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kotlinlang

Hi! I'm a bit new to ORM and DB connection in app. I've switched from DAO to DSL way because of better separation between data and code (multitier architecture). Question - what would you recommend to access values from referenced columns (like in DAO way)? I'm talking about using `data class` in higher tiers. Only possible way I could come up with is to create `Map` for every 1:N relationship, which might be very monstrous in the end. How do you usually deal with that? Thanks for the reply in advance!

Why 1:N is a `Map` not a `List`?
You may end up like this :
```
    object ParentTable : IntIdTable()
    object ChildTable : IntIdTable() {
        val parentId = reference("parentId", ParentTable)
    }
    
    data class Parent(val id: Int) {
        val children get() = ChildTable.select { ChildTable.parentId eq id }.map { Child.wrap(it) }
        
        companion object {
            fun wrap(rs: ResultRow) : Parent = Parent(rs[ParentTable.id].value)
        }
    } 
    
    data class Child(val id: Int, val parentId: Int) {
        val parent get() = ParentTable.select { ParentTable.id eq parentId }.singleOrNull()?.let { Parent.wrap(it) }
        
        companion object {
            fun wrap(rs: ResultRow) : Child = Child(rs[ChildTable.id].value, rs[ChildTable.parentId].value)
        }
    } 
```

It might be not very clear, sorry. I mostly use Exposed DAO for entities.