I have this strange behavior with Hibernate SQLQuery.list() method.

Following is the description of the issue:

I have a sql select query which retrieves only single column(group) from the database (i.e., select group from peopleGroup where groupid = 10) And i'm recieving the result of the above list in List of Object array
i.e,

SQLQuery hQuery = session.createSQLQuery("select group from peopleGroup where groupid = 10");
List<Object[]> result = (List<Object[]>)hQuery.list();

Ideally, the result should contain a list of object arrays but when I inspect, 0'th index of the result contains String object instead of an Object array.
However if I use more than one column let's say 2 columns in the select clause of the query I was able to see that 0'th index of the result as Object array i.e., Object[2]={"group","groupid"};

How do I get the Object array even if I have only one column mentioned in the select clause of the query?

1

3 Answers

Docs states:

List list()

Return the query results as a List. If the query contains multiple results per row, the results are returned in an instance of Object[].

Convert it by yourself, like so.

List<Object[]> l = new ArrayList<>();
for(Object o : query.list()) { Object[] arr = {o}; l.add(arr);
}

2

you can create a object mapper like below code

public class QueryMapper { private String group; //setter and getter }

And you have to change your code like below

SQLQuery hQuery = session.createSQLQuery("select group from peopleGroup where groupid = 10");
List<Object[]> result = (List<Object[]>)hQuery.list();
List<QueryMapper> list = new ArrayList<QueryMapper>(); for(Object[] object: result){ QueryMapper queryMapper = new QueryMapper(); if(object[0]!=null){ queryMapper.setGroup((String)object[2]); } list.add(queryMapper); }

All i wanted is to fix the ClassCastException which was caught during the assignment of result.get(0) to the container i.e., container = result.get(0);

Since the value returned by mentioned list() method contains object in case of single column in the select clause of the query and i won't be allowed to cast from certain object to Object[](Object array). Instead i have tried a work around like below

Already existing code

SQLQuery hQuery = session.createSQLQuery("select group from peopleGroup where groupid = 10");
List<Object[]> result = (List<Object[]>)hQuery.list();
Object[] container = result.get(0);

now i have put condition like below to decide how to assign value to the Object[]

SQLQuery hQuery = session.createSQLQuery("select group from peopleGroup where groupid = 10");
List<Object[]> result = (List<Object[]>)hQuery.list();
Object[] container = null;
if(result.get(0) instanceof Object[]) container = result.get(0);
else { container = new Object[1]; container[0] = result.get(0); }

The above solution seems working in my case !

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