使用标准

Question

我有一个类项目和类别

Class Item 
{ 
    private long ItemId; 
    private String ItemName; 
    private String ItemDescription; 
    private String ItemWebSite; 
    private String Condition; 
    private long Price; 
    private String Brand; 
    private String AttributeDescription; 
    private Category ProductCategory; 
    private Set <Picture> Pictures= new HashSet <Picture>(); 
    //getters and setters 
} 

Class Category 
{ 
     private long CategoryId; 
    private String CategoryName; 
    private Category ParentCategory; 
    private Set <Category> SubCategory=new HashSet <Category>(); 
    private Set <Attribute> AllAttributes= new HashSet <Attribute>(); 
     //getters and setters 
} 

时，遇到了休眠错误，但在我做follwing查询：

long id=841; 

Criteria crit =session.createCriteria(Item.class).add(Restrictions.eq("ProductCategory",id)); 

我收到此错误：

Caused by: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.BiddingSystem.Models.Category.CategoryId 
    at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:198) 
    at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:230) 
    at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:3852) 
    at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:3560) 
    at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:204) 
    at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:243) 
    at org.hibernate.type.EntityType.getIdentifier(EntityType.java:449) 
    at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:141) 
    at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1769) 
    at org.hibernate.loader.Loader.bindParameterValues(Loader.java:1740) 
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1612) 
    at org.hibernate.loader.Loader.doQuery(Loader.java:717) 
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270) 
    at org.hibernate.loader.Loader.doList(Loader.java:2294) 
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172) 
    at org.hibernate.loader.Loader.list(Loader.java:2167) 
    at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119) 
    at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1706) 
    at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347) 
    at com.BiddingSystem.server.ServiceImpl.UpdateCategory(ServiceImpl.java:799) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
    at java.lang.reflect.Method.invoke(Method.java:597) 
    at net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174) 
    ... 21 more 

Answer 1

使用这个：

Criteria crit =session.createCriteria(Item.class).add(Restrictions.eq("ProductCategory.CategoryId",id));