Язык программирования C#9 и платформа .NET5 - Троелсен Эндрю

[Fact]

public void ShouldGetCarsOnOrderWithRelatedPropertiesAsSplitQuery()

{

  IQueryable<Car> query = Context.Cars.Where(c => c.Orders.Any())

    .Include(c => c.MakeNavigation)

    .Include(c => c.Orders).ThenInclude(o => o.CustomerNavigation)

    <b>.AsSplitQuery()</b>;

  var cars = query.ToList();

  Assert.Equal(4, cars.Count);

  cars.ForEach(c =&gt;

  {

    Assert.NotNull(c.MakeNavigation);

    Assert.NotNull(c.Orders.ToList()[0].CustomerNavigation);

  });

}

Метод ToQueryString() возвращает только первый запрос, поэтому последующие запросы были получены с применением профилировщика SQL Server:

SELECT [i].[Id], [i].[Color], [i].[IsDrivable], [i].[MakeId],

       [i].[PetName], [i].[TimeStamp], [m].[Id], [m].[Name], [m].[TimeStamp]

FROM [dbo].[Inventory] AS [i]

INNER JOIN [dbo].[Makes] AS [m] ON [i].[MakeId] = [m].[Id]

WHERE ([i].[IsDrivable] = CAST(1 AS bit)) AND EXISTS (

SELECT 1

    FROM [Dbo].[Orders] AS [o]

    INNER JOIN (

      SELECT [i0].[Id], [i0].[Color], [i0].[IsDrivable], [i0].[MakeId],

             [i0].[PetName], [i0].[TimeStamp]

      FROM [dbo].[Inventory] AS [i0]

      WHERE [i0].[IsDrivable] = CAST(1 AS bit)

    ) AS [t] ON [o].[CarId] = [t].[Id]

    WHERE ([t].[IsDrivable] = CAST(1 AS bit)) AND ([i].[Id] = [o].[CarId]))

ORDER BY [i].[Id], [m].[Id]

SELECT [t0].[Id], [t0].[CarId], [t0].[CustomerId], [t0].[TimeStamp],

       [t0].[Id1], [t0].[TimeStamp1], [t0].[FirstName], [t0].[FullName],

       [t0].[LastName], [i].[Id], [m].[Id]

FROM [dbo].[Inventory] AS [i]

INNER JOIN [dbo].[Makes] AS [m] ON [i].[MakeId] = [m].[Id]

INNER JOIN (

  SELECT [o].[Id], [o].[CarId], [o].[CustomerId], [o].[TimeStamp],

         [c].[Id] AS [Id1], [c].[TimeStamp] AS [TimeStamp1], [c].[FirstName],

         [c].[FullName], [c].[LastName]

  FROM [Dbo].[Orders] AS [o]

  INNER JOIN (

    SELECT [i0].[Id], [i0].[IsDrivable]

(window.adrunTag = window.adrunTag || []).push({v: 1, el: 'adrun-4-390', c: 4, b: 390})

    FROM [dbo].[Inventory] AS [i0]

    WHERE [i0].[IsDrivable] = CAST(1 AS bit)

  ) AS [t] ON [o].[CarId] = [t].[Id]

    INNER JOIN [Dbo].[Customers] AS [c] ON [o].[CustomerId] = [c].[Id]

    WHERE [t].[IsDrivable] = CAST(1 AS bit)

) AS [t0] ON [i].[Id] = [t0].[CarId]

WHERE ([i].[IsDrivable] = CAST(1 AS bit)) AND EXISTS (

    SELECT 1

    FROM [Dbo].[Orders] AS [o0]

    INNER JOIN (

      SELECT [i1].[Id], [i1].[Color], [i1].[IsDrivable], [i1].[MakeId],

             [i1].[PetName], [i1].[TimeStamp]

      FROM [dbo].[Inventory] AS [i1]

      WHERE [i1].[IsDrivable] = CAST(1 AS bit)

    ) AS [t1] ON [o0].[CarId] = [t1].[Id]

    WHERE ([t1].[IsDrivable] = CAST(1 AS bit)) AND ([i].[Id] = [o0].[CarId]))

ORDER BY [i].[Id], [m].[Id]

Будете вы разделять свои запросы или нет, зависит от существующих бизнес-требований.

Фильтрация связанных данных

В версии EF Core 5 появилась возможность фильтрации при включении навигационных свойств типа коллекций. До выхода EF Core 5 единственным способом получения отфильтрованного списка для навигационного свойства типа коллекций было использование явной загрузки. Добавьте в MakeTests.cs следующий тест, который демонстрирует получение записей производителей, выпускающих автомобили желтого цвета:

[Fact]

public void ShouldGetAllMakesAndCarsThatAreYellow()

{

  var query = Context.Makes.IgnoreQueryFilters()

<b>      .Include(x =&gt; x.Cars.Where(x =&gt; x.Color == &quot;Yellow&quot;));</b>

     var qs = query.ToQueryString();

  var makes = query.ToList();

  Assert.NotNull(makes);

  Assert.NotEmpty(makes);

  Assert.NotEmpty(makes.Where(x =&gt; x.Cars.Any()));

  Assert.Empty(makes.First(m =&gt; m.Id == 1).Cars);

  Assert.Empty(makes.First(m =&gt; m.Id == 2).Cars);

  Assert.Empty(makes.First(m =&gt; m.Id == 3).Cars);

  Assert.Single(makes.First(m =&gt; m.Id == 4).Cars);

  Assert.Empty(makes.First(m =&gt; m.Id == 5).Cars);

}

Ниже показан сгенерированный код SQL: