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Separating db engine and core (#3)
Separating core and db egine * Core, Slick and example classes seperated * Removed some unnecessary classes * Clearer placement for NamingConventions implicits * Documentation on core classes
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‎src/main/scala/za/co/absa/fadb/DBExecutor.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb
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import za.co.absa.fadb.DBFunction.QueryFunction
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import scala.concurrent.Future
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/**
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* And abstraction to make it possible to execute queries through regardless of the provided database engine library
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*
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* @tparam E - the type of the engine, E.g. a Slick Postgres Database
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*/
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trait DBExecutor[+E] {
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def run[R](fnc: QueryFunction[E, R]): Future[Seq[R]]
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}

‎src/main/scala/za/co/absa/fadb/DBFunction.scala‎

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/*
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* Copyright 2021 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb
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import za.co.absa.fadb.DBFunction.QueryFunction
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import scala.concurrent.Future
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/**
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* The most general abstraction of database function representation
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* The database name of the function is derives from the class name based on the provided naming convention (in schema)
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*
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* @param schema - the schema the function belongs into
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* @param functionNameOverride - in case the class name would not match the database function name, this gives the
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* possibility of override
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* @tparam E - the type of the [[DBExecutor]] engine
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* @tparam T - the type covering the input fields of the database function
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* @tparam R - the type covering the returned fields from the database function
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*/
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abstract class DBFunction[E, T, R](schema: DBSchema[E], functionNameOverride: Option[String] = Some("a")) {
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val functionName: String = {
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val fn = functionNameOverride.getOrElse(schema.objectNameFromClassName(getClass))
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if (schema.schemaName.isEmpty) {
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fn
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} else {
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s"${schema.schemaName}.$fn"
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}
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}
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protected def queryFunction(values: T): QueryFunction[E, R]
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}
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object DBFunction {
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type QueryFunction[E, R] = E => Future[Seq[R]]
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/**
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* Represents a function returning a set (in DB sense) of rows
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*
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* @param schema - the schema the function belongs into
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* @param functionNameOverride - in case the class name would not match the database function name, this gives the
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* possibility of override
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* @tparam E - the type of the [[DBExecutor]] engine
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* @tparam T - the type covering the input fields of the database function
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* @tparam R - the type covering the returned fields from the database function
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*/
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abstract class DBSeqFunction[E, T, R](schema: DBSchema[E], functionNameOverride: Option[String] = None)
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extends DBFunction[E, T, R](schema, functionNameOverride) {
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def apply(values: T): Future[Seq[R]] = {
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schema.execute(queryFunction(values))
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}
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}
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/**
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* Represents a function returning exactly one record
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*
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* @param schema - the schema the function belongs into
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* @param functionNameOverride - in case the class name would not match the database function name, this gives the
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* possibility of override
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* @tparam E - the type of the [[DBExecutor]] engine
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* @tparam T - the type covering the input fields of the database function
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* @tparam R - the type covering the returned fields from the database function
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*/
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abstract class DBUniqueFunction[E, T, R](schema: DBSchema[E], functionNameOverride: Option[String] = None)
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extends DBFunction[E, T, R](schema, functionNameOverride) {
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def apply(values: T): Future[R] = {
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schema.unique(queryFunction(values))
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}
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}
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/**
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* Represents a function returning one optional record
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*
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* @param schema - the schema the function belongs into
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* @param functionNameOverride - in case the class name would not match the database function name, this gives the
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* possibility of override
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* @tparam E - the type of the [[DBExecutor]] engine
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* @tparam T - the type covering the input fields of the database function
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* @tparam R - the type covering the returned fields from the database function
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*/
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abstract class DBOptionFunction[E, T, R](schema: DBSchema[E], functionNameOverride: Option[String] = None)
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extends DBFunction[E, T, R](schema, functionNameOverride) {
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def apply(values: T): Future[Option[R]] = {
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schema.option(queryFunction(values))
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}
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}
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}

‎src/main/scala/za/co/absa/fadb/DBSchema.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb
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import za.co.absa.fadb.naming_conventions.NamingConvention
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import scala.concurrent.Future
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import scala.concurrent.ExecutionContext.Implicits.global
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/**
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* An abstract class, an ancestor to represent a database schema (each database function should be placed in a schema)
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* The database name of the schema is derives from the class name based on the provided naming convention
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*
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* @param executor - executor to execute the queries through
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* @param schemaNameOverride - in case the class name would not match the database schema name, this gives the
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* possibility of override
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* @param namingConvention - the [[NamingConvention]] prescribing how to convert a class name into a db object name
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* @tparam E - the engine of the executor type, e.g. Slick [[Database]]
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*/
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abstract class DBSchema[E](val executor: DBExecutor[E], schemaNameOverride: Option[String] = None)
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(implicit namingConvention: NamingConvention) {
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def objectNameFromClassName(c: Class[_]): String = {
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namingConvention.fromClassNamePerConvention(c)
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}
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val schemaName: String = schemaNameOverride.getOrElse(objectNameFromClassName(getClass))
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def execute[R](query: E => Future[Seq[R]]): Future[Seq[R]] = {
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executor.run(query)
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}
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def unique[R](query: E => Future[Seq[R]]): Future[R] = {
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for {
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all <- execute(query)
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} yield all.head
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}
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def option[R](query: E => Future[Seq[R]]): Future[Option[R]] = {
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for {
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all <- execute(query)
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} yield all.headOption
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}
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}

