EF LINQ query to SQL OUTER APPLY - entity-framework

Question

How to generate such SQL code:
SELECT TOP(10) c.Id AS CarId, r.FranceAccessoriesCount, r.GermanyAccessoriesCount, r.ItalyAccessoriesCount
FROM [Cars] AS c
OUTER APPLY (SELECT
SUM(CASE WHEN a.ManufacturerCountry = 'France' then 1 ELSE 0 END) as FranceAccessoriesCount,
SUM(CASE WHEN a.ManufacturerCountry = 'Germany' then 1 ELSE 0 END) as GermanyAccessoriesCount,
SUM(CASE WHEN a.ManufacturerCountry = 'Italy' then 1 ELSE 0 END) as ItalyAccessoriesCount
FROM [Accessories] a
WHERE a.CarId = c.Id AND a.[Year] > 1999) r
using LINQ query (EF Core)?
I've tried:
await this.context.Cars
.Take(10)
.Select(c => new
{
CarId = c.Id,
Accessories = this.context.Accessories.Where(a => a.CarId == c.Id && a.Year > 1999)
})
.Select(c => new
{
CarId = c.CarId,
FranceAccessoriesCount = c.Accessories.Count(a => a.ManufacturerCountry == "France"),
GermanAccessoriesCount = c.Accessories.Count(a => a.ManufacturerCountry == "Germany"),
ItalyAccessoriesCount = c.Accessories.Count(a => a.ManufacturerCountry == "Italy")
})
.ToListAsync();
But this doesn't generate OUTER APPLY. Instead it translates to:
SELECT TOP(10) [c].[Id] AS CarId (
SELECT COUNT(*)
FROM [Accessories] AS [a]
WHERE (([a].[CarId] = [c].[Id]) AND [a].[Year] > 1999) AND ([a].[ManufacturerCountry ] = N'France')) AS [FranceAccessoriesCount ], (
SELECT COUNT(*)
FROM [Accessories] AS [a1]
WHERE (([a].[CarId] = [c].[Id]) AND [a1].[Year] > 1999) AND ([a1].[ManufacturerCountry ] = N'Germany')) AS [GermanyAccessoriesCount ], (
SELECT COUNT(*)
FROM [Accessories] AS [a2]
WHERE (([a2].[CarId] = [c].[Id]) AND [a2].[Year] > 1999) AND ([a2].[ManufacturerCountry ] = N'Italy')) AS [ItalyAccessoriesCount]
FROM [Cars] AS [c]
How to write LINQ query which will translate in OUTER APPLY?

Answer 1

EF is a mapper. You tell it what you want using entities as you have them defined and it generates an SQL statement to retrieve and project that data. It may not be optimal in all circumstances but generally it is quite good from a performance perspective.
If the EF query is not returning the data you expect to see, then approach it from the desired data you want to project to and express a question from what projection you want vs. what projection you get.
If the EF query is returning the data you expect, but simply isn't using a CROSS APPLY like you expect, then the answer is that if this is important, don't rely on the EF generated query and instead have it execute a hand-crafted SQL statement.