KomapperでWhere宣言を合成する例

where-declaration-composition.kt

package org.komapper.quickstart

import org.komapper.annotation.KomapperAutoIncrement
import org.komapper.annotation.KomapperEntity
import org.komapper.annotation.KomapperId
import org.komapper.core.dsl.EntityDsl
import org.komapper.core.dsl.SchemaDsl
import org.komapper.core.dsl.expression.ColumnExpression
import org.komapper.core.dsl.scope.WhereDeclaration
import org.komapper.jdbc.JdbcDatabase
import org.komapper.tx.jdbc.withTransaction

// 年齢を表すクラス
@JvmInline
value class Age(val value: Int)

// 人を表すエンティティクラス
@KomapperEntity
data class Person(
    @KomapperId @KomapperAutoIncrement
    val id: Int = 0,
    val name: String,
    val age: Age
) {
    companion object
}

// 成年の検索条件
fun ColumnExpression<Age, Int>.adult(): WhereDeclaration = {
    this@adult greaterEq Age(20)
}

// 生産年齢の検索条件
fun ColumnExpression<Age, Int>.workingAge(): WhereDeclaration = {
    this@workingAge less Age(65)
    and(adult()) // 成年の検索条件を再利用
}

fun main() {
    val db = JdbcDatabase.create("jdbc:h2:mem:quickstart;DB_CLOSE_DELAY=-1")

    db.withTransaction {
        val p = Person.meta

        // スキーマ作成
        db.runQuery { SchemaDsl.create(p) }

        // データを3件追加
        db.runQuery {
            EntityDsl.insert(p).multiple(
                Person(name = "aaa", age = Age(10)),
                Person(name = "bbb", age = Age(30)),
                Person(name = "ccc", age = Age(70)),
            )
        }

        println("成年の定義で検索")
        db.runQuery { EntityDsl.from(p).where(p.age.adult()) }.forEach {
            println(it)
        }

        println("生産年齢の定義で検索")
        db.runQuery { EntityDsl.from(p).where(p.age.workingAge()) }.forEach {
            println(it)
        }
    }
}

出力結果

17:22:41.477 [main] DEBUG org.komapper.SQL - insert into person (name, age) values (?, ?), (?, ?), (?, ?)
成年の定義で検索
17:22:41.513 [main] DEBUG org.komapper.SQL - select t0_.id, t0_.name, t0_.age from person as t0_ where t0_.age >= ?
Person(id=2, name=bbb, age=Age(value=30))
Person(id=3, name=ccc, age=Age(value=70))
生産年齢の定義で検索
17:22:41.567 [main] DEBUG org.komapper.SQL - select t0_.id, t0_.name, t0_.age from person as t0_ where t0_.age < ? and (t0_.age >= ?)
Person(id=2, name=bbb, age=Age(value=30))