@UniqueConstraint annotation in Java

Question

I have a Java bean. Now, I want to be sure that the field should be unique.

I am using the following code:

@UniqueConstraint(columnNames={\"username\         


        

Answer 1

Unique annotation should be placed right above the attribute declaration. UniqueContraints go into the @Table annotation above the data class declaration. See below:

@Entity
@Table(uniqueConstraints= arrayOf(UniqueConstraint(columnNames = arrayOf("col_1", "col_2"))))
data class Action(
        @Id @GeneratedValue @Column(unique = true)
        val id: Long?,
        val col_1: Long?,
        val col_2: Long?,
)