1

在 RavenDB 中，我了解当您需要计算符合特定条件的属性时，可以实现

  1. 通过针对您希望分组的那些属性名称创建构面，
  2. 然后在上述属性和 where 子句中所需的属性上创建索引。
  3. 最后使用上述索引发出查询。并使用 ToFacets 扩展实现查询。

但是，当您的 where 子句恰好包含一个针对作为文档值集合的属性的谓词时会发生什么？因为如果我将集合中的嵌套属性添加到父文档的索引中，我对父文档属性的构面计数将不准确？

例如

public class Camera { 
  string Make { get;set; }
  string Model { get;set; } 
  double Price { get;set; }
  IEnumerable<string> Showrooms { get;set; }
}

我的查询看起来像

(from camera in session.Query<Camera, Camera_Facets>() 
 where camera.Price < 100 && camera.ShowRooms.Any(s => s.In("VIC", "ACT", "QLD")) 
 select new { 
       camera.Make, 
       camera.Model, 
       camera.Price}
 ).ToFacets("facets/CameraFacets");

更新：这是失败的测试

[TestFixture]
public class FacetedSearchWhenQueryingNestedCollections
{
    public class Car
    {
        public Car()
        {
            Locations = new List<string>();
        }

        public string Id { get; set; }
        public string Make { get; set; }
        public string Model { get; set; }
        public double Price { get; set; }
        public IEnumerable<string> Locations { get; set; }
    }

    public class Car_Facets : AbstractIndexCreationTask<Car>
    {
        public Car_Facets()
        {
            Map = cars => from car in cars
                          select new {car.Make, car.Model, car.Price};
        }
    }

    private static IDocumentSession OpenSession
    {
        get { return new EmbeddableDocumentStore {RunInMemory = true}.Initialize().OpenSession(); }
    }

    [Test]
    public void CanGetFacetsWhenQueryingNesetedCollectionValues()
    {
        var cars = Builder<Car>.CreateListOfSize(50)
            .Section(0, 10)
                .With(x => x.Model = "Camry")
                .With(x => x.Make = "Toyota")
                .With(x => x.Price = 2000)
                .With(x => x.Locations = new[] {"VIC", "ACT"})
            .Section(11, 20)
                .With(x => x.Model = "Corolla")
                .With(x => x.Make = "Toyota")
                .With(x => x.Price = 1000)
                .With(x => x.Locations = new[] { "NSW", "ACT" })
            .Section(21, 30)
                .With(x => x.Model = "Rx8")
                .With(x => x.Make = "Mazda")
                .With(x => x.Price = 5000)
                .With(x => x.Locations = new[] { "ACT", "SA", "TAS" })
            .Section(31, 49)
                .With(x => x.Model = "Civic")
                .With(x => x.Make = "Honda")
                .With(x => x.Price = 1500)
                .With(x => x.Locations = new[] { "QLD", "SA", "TAS" })
            .Build();

        IDictionary<string, IEnumerable<FacetValue>> facets;

        using(var s = OpenSession)
        {
            s.Store(new FacetSetup { Id = "facets/CarFacets", Facets = new List<Facet> { new Facet { Name = "Model" }, new Facet { Name = "Make" }, new Facet { Name = "Price" } } });
            s.SaveChanges();

            IndexCreation.CreateIndexes(typeof(Car_Facets).Assembly, s.Advanced.DocumentStore);

            foreach (var car in cars)
                s.Store(car);

            s.SaveChanges();

            s.Query<Car, Car_Facets>().Customize(x => x.WaitForNonStaleResults()).ToList();

            facets = s.Query<Car, Car_Facets>()
                .Where(x => x.Price < 3000)
                .Where(x => x.Locations.Any(l => l.In("QLD", "VIC")))
                .ToFacets("facets/CarFacets");
        }

        Assert.IsNotNull(facets);
        Assert.IsTrue(facets.All(f => f.Value.Count() > 0));
        Assert.IsTrue(facets.All(f => f.Value.All(x => x.Count > 0)));
    }

    [TearDown]
    public void ClearData()
    {
        using(var s = OpenSession)
        {
            foreach (var car in s.Query<Car>().ToList())
                s.Delete(car);

            s.SaveChanges();
        }
    }
}

但是，如果我将查询更改为。（不再查询嵌套集合）

    facets = s.Query<Car, Car_Facets>()
                .Where(x => x.Price < 3000)
                .ToFacets("facets/CarFacets");

现在我在字典中得到了 3 个枚举，都带有值。

4

1 回答 1

2

如果我将索引更改为

    public class Car_Facets : AbstractIndexCreationTask<Car>
    {
        public Car_Facets()
        {
            Map = cars => from car in cars
                          from location in car.Locations
                          select new {car.Make, car.Model, car.Price, Location = location};
        }
    }

为投影创建一个类

    public class CarOnLocation
    {
        public string Make { get; set; }
        public string Model { get; set; }
        public double Price { get; set; }
        public string Location { get; set; }
    }

然后查询为

    facets = s.Query<Car, Car_Facets>().AsProjection<CarOnLocation>()
                .Where(x => x.Price < 3000)
                .Where(x => x.Location.In("QLD", "VIC"))
                .ToFacets("facets/CarFacets");

有用。

于 2011-10-27T23:05:37.050 回答