Tutorials Entity Framework Core Tutorial
Eager Loading in EF Core
Eager Loading in EF Core: free step-by-step lesson with examples, common mistakes, and interview tips — part of Entity Framework Core Tutorial on Toolliyo Academy.
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Entity Framework Core Tutorial · Lesson 45 of 100
Eager Loading in EF Core
Beginner ✓ → Intermediate ✓ → Advanced → Professional
Advanced · 3 — Production skills · ~6 min · Module 5: Relationships
What is this?
Eager loading fetches related entities upfront using Include and ThenInclude on the initial query — EF generates JOINs or multiple queries with split option.
Why should you care?
ShopNest product detail page needs Category and Tags immediately — one shaped query beats lazy loading surprises.
See it live — copy this example
Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).
var product = await _context.Products
.Include(p => p.Category)
.Include(p => p.Tags)
.Include(p => p.Detail)
.AsSplitQuery()
.FirstOrDefaultAsync(p => p.Id == id);What happened?
- Each Include adds related data to the same query (or split queries).
- AsSplitQuery avoids cartesian explosion from multiple collections.
Practice next
- List required navigations for the UI screen.
- Add Include/ThenInclude before FirstOrDefaultAsync.
- Enable split query when including multiple collections.
- Swap AsSplitQuery off and compare row multiplication in SQL profiler.
- Use filtered include: Include(p => p.Reviews.Where(r => r.IsApproved)).
Remember
Include loads related data eagerly. ThenInclude walks deeper graphs. Split query helps multiple collection Includes.
ShopNest PDP load
Product detail endpoint Includes Category, Tags, Detail in one split query.
Outcome: Page renders without N+1 lazy load latency spikes.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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