[Nest.js] 7- Entity & Repository

Contents
Entity?
Repository?

 

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Entity

- Entity is a class that maps to a database table, so it is very closed to database model.

- @Entity() decorator in class-level

Example

- Entity

board/board.entity.ts

- Table

- @Entity() : means that "CREATE TABLE board"

- @PrimaryGeneratedColumn() : it indicates this column is PK(Primary Key) in DB, and Auto_Increment constraint

- @Column : could specify column's properties, such as length( string default : varchar(255)), and type..

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Repository

- Repository works/helps Entity CRUD tasks. 

- each Entity has its own Repository which handles all operations with its entity.

- Repository Pattern : DB tasks are assigned to Repository

Example

1. Create a repository with Entity

boards/board.repository.ts

- @EntityRepository(Board) : BoardRepository class is announced as Board's Custom Repository

- extends Repository(Board) : which entity would be controlled by this repository.

2. Register this repository as a feature in its Module

boards/boards.module.ts

- imports: [TypeOrmModule.forFeature([BoardRepository])]