# Lesson 28 of Procure-to-Pay: Enterprise Blazor with Clean Architecture

**URL:** <https://forum.radzen.com/t/lesson-28-of-procure-to-pay-enterprise-blazor-with-clean-architecture/21771>\
**Category:** Radzen.Blazor Components\
**Created:** [November 12, 2026, 3:35pm UTC](https://forum.radzen.com/t/lesson-28-of-procure-to-pay-enterprise-blazor-with-clean-architecture/21771 "2026-11-12T15:35:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Benjamin\_Fadina](https://forum.radzen.com/user_avatar/forum.radzen.com/benjamin_fadina/32/3784_2.png) [@Benjamin\_Fadina](https://forum.radzen.com/u/Benjamin_Fadina)\
**Post date:** [November 12, 2026, 3:35pm UTC](https://forum.radzen.com/t/lesson-28-of-procure-to-pay-enterprise-blazor-with-clean-architecture/21771/1 "2026-11-12T15:35:38Z")

</div>

[![](https://img.youtube.com/vi/5ttWB5pG8R8/maxresdefault.jpg "Blazor P2P #28 — The Purchase Order Aggregate: Creating One From a Requisition") ](https://www.youtube.com/watch?v=5ttWB5pG8R8)

Lesson 28 of Procure-to-Pay: Enterprise Blazor with Clean Architecture.

Covers §5.4 — The Domain Layer.

Chapters  
0:00 The Root, and the One Nullable Foreign Key  
0:36 References by Id, Not by Object  
1:22 Totals Fold, and IsReceivable Names a Rule  
1:56 CreateFromRequisition Takes Whole Aggregates  
2:34 Three Guards, One Per Aggregate It Was Handed  
3:18 Copying the Lines Across  
3:56 AddLine, for the Draft Case

Built with Visual Studio 2026, .NET 10, C# 14, Blazor Web App (Auto),  
EF Core 10, SQL Server and Radzen Blazor Components.

Get the book — "Procure-to-Pay" by Benjamin Fadina:  
[Procure-to-Pay : Building an Enterprise Blazor Application with Clean Architecture, CQRS, Entity Framework Core and Radzen Blazor Components](https://benjaminsqlsever.gumroad.com/l/febnda)

Source code:  
[GitHub - benjaminsqlserver/P2P · GitHub](https://github.com/benjaminsqlserver/P2P)

Source code:  
[GitHub - benjaminsqlserver/P2P · GitHub](https://github.com/benjaminsqlserver/P2P)

More .NET and Blazor tutorials: [https://www.youtube.com/@benjaminfadina3338](https://www.youtube.com/@benjaminfadina3338)

#Blazor #Radzen #dotnet #CleanArchitecture #CQRS #EFCore #CSharp