Id,
MerchantId = i.MerchantId,
LocationId = (string)null,
ItemName = i.ItemName,
City = (string)null,
MerchantName = (string)null
});
Reduce = results => from r in results
group result by r.LocationId
into g
select new
{
ItemId = g.Select(x => x.ItemId),
MerchantId = g.Select(x => x.MerchantId),
LocationId = g.Key,
ItemName = g.Select(x => x.ItemName).Where(x => x != null).FirstOrDefault(),
City = g.Select(x => x.City).Where(x => x != null).FirstOrDefault(),
MerchantName = g.Select(x => x.MerchantName).Where(x => x != null).FirstOrDefault()
});
这个想法是我需要一个MerchantItem用于数据库中的每个Item和Location。在SQL中,我们只是在谈论几个连接,但我完全难以理解如何在Raven中实现这一点。
也许使用Raven的Include()功能作为不同的(更好的?)方法?我在回答这个问题时提供了一个例子:http://stackoverflow.com/questions/9500043/query-list-of-sub-documents-with-ravendb – 2012-03-05 04:38:13
哈,这也是我的问题,是的类似的问题。我只是刚才看到你已经回答了。我会给你一个办法。谢谢。 – 2012-03-05 18:05:32
大声笑。我也注意到了。我在那个答案中描述的是Ayende在下面说的:Include()。 – 2012-03-05 18:18:43