Auto Migrations

README.md

@@ -28,7 +28,7 @@ Installation
 Add the following dependency to your project's build.gradle file:
 
 ```kts
-implementation('app.meetacy.wdater:wdater:$wdaterVersion')
+implementation("app.meetacy.wdater:wdater:$wdaterVersion")
 ```
 
 Replace `$wdaterVersion` with the latest version from release.
@@ -81,13 +81,7 @@ Usage
 
     ```kotlin
     object UsersTable : Table() {
-        val USER_ID = long("USER_ID").autoIncrement()
-        val ACCESS_HASH = varchar("ACCESS_HASH", length = HASH_LENGTH)
-        val NICKNAME = varchar("NICKNAME", length = NICKNAME_MAX_LIMIT)
         val USERNAME = varchar("USERNAME", length = USERNAME_MAX_LIMIT).nullable()
-        val EMAIL = varchar("EMAIL", length = EMAIL_MAX_LIMIT).nullable()
-        val EMAIL_VERIFIED = bool("EMAIL_VERIFIED").default(false)
-        val AVATAR_ID = long("AVATAR_ID").nullable()
     }
     ```
 
@@ -101,6 +95,24 @@ Usage
 
     You can also pass a list of migrations to update multiple steps at once.
 
+Auto Migrations
+---------------
+
+To use automatic migrations, you need to include this dependency:
+
+```kts
+implementation("app.meetacy.wdater:auto-migrations:$wdaterVersion")
+```
+
+Then you can use this factory function to create a migration:
+
+```kotlin
+fun AutoMigration(
+    vararg tables: Table,
+    fromVersion: Int,
+    toVersion: Int = fromVersion + 1
+): AutoMigration
+```
 
 Future Plans for Wdater
 -----------------------

auto-migrations/build.gradle.kts

@@ -0,0 +1,10 @@
+plugins {
+    id("library-convention")
+}
+
+version = libs.versions.wdater.get()
+
+dependencies {
+    implementation(libs.exposedCore)
+    api(projects.wdater)
+}

auto-migrations/src/main/kotlin/app/meetacy/database/updater/auto/AutoMigration.kt

@@ -0,0 +1,169 @@
+package app.meetacy.database.updater.auto
+
+import app.meetacy.database.updater.Migration
+import app.meetacy.database.updater.MigrationContext
+import app.meetacy.database.updater.log.Logger
+import app.meetacy.database.updater.log.SQL
+import org.jetbrains.exposed.sql.*
+import org.jetbrains.exposed.sql.vendors.ColumnMetadata
+
+public fun AutoMigration(
+    vararg tables: Table,
+    fromVersion: Int,
+    toVersion: Int = fromVersion + 1
+): AutoMigration = AutoMigration(tables.toList(), fromVersion, toVersion)
+
+/**
+ * Auto migrations do not support renaming/deleting
+ */
+public class AutoMigration(
+    private val tables: List<Table>,
+    override val fromVersion: Int,
+    override val toVersion: Int = fromVersion + 1
+) : Migration {
+
+    override suspend fun MigrationContext.migrate() {
+        logger.log("Trying to auto migrate from current state")
+        migrateTables()
+        migrateColumns()
+    }
+
+    private fun MigrationContext.migrateTables() {
+        logger.log("Migrating tables...")
+        val logger = logger["tables-migration"]
+
+        val rawNames = transaction.db.dialect.allTablesNames()
+        logger.log("Tables from server: $rawNames")
+        val schema = transaction.connection.schema
+        logger.log("Default schema: $schema")
+
+        val tablesOnServer = rawNames.map { name -> name.removePrefix("$schema.") }
+
+        createMissingTables(logger, tablesOnServer)
+    }
+
+    private fun MigrationContext.createMissingTables(
+        baseLogger: Logger,
+        tablesOnServer: List<String>
+    ) {
+        baseLogger.log("Creating missing tables...")
+        val logger = baseLogger["create"]
+
+        val newTables = tables.filter { table ->
+            tablesOnServer.none { name -> normalizedTableName(table) == name }
+        }
+
+        if (newTables.isEmpty()) {
+            logger.log("No new tables were found")
+            return
+        }
+
+        logger.log("New tables were found: $newTables, creating them...")
+
+        val create = SchemaUtils.createStatements(*newTables.toTypedArray())
+        execInBatch(logger, create)
+
+        logger.log("New tables were created")
+    }
+
+    private fun MigrationContext.migrateColumns() {
+        logger.log("Migrating columns...")
+        val logger = logger["columns-migration"]
+        val columnsOnServer = transaction.db.dialect.tableColumns(*tables.toTypedArray())
+        createMissingColumns(logger, columnsOnServer)
+        val updatedColumnOnServer = transaction.db.dialect.tableColumns(*tables.toTypedArray())
+        modifyAllColumns(logger, updatedColumnOnServer)
+        logger.log("Migration completed!")
+    }
+
+    private fun MigrationContext.createMissingColumns(
+        baseLogger: Logger,
+        databaseColumns: Map<Table, List<ColumnMetadata>>
+    ) {
+        baseLogger.log("Creating missing columns...")
+        val parentLogger = baseLogger["create"]
+
+        tables.forEach { table ->
+            parentLogger.log("Working on: ${normalizedTableName(table)}")
+
+            val logger = parentLogger[normalizedTableName(table)]
+            val columnsOnServer = databaseColumns.getValue(table)
+
+            val newColumns = table.columns.filter { column ->
+                columnsOnServer.none { metadata -> normalizedColumnName(column) == metadata.name }
+            }
+
+            if (newColumns.isEmpty()) {
+                logger.log("No new columns were found")
+                return@forEach
+            }
+
+            logger.log("New columns were found: ${newColumns.map { normalizedColumnName(it) } }, creating them...")
+
+            val create = newColumns.flatMap { column -> column.createStatement() }
+            execInBatch(logger, create)
+
+            logger.log("New columns were created")
+        }
+    }
+
+    private fun MigrationContext.modifyAllColumns(
+        baseLogger: Logger,
+        databaseColumns: Map<Table, List<ColumnMetadata>>
+    ) {
+        baseLogger.log("Modifying all columns...")
+        val parentLogger = baseLogger["modify-all"]
+
+        tables.forEach { table ->
+            parentLogger.log("Working on ${normalizedTableName(table)}")
+            val logger = parentLogger[normalizedTableName(table)]
+
+            val columnsOnServer = databaseColumns.getValue(table)
+
+            val modify = table.columns.map { column ->
+                column to columnsOnServer.first { it.name == normalizedColumnName(column) }
+            }.flatMap { (column, columnOnServer) ->
+                // exposed doesn't support migration of auto inc
+                if (column.columnType.isAutoInc) return@flatMap emptyList()
+
+                column.modifyStatements(
+                    ColumnDiff(
+                        nullability = column.columnType.nullable != columnOnServer.nullable,
+                        autoInc = false,
+                        defaults = true,
+                        caseSensitiveName = true
+                    )
+                )
+            }
+            execInBatch(logger, modify)
+            logger.log("Columns were modified")
+        }
+    }
+
+    private fun MigrationContext.execInBatch(
+        baseLogger: Logger,
+        statements: List<String>
+    ) {
+        statements.forEach(baseLogger.SQL::log)
+        transaction.execInBatch(statements)
+    }
+
+    private fun MigrationContext.normalizedTableName(table: Table): String {
+        return table.nameInDatabaseCase().removePrefix("${transaction.connection.schema}.")
+    }
+
+    private fun MigrationContext.normalizedColumnName(column: Column<*>): String {
+        return column.nameInDatabaseCase()
+    }
+
+    override val displayName: String = "AutoMigration"
+
+    private fun MigrationContext.cannotMigrate(): Nothing {
+        transaction.rollback()
+        throw CannotAutoMigrateException()
+    }
+
+    public class CannotAutoMigrateException : RuntimeException(
+        /* message = */"Ambiguity occurred while migrating, cannot make auto migration for current state"
+    )
+}

