| name | add-repository |
| description | Add a repository to :data:core as composable single-unit repositories ([Verb][Name]Repository) encapsulated by a parent contract, each mapping a data source's RemoteResult into DataResult. Use when asked to "add a repository", "wire up a repository", or to expose data-layer operations to domain/presentation. |
Add a repository
Like a data source, a repository is not one class with many methods — it is a
set of single-unit repositories (one operation each), encapsulated by a
parent repository contract. Each unit consumes the data source, maps its DTO
to a data model, and returns DataResult.
Why this shape
- Single responsibility: one type = one operation.
- Testability: each unit takes a data source it can be handed a fake of —
no network, no Koin (see
add-repository-test).
Naming & layout
- Single unit —
[Verb][Name]Repository (e.g. GetCharacterRepository): a
fun interface contract + an internal impl, in the same file. Returns
DataResult<Model>.
- Parent —
[Feature]Repository (e.g. CharacterRepository): an interface
exposing each child as a val, + an internal impl that overrides them as
constructor parameters, in the same file.
- Lives in
:data:core, package ...data.<feature>. Model in ...data.model,
the toData() mapper in ...data.mappers (see add-dto-mapper).
- DIP: contracts are public, impls are
internal. A unit depends on the data
source's parent contract (CharacterRemoteDatasource) — never a single-unit
data source or an impl.
Steps
1. Data model + mapper
Add the model in ...data.model and the toData() mapper in ...data.mappers
(see add-dto-mapper).
2. Single-unit repository (contract + impl, one file)
...data.<feature>/GetCharacterRepository.kt:
fun interface GetCharacterRepository {
suspend operator fun invoke(id: Int): DataResult<Character>
}
internal class GetCharacterRepositoryImpl(
private val remoteDatasource: CharacterRemoteDatasource,
) : GetCharacterRepository {
override suspend fun invoke(id: Int): DataResult<Character> =
remoteDatasource.getCharacter(id).toDataResult { it.toData() }
}
One file per operation; repeat for GetCharactersRepository, etc.
3. Parent repository (contract + impl, one file)
...data.<feature>/CharacterRepository.kt. The impl just holds the children:
interface CharacterRepository {
val getCharacter: GetCharacterRepository
val getCharacters: GetCharactersRepository
}
internal class CharacterRepositoryImpl(
override val getCharacter: GetCharacterRepository,
override val getCharacters: GetCharactersRepository,
) : CharacterRepository
Consumers (use cases, ViewModels) depend on the parent and call a unit straight
through: characterRepository.getCharacter(id) — the val is invoked via its
operator fun invoke.
4. Bind it in repositoryModule
:data:core .../data/di/RepositoryModule.kt (replace the TODO). singleOf
autowires each impl's data source / children from the graph:
import org.koin.core.module.dsl.singleOf
import org.koin.dsl.bind
internal val repositoryModule = module {
singleOf(::GetCharacterRepositoryImpl) { bind<GetCharacterRepository>() }
singleOf(::GetCharactersRepositoryImpl) { bind<GetCharactersRepository>() }
singleOf(::CharacterRepositoryImpl) { bind<CharacterRepository>() }
}
repositoryModule is already included by dataModule.
Verify
./gradlew :data:core:compileDebugSources --console=plain
(Set JAVA_HOME to a JDK 21 — e.g. an SDKMAN *-jbr — if the shell can't find
Java.)
Checklist
