How do I check columns for null or set them to nullable values table ```object CommentTable LongIdTable val post = reference post PostTable val parent = optReference parent CommentTable val author = reference author UserTable val content = text content val created = datetime created val updated = datetime updated ``` but when doing `CommentTable parent eq null` I get ```Overload resolution ambiguity public open fun lt T Comparable lt TypeVariable T gt E EntityID lt TypeVariable T gt gt ExpressionWithColumnType lt TypeVariable E gt eq t TypeVariable T Op lt Boolean gt defined in org jetbrains exposed sql SqlExpressionBuilder public open fun lt T gt ExpressionWithColumnType lt TypeVariable T gt eq t TypeVariable T Op lt Boolean gt defined in org jetbrains exposed sql SqlExpressionBuilder```

object CommentTable : LongIdTable() {
    val post = reference("post", PostTable)
    val parent = optReference("parent", CommentTable)
    val author = reference("author", UserTable)
    val content = text("content")
    val created = datetime("created")
    val updated = datetime("updated")
}

but when doing

CommentTable.parent eq null

I get

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Overload resolution ambiguity: 
public open fun <T : Comparable<TypeVariable(T)>, E : EntityID<TypeVariable(T)>?> ExpressionWithColumnType<TypeVariable(E)>.eq(t: TypeVariable(T)?): Op<Boolean> defined in org.jetbrains.exposed.sql.SqlExpressionBuilder
public open fun <T> ExpressionWithColumnType<TypeVariable(T)>.eq(t: TypeVariable(T)): Op<Boolean> defined in org.jetbrains.exposed.sql.SqlExpressionBuilder

dave08

01/19/2022, 2:11 PM

Add

.nullable()

to the column definition

except for

reference

then use

optReference

martmists

01/19/2022, 2:28 PM

as you can see that's what I did

✔️ 1

dave08

01/19/2022, 2:29 PM

You have a reference to the CommentTable itself?

I think there's a special construct for that...

In the DAO docs there's this for parent-child references

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object NodeTable : IntIdTable() {
    val name = varchar("name", 50)
}
object NodeToNodes : Table() {
    val parent = reference("parent_node_id", NodeTable)
    val child = reference("child_user_id", NodeTable)
}

I wonder if the fact you're referencing the table itself causes the problem?

Ooh... it seems not to know which of the two overloads to use...

The parent column is an

EntityID

not an

Int

by the way. So maybe there's some kind of empty instance of it to denote null instead of

null

I don't have my project using exposed open now, so I can't really check...

martmists

01/19/2022, 2:49 PM

The EntityID is nullable though, so why would it be a non-null value?

dave08

01/19/2022, 2:50 PM

And you can't even set it to null in an update statement?

martmists

01/19/2022, 3:21 PM

nope

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