JDBCTemplate RowMapper for Nested POJOs

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JDBCTemplate RowMapper for Nested POJOs

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#1 by (1 votes)

2

Let's say I have the following Pojos

public class Pedidos{
 private Strig codigo;
 private String nomePedido;
 private List<Dados> dadosPedido;
 //getters e setters}  
}

E

  public class Dados {
    private String nome;
    private int codigo;
 }

I know I could use a BeanPropertyRowMapper to populate a list of Orders objects, now is there any way to also populate the Data object through the same query? After that I would need to mount an XML where each Request would have its corresponding Data list, I found a similar question: link
But in my case I also have a List of Users.

java query jdbc spring

asked by anonymous 27.02.2014 / 19:48

1 answer

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score 1 · Accepted Answer

RowMapper is not a good solution for this.

I was here thinking about a gambiarra to store an internal map or something, but searching for an alternative, I found this code almost ready using ResultSetExtractor :

jdbcTemplate.query("SELECT * FROM INVOICE inv JOIN INVOICE_LINE line " +
   + " on inv.id = line.invoice_id", new ResultSetExtractor<List<Invoice>>() {

    List<Invoice> extractData(ResultSet rs) {
        Map<Integer,Invoice> invoices = new HashMap<Integer,Invoice>();
        while(rs.hasNext()) {
            rs.next();
            Integer invoiceId = rs.getInd("inv.id");
            Invoice invoice = invoces.get(invoiceId);
            if (invoice == null) {
               invoice = invoiceRowMapper.mapRow(rs);
               invoices.put(invoiceId,invoice);
            }
            InvoiceItem item = invLineMapper.mapRow(rs);
            invoice.addItem(item);  
        }
        return invoices.values();
    }


});

Font

With ResultSetExtractor you manually iterate over the query results. For each record:

Retrieve id of the object in your main table ( Pedidos )

Verify that Pedido already exists on the map 2.1 If it does not exist, create the product and put it on the map

Retrieve information from table Dados

Add the data to the current product list

The end result is a product map, each with its data filled in. To return a list of products, use the keySet() method of the map.