Question

我有这个实体

@Entity
public class ContactList extends Base {

    private static final long serialVersionUID = BaseEntity.serialVersionUID;

    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private Collection<User> contacts = new HashSet<User>();

    public ContactList() {
    }

    public Collection<User> getContacts() {
        return contacts;
    }

    public void setContacts(Collection<User> contacts) {
        this.contacts = contacts;
    }

}

以及我从Spring Data存储库调用的任何方法，例如findAll()，我收到此错误

java.lang.NullPointerException: null
at org.datanucleus.store.rdbms.RDBMSStoreManager.assertCompatibleFieldType(RDBMSStoreManager.java:1005) ~[datanucleus-rdbms-4.1.1.jar:na]
at org.datanucleus.store.rdbms.RDBMSStoreManager.getBackingStoreForField(RDBMSStoreManager.java:965) ~[datanucleus-rdbms-4.1.1.jar:na]
at org.datanucleus.store.rdbms.query.BulkFetchExistsHelper.getSQLStatementForContainerField(BulkFetchExistsHelper.java:93) ~[datanucleus-rdbms-4.1.1.jar:na]
at org.datanucleus.store.rdbms.query.JPQLQuery.compileQueryFull(JPQLQuery.java:894) ~[datanucleus-rdbms-4.1.1.jar:na]
at org.datanucleus.store.rdbms.query.JPQLQuery.compileInternal(JPQLQuery.java:296) ~[datanucleus-rdbms-4.1.1.jar:na]
at org.datanucleus.store.query.Query.executeQuery(Query.java:1801) ~[datanucleus-core-4.1.1.jar:na]
at org.datanucleus.store.query.Query.executeWithMap(Query.java:1747) ~[datanucleus-core-4.1.1.jar:na]
at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:197) ~[datanucleus-api-jpa-4.1.1.jar:na]
at org.springframework.data.jpa.repository.query.JpaQueryExecution$CollectionExecution.doExecute(JpaQueryExecution.java:77) ~[spring-data-jpa-1.3.0.RELEASE.jar:na]
at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:55) ~[spring-data-jpa-1.3.0.RELEASE.jar:na]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:95) ~[spring-data-jpa-1.3.0.RELEASE.jar:na]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:85) ~[spring-data-jpa-1.3.0.RELEASE.jar:na]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:312) ~[spring-data-commons-1.5.0.RELEASE.jar:na]

知道为什么吗？

我还尝试将targetEntity = User.class添加到@ManyToMany。我正在使用DataNucleus 1.4.1。

我在日志中找到了以下可能相关的行：

DataNucleus.Datastore.Schema - DEBUG: Field [ContactList.contacts] -> Column(s) [contactlist.contacts] using mapping of type "org.datanucleus.store.rdbms.mapping.java.TypeConverterMapping" (org.datanucleus.store.rdbms.mapping.datastore.VarCharRDBMSMapping) 
...
DataNucleus.Persistence - WARN : Member ContactList.contacts in table=contactlist has mapping=org.datanucleus.store.rdbms.mapping.java.TypeConverterMapping@6296ccf7 but expected mapping type=class org.datanucleus.store.rdbms.mapping.java.CollectionMapping

Answer 1

问题是自动应用Converter。但我认为这是DataNucleus的问题，因为该转换器被声明为类似

public class ListOfMyEnumsToStringAttributeConverter 
    extends CollectionOfEnumsToStringAttributeConverter<MyEnum, List<MyEnum>>
    implements AttributeConverter<List<MyEnum>, String>

DataNucleus的另一个问题是即使应该记录警告/错误消息，也会抛出NPE。

最后，但并非最不重要的是，当自动应用转换器并导致错误时，转换器类应该是日志消息的一部分。

DataNucleus中的ManyToMany上的NPE

1 个答案: