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One great feature of a related model’s repository is its ability to expose a factory function (a function that returns a newly instantiated object) to return a ‘constrained’ version of the related model’s repository. A factory function is useful because it allows you to create a repository whose operations are limited by the data set that applies to the factory function.

In this section, we’ll build TodoListRepository to have the capability of building a constrained version of TodoRepository.

Create your repository

From inside the project folder, run the lb4 repository command to create a repository for the TodoList model using the db datasource. The db datasource shows up by its class name DbDataSource from the list of available datasources.

lb4 repository ? Please select the datasource DbDatasource ? Select the model(s) you want to generate a repository TodoList ? Please select the repository base class DefaultCrudRepository (Juggler bridge)    create src/repositories/todo-list.repository.ts    update src/repositories/index.ts  Repository TodoListRepository was created in src/repositories/

Custom Methods

A custom method can be added to the repository class. For example, if we want to find a TodoList with a specific title from the repository level, the following method can be added:

export class TodoListRepository extends DefaultCrudRepository<   TodoList,   typeof TodoList.prototype.id,   TodoListRelations > {   // other code    // Add the following function   public findByTitle(title: string) {     return this.findOne({where: {title}});   } }

To view the completed file, see the TodoList example.

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