Practical Domain Driven Design With EFCore - NDC Sydney 2020

Transcript

1. Practical Domain-Driven Design
   With EF Core
   Hossam Barakat
   Technical Lead at Willow
   @hossambarakat_ | www.hossambarakat.net
   

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2. @hossambarakat_
   What is Domain-Driven Design?
   “Domain-Driven Design is an approach to software development
   that centers the development on programming a domain model that
   has a rich understanding of the processes and rules of a domain. ” --
   Martin Fowler
   

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   What is Domain Model?
   “An object model of the domain that incorporates both behavior and
   data. ” - Martin Fowler
   “A system of abstractions that describes selected aspects of a domain and
   can be used to solve problems related to that domain. ” -- Eric Evans
   

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   Strategic Design
   

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   Bounded Contexts
   • A defined part of software where particular terms, definitions and
   rules apply in a consistent way
   • Clear boundaries between different parts of the system
   https://martinfowler.com/bliki/BoundedContext.html
   

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   Focus on the Core Domain
   

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   Inside the Core Domain
   

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   How to apply DDD to my legacy
   codebase?
   

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   Sample Domain
   

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    Sample Domain
    

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    Domain Model
    

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    Demo
    

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    Extract Methods
    

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    Avoid Public Setters
    

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    Encapsulate Behavior in Domain Model
    

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    Encapsulate Collection
    

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    Encapsulate Behavior in Domain Model
    

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    Encapsulate Behavior in Domain Service
    

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    Double Dispatch
    

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    Domain Events
    Entity
    Domain Events
    DBContext
    SaveChanges()
    Event Handler
    Handle()
    Event Handler
    Handle()
    Event Handler
    Handle()
    Mediator
    Publish()
    Action()
    SaveChangesInterceptor
    SavingChanges()
    

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    From Primitive Obsession to Value Objects
    

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    Where is the Repository?
    

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    Can the Unit of Work help us?
    

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    Embrace the DbContext
    

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    What about custom queries?
    • Query classes
    • Specification pattern
    • Extension Methods
    

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    Base Entity ID
    

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27. @hossambarakat_
    Questions
    

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28. @hossambarakat_
    Thanks
    Hossam Barakat
    Tech Lead at Willow
    @HossamBarakat_
    

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