26 lines
801 B
Markdown
26 lines
801 B
Markdown
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---
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layout: pattern
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title: Repository
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folder: repository
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categories: pattern_cat
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tags: pattern_tag
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---
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**Intent:** 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:** 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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