39 lines
1.2 KiB
Markdown
39 lines
1.2 KiB
Markdown
---
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layout: pattern
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title: Repository
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folder: repository
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permalink: /patterns/repository/
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pumlid: JSV13OCm30NGLM00udktCS42eyI9xE-YRjyUUtjlLQij3qblomNCU14vF-LKNBbdYDTX44EfevEsV1ZiTFERjqD2Jzic0-8Mr3b-89SvGZ7yGuBwrvBUoypUlW00
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categories: Persistence Tier
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tags:
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- Java
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- Difficulty-Intermediate
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- Spring
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---
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## Intent
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Repository layer is added between the domain and data mapping
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layers to isolate domain objects from details of the database access code and
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to minimize scattering and duplication of query code. The Repository pattern is
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especially useful in systems where number of domain classes is large or heavy
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querying is utilized.
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## Applicability
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Use the Repository pattern when
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* the number of domain objects is large
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* you want to avoid duplication of query code
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* you want to keep the database querying code in single place
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* you have multiple data sources
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## Real world examples
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* [Spring Data](http://projects.spring.io/spring-data/)
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## Credits
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* [Don’t use DAO, use Repository](http://thinkinginobjects.com/2012/08/26/dont-use-dao-use-repository/)
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* [Advanced Spring Data JPA - Specifications and Querydsl](https://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/)
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