Hibernate Parent-Child One-To-Many Relationship -


first of apologies such verbose question. :)

i have class parent , class child, parent child onetomany mapping , there reference parent in child. structure follows:

@entity @table (name = "parent_table") class parent {    @id    @column (name = "parent_id")    protected long parentid;     @column (name = "parent_nm")    protected string parentname;     @onetomany (mappedby = "parent")    @column (name = "parent_id")    protected set<child> children;  }  @entity @table (name = "child_table") class child {    @id    @column (name = "child_id")    protected long childid;     @column (name = "child_nm")    protected string childname;     @manytoone    @joincolumn (name = "parent_id", referencedcolumnname = "parent_id")    protected parent parent;     public string tostring() {       return "child [childid=" + childid + ", parentid=" + parent.getparentid() + "]");    } }

i having issue this. whenever load child object using session.load(child.class, 10l) , try print entity object, "assertion failure: null identifier". however, when first load parent objects , load child object, working fine.

scenario fails

child child = (child) session.load(child.class, 10l); system.out.println(child);

scenario works

list<parent> parents = (list<parent>) session.createquery("from parent").list(); child child = (child) session.load(child.class, 10l); system.out.println(child);

the exception stacktrace is:

exception in thread "main" org.hibernate.assertionfailure: null identifier     @ org.hibernate.engine.spi.entitykey.<init>(entitykey.java:69)     @ org.hibernate.internal.abstractsessionimpl.generateentitykey(abstractsessionimpl.java:241)     @ org.hibernate.loader.loader.extractkeysfromresultset(loader.java:722)     @ org.hibernate.loader.loader.getrowfromresultset(loader.java:635)     @ org.hibernate.loader.loader.doquery(loader.java:850)     @ org.hibernate.loader.loader.doqueryandinitializenonlazycollections(loader.java:289)     @ org.hibernate.loader.loader.doqueryandinitializenonlazycollections(loader.java:259)     @ org.hibernate.loader.loader.loadentity(loader.java:2042)     @ org.hibernate.loader.entity.abstractentityloader.load(abstractentityloader.java:82)     @ org.hibernate.loader.entity.abstractentityloader.load(abstractentityloader.java:72)     @ org.hibernate.persister.entity.abstractentitypersister.load(abstractentitypersister.java:3710)     @ org.hibernate.event.internal.defaultloadeventlistener.loadfromdatasource(defaultloadeventlistener.java:439)     @ org.hibernate.event.internal.defaultloadeventlistener.doload(defaultloadeventlistener.java:420)     @ org.hibernate.event.internal.defaultloadeventlistener.load(defaultloadeventlistener.java:204)     @ org.hibernate.event.internal.defaultloadeventlistener.onload(defaultloadeventlistener.java:143)     @ org.hibernate.internal.sessionimpl.fireload(sessionimpl.java:992)     @ org.hibernate.internal.sessionimpl.immediateload(sessionimpl.java:907)     @ org.hibernate.proxy.abstractlazyinitializer.initialize(abstractlazyinitializer.java:158)     @ org.hibernate.proxy.abstractlazyinitializer.getimplementation(abstractlazyinitializer.java:195)     @ org.hibernate.proxy.pojo.javassist.javassistlazyinitializer.invoke(javassistlazyinitializer.java:185)     @ parent_$$_javassist_63.getparentid(parent_$$_javassist_63.java)     @ child.tostring(child.java:110)

when tried analyze issue myself, observed issue because in failure scenario, whenever child.parent being accessed parent object not yet loaded.

is observation right?

how solve issue?


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