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Documentation for LoopBack 4

github.com/strongloop/loopback-next/tree/master/docs

strongloop/loopback-next

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--- lang: en title: 'Add a Repository' keywords: LoopBack 4.0, LoopBack 4 sidebar: lb4_sidebar permalink: /doc/en/lb4/todo-tutorial-repository.html summary: LoopBack 4 Todo Application Tutorial - Add a Repository --- ### Repositories The repository pattern is one of the more fundamental differences between LoopBack 3 and 4. In LoopBack 3, you would use the model class definitions themselves to perform CRUD operations. In LoopBack 4, the layer responsible for this has been separated from the definition of the model itself, into the repository layer. A `Repository` represents a specialized `Service` interface that provides strong-typed data access (for example, CRUD) operations of a domain model against the underlying database or service. For more information about Repositories, see [Repositories](https://loopback.io/doc/en/lb4/Repositories.html). ### Create your repository From inside the project folder, run the `lb4 repository` command to create a repository for your to-do model using the `db` datasource from the previous step. The `db` datasource shows up by its class name `DbDataSource` from the list of available datasources. ```sh lb4 repository ? Please select the datasource DbDatasource ? Select the model(s) you want to generate a repository Todo create src/repositories/todo.repository.ts update src/repositories/index.ts ? Please select the repository base class DefaultCrudRepository (Legacy juggler bridge) Repository TodoRepository was created in src/repositories/ ``` The `src/repositories/index.ts` file makes exporting artifacts central and also easier to import. The newly created `todo.repository.ts` class has the necessary connections that are needed to perform CRUD operations for our to-do model. It leverages the Todo model definition and 'db' datasource configuration and retrieves the datasource using [Dependency Injection](https://loopback.io/doc/en/lb4/Dependency-injection.html). Now we can expose the `Todo` API through the [controller](todo-tutorial-controller.md). ### Navigation Previous step: [Add a datasource](todo-tutorial-datasource.md) Next step: [Add a controller](todo-tutorial-controller.md)