Created
June 9, 2022 14:47
-
-
Save Daenyth/ac268350c5dc57e7a8871152e87eaf93 to your computer and use it in GitHub Desktop.
Doobie code structure example
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| package myapp.users | |
| // This is the shape of code I've found to work best for doobie in a cats-effect application using capability traits | |
| trait UserOnboarding[F[_]] { | |
| // The api expresses the business-level workflow, not the implementation of inserting to a database | |
| // Keep the interface expressing the high level concern; database is only *one* implementation and it can change later | |
| def registerUser(userInfo: UserInfo): F[UserId] | |
| } | |
| class DbUserOnboarding[F[_]: MonadThrow]( | |
| xa: Transactor[F], | |
| email: EmailService[F] | |
| ) extends BusinessLogic[F] { | |
| import DbUserOnboarding.queries | |
| // DbUserOnboarding is responsible for structuring transactions and the things that happen around them | |
| def registerUser(userInfo: UserInfo): F[UserId] = | |
| queries | |
| .registerUser(userInfo) | |
| .withUniqueGeneratedKeys[Int]("id") | |
| .transact(xa) >> email.notifySuccessfulRegistration(userInfo) | |
| } | |
| object DbUserOnboarding { | |
| // Queries are rarely generic/reusable across business domains in practice | |
| // Because our interface is around the business domain and not the database shape, | |
| // our queries can be private | |
| // We make the package-private for the sole purpose of unit testing the query correctness | |
| private[users] object queries { | |
| // queries all return Update0 / Query0 for doobie `check` tests | |
| def registerUser(userInfo: UserInfo): Update0 = | |
| sql"INSERT INTO users (name, email) VALUES (${userInfo.name}, ${userInfo.email})".update | |
| } | |
| } | |
| // Unit tests on db interactions should primarily be `check` calls for simple CRUD operations | |
| // full-scale cross-transaction tests are slow and non-parallelizable. Avoid them for everything except critical logic-heavy queries | |
| // which have a high risk of bugs or dangerous impact if bugs happen |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment