Jpa named query: how to get a list of column

Question

I have an entity orderdetails, where a user can have many ordernames I want to get all the ordername by userid using jpa named query. I tried this

SELECT o.orderName FROM OrderDetails o WHERE o.userId=:userId;

Since the return type will be List in the resultset, I executed the query like this

getEntityManager().createNamedQuery("getOrderNamesByUserId", 
orderDetail.class).setParameter("userId", userId);

This obviously is not working. How can I get that query working? One way is to iterate the List but I wonder whether there is another way around?

Jacob · Answer 1 · 2014-06-10T05:18:20.690

0

Well this is non-compiled code snippet, you could try the following approach.

@Override
public List<OrderDetails> findOrders(Long userId) {
        TypedQuery<OrderDetails> query = entityManager.createNamedQuery(
                "OrderDetails.getOrderNamesByUserId", OrderDetails.class);
        query.setParameter("userId", userId);
        List<OrderDetails> list = query.getResultList();
        return list;
    }

edited Jun 10 '14 at 05:18

answered Jun 10 '14 at 05:13

Jacob

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yes, this is obvious, but I need is List (list of ordernames), not the list of type orderdetails (not List – Maverick Jun 10 '14 at 12:16
@user3706166 Once you have in list, then you could retrieve using `toString()` method. – Jacob Jun 10 '14 at 12:17
yes, I was wondering if there is any way to get the result on the fly..! just like normal query. – Maverick Jun 11 '14 at 04:36
@user3706166 I didn't quite understand _result on the fly..! just like normal query_ – Jacob Jun 11 '14 at 05:22

score 0 · Answer 2 · answered Jun 10 '14 at 07:35

0

If you just need to select one column(ordername), use getResultList() method.

    Query query = getEntityManager().createNamedQuery("getOrderNamesByUserId", OrderDetail.class);
    query.setParameter("userId", userId);
    List<String> orderNameList = query.getResultList();

answered Jun 10 '14 at 07:35

Zaw Than oo

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We cannot do this. Because, query.getResultList() returns a resultlist of type List. – Maverick Jun 10 '14 at 12:14
Check your query `SELECT o.orderName ..`. It is return a list of `OrderDetail`?. – Zaw Than oo Jun 11 '14 at 03:34

Jpa named query: how to get a list of column

2 Answers2