RavenDB MultiMap索引

Question

我是RavenDB的新手。我正在尝试使用多地图索引功能，尽管我不确定这是否是解决我的问题的最佳方法。所以我有三个文档:单位，汽车，人。

汽车文档看起来像这样：

{
 Id: "cars/123",
 PersonId: "people/1235",
 UnitId: "units/4321",
 Make: "Toyota",
 Model: "Prius"
}

People文档如下所示：

{
   Id: "people/1235",
   FirstName: "test",
   LastName: "test"
}

和单元文档：

{
   Id: "units/4321",
   Address: "blah blah"
}

这是一个简短的例子，在我的真实应用程序中有更多的字段，所以数据反规范化将是我最后的手段。

我需要创建和索引，将所有这三个文档连接到一个文档中。如下所示：

{
   CarId: "cars/123",
   PersonId: "people/1235",
   UnitId: "units/4321",
   Make: "Toyota",
   Model: "Prius"
   FirstName: "test",
   LastName: "test"
   Address: "blah blah"
}

// same unit different person owns a different car

{
   CarId: "cars/122",
   PersonId: "people/1236",
   UnitId: "units/4321",
   Make: "Toyota",
   Model: "4runner"
   FirstName: "test",
   LastName: "test"
   Address: "blah blah"
}

在关系数据库中，我只使用两个连接到通过In的People和Unit表，而我的car表将是一个聚合实体。

下面是我的索引定义：

 public class MyMultiIndex : AbstractMultiMapIndexCreationTask<JoinedDocument>
 {
    public MyMultiIndex()
    {
        // creating maps
        AddMap<Car>(cars => cars.Select(e => new { e.CarId, e.Make, e.Model, PersonId = e.PersonId, UnitId = e.UnitId, FirstName = (null)string, LastName = (null)string, Address = (nul)string }));
        AddMap<People>(people => people.Select(e => new { CarId = (string)null, Make = (string)null, Model = (string)null, PersonId = e.Id, UnitId = (null)string, FirstName = e.FirstName, LastName = e.LastName, Address = (nul)string }));
        AddMap<Unit>(people => people.Select(e => new { CarId = (string)null, Make = (string)null, Model = (string)null, PersonId = (null)string, UnitId = e.null, FirstName = (nul)string , LastName = (nul)string , Address = e.Address }));

        Reduce = results => from result in results
                            group result by result.CarId
                            into g
                            select new JoinedDocument
                            {
                                CarId = g.Key,
                                PersonId = g.First(e => e.CarId == g.Key).PersonId,
                                UnitId = g.First(e => e.CarId == g.Key).UnitId,
                                Model = g.First(e => e.CarId == g.Key).Model,
                                Make = g.First(e => e.CarId == g.Key).Make,

                                **// this never works. It is like result set does not contain anything with this personId. It looks like AddMap for people document did not work.**

                                FirstName = results.First(e => e.PersonId == g.First(ie => ie.CarId == g.Key).PersonId).FirstName,

                                **// this never works. It is like result set does not contain anything with this personId. It looks like AddMap for people document did not work.**

                                LastName = results.First(e => e.PersonId == g.First(ie => ie.CarId == g.Key).PersonId).LastName,

                                **// this never works. It is like result set does not contain anything with this personId. It looks like AddMap for unit document did not work.**

                                UnitAddress = results.First(e => e.UnitId == g.First(ie => ie.CarId == g.Key).UnitId).LastName,
                           };
        Index(map => map.Model, FieldIndexing.Analyzed);
        Index(map => map.Make, FieldIndexing.Analyzed);
        Index(map => map.LastName, FieldIndexing.Analyzed);
        Index(map => map.FirstName, FieldIndexing.Analyzed);
        Index(map => map.Make, FieldIndexing.Analyzed);
        Index(map => map.UnitAddress, FieldIndexing.Analyzed);
    }
 }

当RavenDb运行这个索引时，当它试图运行我提供的Reduce函数时，我看到了错误。当我试图匹配一个存在名字和姓氏的记录时，它抛出了错误，同样的情况也发生在单元上。

Answer 1

看起来您正在尝试将文档数据库与具有关系的对象模型相匹配。这个博客可能会对你有所帮助：

Keeping a Domain Model Pure with RavenDB

请记住，这不是RavenDB的推荐用法，但有时它是必要的，这是处理它的好方法。

Answer 2

你能拥有一辆没有车主的车吗？或者一个没有居民的地址？如果在这两种情况下都是假的，我会将汽车和单元建模为嵌入到一个人的体内。因此person成为您的聚合根，要到达一辆汽车或一个单元，您必须通过person。