Spring JPA cannot map a field with custom setter in a Kotlin data class - spring

Question

I've got a Kotlin data class with a custom setter. The Spring JPA framework cannot seem to map the property with the custom setter. If I remove the custom getter/setter and rename the property to login instead of _login, everything seems to work fine. How can I create the property in the Kotlin data class with a custom setter, so that it is recognised in the JPA framework?
User.kt
#Entity
#Table(name = "jhi_user")
#Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
data class User (
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "sequenceGenerator")
#SequenceGenerator(name = "sequenceGenerator")
var id: Long? = null,
#NotNull
#Pattern(regexp = Constants.LOGIN_REGEX)
#Size(min = 1, max = 50)
#Column(name = "login", length = 50, unique = true, nullable = false)
var _login: String? = null,
#JsonIgnore
#NotNull
#Size(min = 60, max = 60)
#Column(name = "password_hash",length = 60)
var password: String? = null,
...
#JsonIgnore
#ManyToMany
#JoinTable(
name = "jhi_user_authority",
joinColumns = arrayOf(JoinColumn(name = "user_id", referencedColumnName = "id")),
inverseJoinColumns = arrayOf(JoinColumn(name = "authority_name", referencedColumnName = "name")))
#Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
#BatchSize(size = 20)
var authorities: MutableSet<Authority>? = null): AbstractAuditingEntity(), Serializable {
//Lowercase the login before saving it in database
var login: String?
get() = _login
set(value) {
_login = StringUtils.lowerCase(value, Locale.ENGLISH)
}
}
The error I'm getting:
...
Caused by: java.lang.IllegalArgumentException: Unable to locate Attribute with the the given name [login] on this ManagedType [com.sample.domain.AbstractAuditingEntity]
at org.hibernate.metamodel.internal.AbstractManagedType.checkNotNull(AbstractManagedType.java:128)
at org.hibernate.metamodel.internal.AbstractManagedType.getAttribute(AbstractManagedType.java:113)
at org.hibernate.metamodel.internal.AbstractManagedType.getAttribute(AbstractManagedType.java:111)
at org.springframework.data.jpa.repository.query.QueryUtils.toExpressionRecursively(QueryUtils.java:569)
at org.springframework.data.jpa.repository.query.JpaQueryCreator$PredicateBuilder.getTypedPath(JpaQueryCreator.java:377)
at org.springframework.data.jpa.repository.query.JpaQueryCreator$PredicateBuilder.build(JpaQueryCreator.java:300)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.toPredicate(JpaQueryCreator.java:205)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:117)
at org.springframework.data.jpa.repository.query.JpaQueryCreator.create(JpaQueryCreator.java:54)
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createCriteria(AbstractQueryCreator.java:111)
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:90)
at org.springframework.data.repository.query.parser.AbstractQueryCreator.createQuery(AbstractQueryCreator.java:78)
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$QueryPreparer.<init>(PartTreeJpaQuery.java:135)
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery$CountQueryPreparer.<init>(PartTreeJpaQuery.java:256)
at org.springframework.data.jpa.repository.query.PartTreeJpaQuery.<init>(PartTreeJpaQuery.java:72)
at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:103)

Answer 1

Using custom setters for constructor parameters like this is a bit ugly (but unfortunately the only way I am aware of doing it).
For starters JPA is going to want to register both _login and login as separate columns in your database since neither of them are #Transient. I believe your issue arises here since you have marked the _login property to map to the column "login" whereas the login property has no #Column annotation so it is trying to map to it's default value of "login" which already has the _login property mapped to it.
Therefore I think you probably want to make _login transient and only persist login (I've missed out irrelevant code for brevity and clarity):
...
#Transient
var _login: String? = null,
...
#NotNull
#Pattern(regexp = Constants.LOGIN_REGEX)
#Size(min = 1, max = 50)
#Column(name = "login", length = 50, unique = true, nullable = false)
var login: String?
get() = _login
set(value) {
_login = StringUtils.lowerCase(value, Locale.ENGLISH)
}
If this still doesn't work then I really think it's more hassle than it's worth trying to get this already slightly hacky workaround for using custom setters on constructor properties working with JPA. I would suggest instead to use a #PrePersist/#PreUpdate method to do the lowercasing for you prior to saving it to the database.