JPA Cannot join to attribute of basic type

Question

    log.debug("get category list start "+id);       
    List<CategoryResponseView> usersViewList = new ArrayList<CategoryResponseView>();
    long a=System.currentTimeMillis(); 

    CriteriaBuilder builder = em.getCriteriaBuilder();
    Metamodel  metamodel=em.getMetamodel();
    EntityType EntrepreneurCategory_=metamodel.entity(EntrepreneurCategory.class);
    CriteriaQuery<Object[]> query = builder.createQuery(Object[].class);

    Root<EntrepreneurCategory> entrepreneurCategoryRoot=query.from(EntrepreneurCategory.class);


    Join<EntrepreneurCategory, Category> categoryJoin = entrepreneurCategoryRoot.join("category_id",JoinType.LEFT);
    Join<EntrepreneurCategory, Cluster> clusterJoin = entrepreneurCategoryRoot.join("cluster_id",JoinType.LEFT);

    List<Predicate> conditions = new ArrayList();
    conditions.add(builder.equal(entrepreneurCategoryRoot.get("id"), id));

    TypedQuery<Object[]> typedQuery = em.createQuery(query
            .multiselect(entrepreneurCategoryRoot).where(conditions.toArray(new Predicate[] {}))                          
    );

    return usersViewList;

org.hibernate.ejb.criteria.BasicPathUsageException: Cannot join to attribute of basic type at org.hibernate.ejb.criteria.path.AbstractFromImpl.constructJoin(AbstractFromImpl.java:262) at org.hibernate.ejb.criteria.path.AbstractFromImpl.join(AbstractFromImpl.java:255) at org.hibernate.ejb.criteria.path.AbstractFromImpl.join(AbstractFromImpl.java:428) at com.vs.manifesto.logic.EntrepreneurCategoryBDL.getCategoryList(EntrepreneurCategoryBDL.java:55) at com.vs.manifesto.scoreboard.services.CategoryServices.getCategoryList(CategoryServices.java:44)

Following is the model class elements

@ManyToOne
@JoinColumn(name = "category_id",referencedColumnName="id",insertable=false,updatable=false)
private Category  category;

private String category_id;

public Category getCategory() {
    return category;
}

public void setCategory(Category category) {
    this.category = category;
}

how to resolve this problem..?

Answer 1

You are joined to attribute of basic type because you are join String "category_id"

"Join<EntrepreneurCategory, Category> categoryJoin = entrepreneurCategoryRoot.join("category_id",JoinType.LEFT);"

You need to change to join to a category like:

"Join<EntrepreneurCategory, Category> categoryJoin = entrepreneurCategoryRoot.join("category",JoinType.LEFT);"