我有两种不同的对象类型存储在RavenDb中,它们是父/子类型关系,在
JSON中是这样的：
Account/1
{
"Name": "Acc1",}
Items/1
{
"Account": "Account/1","Value" : "100","Tags": [
"tag1","tag2"]
}
Items/2
{
"Account": "Account/1","Value" : "50","Tags": [
"tag2"]
}
请注意,我不想将它们存储在同一文档中,因为一个帐户可能有数千个项目.
我正在尝试编写一个map / reduce索引,它会返回类似于：
{
"Account": "Acc1","TagInfo": [
{ "TagName" : "tag1","Count" : "1",//Count of all the "tag1" occurrences for acc1
"Value" : "100" //Sum of all the Values for acc1 which are tagged 'tag1'
},{ "TagName" : "tag2","Count" : "2",//Two items are tagged "tag2"
"Value" : "150"
}]
}
我想我需要使用多地图将Account和Items集合映射到一起,但我无法找出reduce部分来创建结果的“TagInfo”部分.
这是可能的,还是我在Raven模拟这个错误？
编辑：
我想从这个查询中检索的类看起来像这样：
public class QueryResult
{
public string AccountId {get;set;}
public TagInfo Tags {get;set;}
}
public class TagInfo
{
public string TagName {get;set;}
public int Count {get;set;}
public int TotalSum {get;set;}
}
解决方法
您不能使用Multi Map / Reduce索引,因为您需要在标签上放置一个地图而在帐户上放置另一个地图.他们没有共同的属性,所以你不能在这里有多个地图/减少.
但是,您可以使用TransformResult.这是怎么做的：
public class Account
{
public string Id { get; set; }
public string Name { get; set; }
}
public class Item
{
public string Id { get; set; }
public string AccountId { get; set; }
public int Value { get; set; }
public List<string> Tags { get; set; }
}
public class TagsWithCountAndValues : AbstractIndexCreationTask<Item,TagsWithCountAndValues.ReduceResult>
{
public class ReduceResult
{
public string AccountId { get; set; }
public string AccountName { get; set; }
public string Tag { get; set; }
public int Count { get; set; }
public int TotalSum { get; set; }
}
public TagsWithCountAndValues()
{
Map = items => from item in items
from tag in item.Tags
select new
{
AccountId = item.AccountId,Tag = tag,Count = 1,TotalSum = item.Value
};
Reduce = results => from result in results
group result by result.Tag
into g
select new
{
AccountId = g.Select(x => x.AccountId).FirstOrDefault(),Tag = g.Key,Count = g.Sum(x => x.Count),TotalSum = g.Sum(x => x.TotalSum)
};
TransformResults = (database,results) => from result in results
let account = database.Load<Account>(result.AccountId)
select new
{
AccountId = result.AccountId,AccountName = account.Name,Tag = result.Tag,Count = result.Count,TotalSum = result.TotalSum
};
}
}
之后,您可以像这样查询：
var results = session.Query<TagsWithCountAndValues.ReduceResult,TagsWithCountAndValues>()
.Where(x => x.AccountId == "accounts/1")
.ToList();
