Entity Framework Eager Loading Discover How To Load Related Entities
In Eager loading, a query for one type of entity also loads related entities as part of the query.
- Using eager loading, you don't need to execute a separate query for related entities.
- It means that requesting related data be returned along with query results from the database.
- It can be achieved by using the
Includemethod.
In the following example, all the authors with their respective books are retrieved from the database by using eager loading.
using (var context = new BookStore()) { var authors = context.Authors .Include(a => a.Books) .ToList(); }
The authors and their related books will be retrieved in a single query.
SELECT
[Project1].[AuthorId] AS [AuthorId],
[Project1].[Name] AS [Name],
[Project1].[C1] AS [C1],
[Project1].[Id] AS [Id],
[Project1].[Title] AS [Title],
[Project1].[AuthorId1] AS [AuthorId1]
FROM ( SELECT
[Extent1].[AuthorId] AS [AuthorId],
[Extent1].[Name] AS [Name],
[Extent2].[Id] AS [Id],
[Extent2].[Title] AS [Title],
[Extent2].[AuthorId] AS [AuthorId1],
CASE WHEN ([Extent2].[Id] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
FROM [dbo].[Authors] AS [Extent1]
LEFT OUTER JOIN [dbo].[Books] AS [Extent2] ON [Extent1].[AuthorId] = [Extent2].[AuthorId]
) AS [Project1]
ORDER BY [Project1].[AuthorId] ASC, [Project1].[C1] ASC
ZZZ Projects
