How do I check columns for null or set them to nul...

# exposed

[martmists]

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 <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]

Add .nullable() to the column definition

[dave08]

except for reference then use optReference

[martmists]

as you can see that's what I did

[dave08]

You have a reference to the CommentTable itself?

[dave08]

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

[dave08]

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

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?

[dave08]

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

[dave08]

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?

[dave08]

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

[martmists]

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

[dave08]

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

[martmists]

nope