auto-migrations/src/main/kotlin/app/meetacy/database/updater/auto/NoOpColumnType.kt

@@ -0,0 +1,7 @@
+package app.meetacy.database.updater.auto
+
+import org.jetbrains.exposed.sql.ColumnType
+
+internal object NoOpColumnType : ColumnType() {
+    override fun sqlType(): String = error("No operation")
+}

auto-migrations/src/main/kotlin/app/meetacy/database/updater/auto/Table.kt

@@ -0,0 +1,13 @@
+package app.meetacy.database.updater.auto
+
+import org.jetbrains.exposed.sql.Table
+
+internal fun Table.dropColumnStatement(columnName: String): List<String> {
+    val column = Table(tableName).registerColumn<Nothing>(columnName, NoOpColumnType)
+    return column.dropStatement()
+}
+
+internal fun Table.createColumnStatement(columnName: String): List<String> {
+    val column = Table(tableName).registerColumn<Nothing>(columnName, NoOpColumnType)
+    return column.createStatement()
+}

auto-migrations/src/main/kotlin/app/meetacy/database/updater/auto/TableName.kt

@@ -0,0 +1,11 @@
+package app.meetacy.database.updater.auto
+
+internal data class TableName(
+    val schema: Schema,
+    val name: String
+) {
+    sealed interface Schema {
+        object Default : Schema
+        data class Custom(val string: String) : Schema
+    }
+}

gradle/libs.versions.toml

@@ -2,7 +2,7 @@
 
 kotlin = "1.8.10"
 exposed = "0.41.1"
-wdater = "0.0.1"
+wdater = "0.0.2"
 
 [libraries]
 

settings.gradle.kts

@@ -17,3 +17,5 @@ dependencyResolutionManagement {
 }
 
 includeBuild("build-logic")
+
+include("auto-migrations")

src/main/kotlin/app/meetacy/database/updater/Migration.kt

@@ -15,6 +15,11 @@ public interface Migration {
      */
     public val toVersion: Int get() = fromVersion + 1
 
+    /**
+     * The string used as name when printing this migration
+     */
+    public val displayName: String get() = "Migration"
+
     /**
      * Function that defines the migration logic
      */

src/main/kotlin/app/meetacy/database/updater/MigrationContext.kt

@@ -1,5 +1,6 @@
 package app.meetacy.database.updater
 
+import app.meetacy.database.updater.log.Logger
 import org.jetbrains.exposed.sql.Column
 import org.jetbrains.exposed.sql.Table.Dual.default
 import org.jetbrains.exposed.sql.Transaction
@@ -10,7 +11,10 @@ import org.jetbrains.exposed.sql.Transaction
  *
  * @param transaction The database transaction in which the migration is executed.
  */
-public class MigrationContext(public val transaction: Transaction) {
+public class MigrationContext(
+    public val transaction: Transaction,
+    public val logger: Logger
+) {
 
     /**
      * Creates the column in the associated table.