how can get count of rows in hibernate when hql have group by?

Question

I have hql query that have group by .In pagination result i want to get count of all result to show in pagination . In query that donot have group by .I write a utility that create count of query from hql query like this

select u 
from Personel u 
where u.lastname='azizkhani'

i find main "from" keyword and substring hql and add count(*) and then make this query

select count(*) 
from Personel u  
where u.lastname='azizkhani'

when i have query that contain group by i can not do it like this

select u.lastname,count(*) 
from Personel u 
group by u.lastname;

count of that query in sql is

select count(*) 
   from (
         select u.lastname,count(*) 
         from tbl_personel u 
         group  by u.lastname
    )

how can i generate group by query from hql ??

I have GenericRepository that have method like this

public <U> PagingResult<U> getAllGrid(String hql,Map<String, Object> params,PagingRequest searchOption);

and developer call that like this

   String hqlQuery = " select e from Personel e where 1<>2 and e.lastname=:lastname";

    HashMap<String, Object> params = new HashMap<String, Object>();
    params.put("lastname", 'azizkhani');


    return getAllGrid(hqlQuery, params, new PagingRequest( 0/*page*/, 10 /*size*/) );

in GenericRepository i will return PagingResult object that have property

public class PagingResult<T> {

    private int totalElements;

    @JsonProperty("rows")
    private List<T> items;

    public PagingResult() {

    }

    public PagingResult(int totalElements, List<T> items) {
        super();
        this.totalElements = totalElements;
        this.items = items;
    }


    public int getTotalElements() {
        return totalElements;
    }

    public void setTotalElements(int totalElements) {
        this.totalElements = totalElements;
    }


    public List<T> getItems() {
        return items;
    }

    public void setItems(List<T> items) {
        this.items = items;
    }

}

In GenericRepository i will execute two query ,first one for get 10 result and second for get totalRecords .Developer just send Hql .I will make hql for get totalcount . for query that dose not have "distinct" or "group by" i make hql .but when hql have "distinct" and "group by" i have problem .

public <U> PagingResult<U> getAllGrid(String hql, Map<String, Object> params, PagingRequest searchOption) {
        Session session = getSession();
        applyDafaultAuthorizeFilter(session);


        Query query = session.createQuery(hql);
        if (searchOption != null) {
            if (searchOption.getSize() > 0) {
                query.setFirstResult(searchOption.getPage() * searchOption.getSize());
                query.setMaxResults(searchOption.getSize());
            }
        }
        if (params != null)
            HQLUtility.setQueryParameters(query, params);

        List<U> list = query.getResultList();

        Query countQuery = session.createQuery("select count(*) " + HQLUtility.retriveCountQueryFromHql(hql));

        if (params != null)
            HQLUtility.setQueryParameters(countQuery, params);

        int count = ((Long) countQuery.uniqueResult()).intValue();
        if (searchOption != null)
            return new PagingResult<U>(searchOption.getPage(), count, searchOption.getSize(), list);
        else
            return new PagingResult<U>(0, count, 0, list);
    }


   public static StringBuffer retriveCountQueryFromHql(StringBuffer jql) {
        if(jql.indexOf("order by")>=0)
            jql.replace(jql.indexOf("order by"), jql.length(),"");
        String mainQuery = jql.toString();

        jql = new StringBuffer(jql.toString().replace('\t', ' '));
        int firstIndexPBas = jql.indexOf(")");
        int firstIndexPBaz = jql.lastIndexOf("(", firstIndexPBas);
        while (firstIndexPBas > 0) {
            for (int i = firstIndexPBaz; i < firstIndexPBas + 1; i++)
                jql.replace(i, i + 1, "*");
            firstIndexPBas = jql.indexOf(")");
            firstIndexPBaz = jql.lastIndexOf("(", firstIndexPBas);
        }
        int Indexfrom = jql.indexOf(" from ");
        return new StringBuffer(" " + mainQuery.substring(Indexfrom, jql.length()));
    }

    public void applyDafaultAuthorizeFilter(Session session) {
        Filter filter = session.enableFilter("defaultFilter");
        filter.setParameter("userId", SecurityUtility.getAuthenticatedUserId());
        filter.setParameter("orgId", SecurityUtility.getAuthenticatedUserOrganization().getId());
    }

how can i solve this problem without change signature of my GenericRepository???

I think i have solution that convert hql to sql and create native query like this select count(*) from ( hql_to_sql) but i have two problem

1. hql to sql dose not have api that support parameter
2. hql to sql dose not have api that support hibernate filter

Answer 1

Why not replace the group by with a count(distinct)?

So instead of

select u from tbl_personel u group by u.lastname

you do

select count(distinct u.lastname) from tbl_personel u