Skate is a SQL generation and query library for Kotlin. It makes it easy to get your data as Kotlin data classes without the pitfalls of an ORM.
Entity
An entity is a data class that represents a row in a database table. Use the @TableName annotation to specify the table name.@TableName(“users”) data class User( override val id: UUID = UUID.randomUUID(), val name: String? = null, val email: String? = null, val createdAt: OffsetDateTime = OffsetDateTime.now(), val updatedAt: OffsetDateTime? = null, ) : Entity
Generating SQL
Only the Postgresql generator is currently supported. It’s easy to add more generators if you need them.val psql = skate.generator.Postgresql()
Use selectAll to fetch all fields in a table.User::class .selectAll() .where(User::email eq “john@doe.com”) .generate(psql)sql: SELECT * FROM “users” WHERE “email” = ? values: [“john@doe”]
Use insert to add a list of entities to a table.User::class .insert() // can specify which fields to insert here .values(User(name = “John Doe”, email = “john@doe.com”)) .generate(psql)sql: INSERT INTO “users” (“created_at”, “email”, “id”, “name”, “updated_at”) VALUES (#users0.createdAt, #users0.email, #users0.id, #users0.name, #users0.updatedAt) values: [User(…)]
Unlike an ORM, update requires you to specify exactly which fields to update.User::class .update( User::name to “Jane Doe”, User::email to “jane@doe.com” ) .where(User::email eq “john@doe.com”) .generate(psql)sql: UPDATE “users” SET “name” = ?, “email” = ? WHERE (“email” = ?) values: [“Jane Doe”, “jane@doe”, “john@doe”]
Use delete to delete rows from a table. But usually you’ll want to use update to set a deletedAt field instead.Users::class .delete() .where(User::id.eq(id)) .generate(psql)sql: DELETE FROM “users” WHERE (“id” = ?) values: UUID(…)
Querying
Executing generated SQL in the database just requires calling either query or execute depending on whether you want to observe the results.User::class .selectAll() .where(User::name.like(“John %”)) .generate(psql) .query(jdmiHandle, timeoutSeconds = 10)List<User>(…)