‎src/main/scala/za/co/absa/fadb/examples/enceladus/DatasetSchema.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb.examples.enceladus
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import za.co.absa.fadb.DBSchema
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import za.co.absa.fadb.slick.{SlickPgExecutor, SlickPgFunction}
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import za.co.absa.fadb.naming_conventions.SnakeCaseNaming.Implicits.namingConvention
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import slick.jdbc.GetResult
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import za.co.absa.fadb.DBFunction._
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import slick.jdbc.PostgresProfile.api._
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import za.co.absa.fadb.exceptions.DBFailException
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import java.sql.Timestamp
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import scala.concurrent.Future
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import DatasetSchema._
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class DatasetSchema(executor: SlickPgExecutor) extends DBSchema(executor) {
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private implicit val schema: DBSchema[ExecutorEngineType] = this
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val addSchema = new AddSchema
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val getSchema = new GetSchema
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val listSchemas = new ListSchemas
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}
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object DatasetSchema {
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type ExecutorEngineType = Database
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case class SchemaInput(schemaName: String,
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schemaVersion: Int,
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schemaDescription: Option[String],
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fields: Option[String],
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userName: String)
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case class Schema(idSchemaVersion: Long,
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schemaName: String,
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schemaVersion: Int,
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schemaDescription: Option[String],
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fields: Option[String],
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createdBy: String,
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createdWhen: Timestamp,
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updatedBy: String,
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updatedWhen: Timestamp,
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lockedBy: Option[String],
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lockedWhen: Option[Timestamp],
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deletedBy: Option[String],
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deletedWhen: Option[Timestamp])
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case class SchemaHeader(schemaName: String, schemaLatestVersion: Int)
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private implicit val SchemaHeaderImplicit: GetResult[SchemaHeader] = GetResult(r => {SchemaHeader(r.<<, r.<<)})
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private implicit val GetSchemaImplicit: GetResult[Schema] = GetResult(r => {
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val status: Int = r.<<
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val statusText: String = r.<<
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if (status != 200) {
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throw DBFailException(status, statusText)
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}
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Schema(r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<, r.<<)
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})
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final class AddSchema(implicit schema: DBSchema[ExecutorEngineType])
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extends DBUniqueFunction[ExecutorEngineType, SchemaInput, Long](schema)
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with SlickPgFunction {
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override protected def queryFunction(values: SchemaInput): QueryFunction[ExecutorEngineType, Long] = {
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val gr:GetResult[Long] = GetResult(r => {
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val status: Int = r.<<
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val statusText: String = r.<<
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if (status != 201) throw DBFailException(status, statusText)
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r.<<
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})
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val sql =
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sql"""SELECT A.status, A.status_text, A.id_schema_version
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FROM #$functionName(${values.schemaName}, ${values.schemaVersion}, ${values.schemaDescription},
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${values.fields}::JSONB, ${values.userName}
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) A;"""
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makeQueryFunction(sql)(gr)
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}
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}
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final class GetSchema(implicit schema: DBSchema[ExecutorEngineType])
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extends DBUniqueFunction[ExecutorEngineType, (String, Option[Int]), Schema](schema)
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with SlickPgFunction {
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def apply(id: Long): Future[Schema] = {
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val sql =
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sql"""SELECT A.*
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FROM #$functionName($id) A;"""
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schema.unique(makeQueryFunction[Schema](sql))
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}
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override protected def queryFunction(values: (String, Option[Int])): QueryFunction[ExecutorEngineType, Schema] = {
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val sql =
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sql"""SELECT A.*
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FROM #$functionName(${values._1}, ${values._2}) A;"""
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makeQueryFunction[Schema](sql)
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}
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}
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final class ListSchemas(implicit schema: DBSchema[ExecutorEngineType])
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extends DBSeqFunction[ExecutorEngineType, Boolean, SchemaHeader](schema)
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with SlickPgFunction {
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override def apply(values: Boolean = false): Future[Seq[SchemaHeader]] = super.apply(values)
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override protected def queryFunction(values: Boolean): QueryFunction[ExecutorEngineType, SchemaHeader] = {
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val sql =
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sql"""SELECT A.schema_name, A.schema_latest_version
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FROM #$functionName($values) as A;"""
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makeQueryFunction[SchemaHeader](sql)
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}
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}
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}

‎src/main/scala/za/co/absa/fadb/exceptions/DBFailException.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb.exceptions
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case class DBFailException(status: Int, message: String) extends Exception(message)

‎src/main/scala/za/co/absa/fadb/exceptions/NamingException.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb.exceptions
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case class NamingException(message: String) extends Exception(message)

‎src/main/scala/za/co/absa/fadb/naming_conventions/AsIsNaming.scala‎

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/*
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* Copyright 2022 ABSA Group Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package za.co.absa.fadb.naming_conventions
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import za.co.absa.fadb.naming_conventions.letters_case.LettersCase
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import za.co.absa.fadb.naming_conventions.letters_case.LettersCase.AsIs
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class AsIsNaming(lettersCase: LettersCase) extends NamingConvention{
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override def stringPerConvention(original: String): String = {
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lettersCase.convert(original)
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}
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}
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object AsIsNaming {
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object Implicits {
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implicit val namingConvention: NamingConvention = new AsIsNaming(AsIs)
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}
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}

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