Pursuing Domain-Driven Design practices in PHP
Download as PPT, PDF13 likes7,305 views
The document discusses pursuing Domain-Driven Design practices in PHP. It covers building blocks like entities, value objects, aggregates, repositories, factories and services. It also discusses data modeling approaches like moving from active record to data mapper patterns. The document provides examples of implementing these concepts in PHP using annotations and libraries like Doctrine. It aims to help structure applications around the domain model and apply DDD practices like ubiquitous language in PHP projects.
Pursuing Domain-Driven Design practices in PHP
- 1. Pursuing Domain-Driven Design practices in PHP
- 2. Who am I Giorgio Sironi Bachelor in Computer Engineering Advisor @ Allbus Zone Leader @ DZone
- 3. The long title Pursuing Domain-Driven Design practices in PHP
- 4. The DDD box of goods Knowledge crunching Ubiquitous Language Domain Model Refactoring towards deeper insight... Collaboration patterns (Anti-corruption layer, Separate ways, ...)
- 5. Why? (the most important slide) Close to business, to follow its changes aids iterative development The code is the design supported by blackboards and UML Test and develop with in-memory objects no instantiation of Oracle connections It's also fun! exercise creativity and learning skills
- 6. Domain Model Reflects knowledge of the domain more than technology While there is value in the item on the right, we value the item on the left more Persistence-agnostic (UnitOfWork) In general, no outward dependencies
- 7. Step 1: from relational... user id username password active user_group id_user id_group group id name logo
- 8. Step 1: ...to object-oriented class User { } class Group { }
- 9. Step 2: from Active Record... class Group extends Doctrine_Record { } Hard dependency towards ORM Inherits pollution from Doctrine_Record
- 10. Step 2: … to Data Mapper /** * @Entity */ class User { }
- 11. Building blocks Entity Value Object Aggregate Repository Factory Service Other transient objects (Specification, ...)
- 12. Entity More than a row Equality is based on identity e.g. Post #42, user 'giorgiosironi', … The bread and butter of your Domain Model
- 13. Value Object Previously known in the world as value e.g. the number 42, Zip code 22031, #FF0000 Equality based on values Immutable in certain implementations
- 14. Aggregate Subgraph of Entities and Value Objects with a single entry: the root possible multiple exits, mostly to follow during reading Unit of consistency: loose correspondency to database transactions
- 15. Checkpoint: data modeling
- 16. Repository The gate to the database One aggregate at the time The illusion of an in-memory collection of Entities (Fowler's definition)
- 17. Factory Encapsulate creation of complex Aggregates a new() is often all you need
- 18. Service At the domain level Introduced to avoid mutual dependencies, or field references to strange things, in Entities&Value Objects Optimal for isolation from libraries
- 19. Checkpoint: lifecycle classes
- 21. Active Record vs. Data Mapper Doctrine 2 for persistence (see tutorial by @juokaz) By default for Doctrine 2 object === row All the tricks are at http://github.com/giorgiosironi/ddd-talk
- 22. Entity @Entity annotation no extends @Column for fields private fields types are PHP types: string , not varchar
- 23. Value Objects Do you want an (id, date) table? Serialization of the whole object Conversion into a custom string/numerical format via a custom DBAL data type Deconstruction/reconstruction with lifecycle hooks Combined approaches: serialization and mirror fields
- 24. Aggregate Relationships: @OneToMany, @ManyToMany, @OneToOne, … @OneToMany(..., cascade={“persist”, “remove”}) @OneToMany(..., orphanRemoval=true) @ManyToMany(targetEntity="Phonenumber") @JoinTable(..., inverseJoinColumns={name=”phonenumber_id", referencedColumnName="id", unique=true)
- 25. Repository Plain Old PHP Object Composing EntityManager It's possible to define EntityManager custom repositories: quick and dirty Encapsulates queries Typical methods: add($root), remove($root), find($id), findByStrangeCriteria() It's a collection!
- 26. Factory, Service POPO Sometimes composing services or infrastructure objects (e.g. generating new progressive number for invoices, calculate current taxes, sending mails...) Often decoupled with an interface
- 27. References The code shown in this talk http://github.com/giorgiosironi/ddd-talk Four books http://domaindrivendesign.org/books Domain-Driven Design mailing list Google that :)
- 28. Q/A
- 29. Thanks for your attention