What would be a correct implemantation of JSF Converter if I need to get an Integer to run a query? (should I use another interface)

Question

HI here's my code:

List.xhmtl

<h:selectOneMenu value="#{produtosController.items}">
    <f:selectItems value="#{produtosController.itemsAvailableSelectOne}"/>
</h:selectOneMenu>
<h:commandButton action="#{produtosController.createByCodigos}" value="Buscar" />

My Controller Class with innner Converter implemantation

@ManagedBean (name="produtosController")
@SessionScoped
public class ProdutosController {

    private Produtos current;
    private DataModel items = null;
    @EJB private controladores.ProdutosFacade ejbFacade;
    private PaginationHelper pagination;
    private int selectedItemIndex;

    public ProdutosController() {
    }

    public Produtos getSelected() {
        if (current == null) {
            current = new Produtos();
            selectedItemIndex = -1;
        }
        return current;
    }

    private ProdutosFacade getFacade() {
        return ejbFacade;
    }

    public PaginationHelper getPagination() {
        if (pagination == null) {
            pagination = new PaginationHelper(10) {

                @Override
                public int getItemsCount() {
                    return getFacade().count();
                }

                @Override
                public DataModel createPageDataModel() {
                    return new ListDataModel(getFacade().findRange(new int[]{getPageFirstItem(), getPageFirstItem()+getPageSize()}));
                }
            };
        }
        return pagination;
    }

    public String prepareList() {
        recreateModel();
        return "List";
    }

    public String prepareView() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "View";
    }

    public String prepareCreate() {
        current = new Produtos();
        selectedItemIndex = -1;
        return "Create";
    }

    public String create() {
        try {
            getFacade().create(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosCreated"));
            return prepareCreate();
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }
    public String createByMarcas() {
        items = new ListDataModel(ejbFacade.findByMarcas(current.getIdMarca()));
        updateCurrentItem();
        return "List";
    }

    public String createByModelos() {
        items = new ListDataModel(ejbFacade.findByModelos(current.getIdModelo()));
        updateCurrentItem();
        return "List";
    }

    public String createByCodigos(){
        items = new ListDataModel(ejbFacade.findByCodigo(current.getCodigo()));
        updateCurrentItem();
        return "List";
    }

    public String prepareEdit() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        return "Edit";
    }

    public String update() {
        try {
            getFacade().edit(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosUpdated"));
            return "View";
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
            return null;
        }
    }

    public String destroy() {
        current = (Produtos)getItems().getRowData();
        selectedItemIndex = pagination.getPageFirstItem() + getItems().getRowIndex();
        performDestroy();
        recreateModel();
        return "List";
    }

    public String destroyAndView() {
        performDestroy();
        recreateModel();
        updateCurrentItem();
        if (selectedItemIndex >= 0) {
            return "View";
        } else {
            // all items were removed - go back to list
            recreateModel();
            return "List";
        }
    }

    private void performDestroy() {
        try {
            getFacade().remove(current);
            JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("ProdutosDeleted"));
        } catch (Exception e) {
            JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));
        }
    }

    private void updateCurrentItem() {
        int count = getFacade().count();
        if (selectedItemIndex >= count) {
            // selected index cannot be bigger than number of items:
            selectedItemIndex = count-1;
            // go to previous page if last page disappeared:
            if (pagination.getPageFirstItem() >= count) {
                pagination.previousPage();
            }
        }
        if (selectedItemIndex >= 0) {
            current = getFacade().findRange(new int[]{selectedItemIndex, selectedItemIndex+1}).get(0);
        }
    }

    public DataModel getItems() {
        if (items == null) {
            items = getPagination().createPageDataModel();
        }
        return items;
    }

    private void recreateModel() {
        items = null;
    }

    public String next() {
        getPagination().nextPage();
        recreateModel();
        return "List";
    }

    public String previous() {
        getPagination().previousPage();
        recreateModel();
        return "List";
    }

    public SelectItem[] getItemsAvailableSelectMany() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), false);
    }

    public SelectItem[] getItemsAvailableSelectOne() {
        return JsfUtil.getSelectItems(ejbFacade.findAll(), true);
    }

    @FacesConverter(forClass=Produtos.class)
    public static class ProdutosControllerConverter  implements Converter{

        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            ProdutosController controller = (ProdutosController)facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "produtosController");
            return controller.ejbFacade.find(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.decode(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuffer sb = new StringBuffer();
            sb.append(value);
            return sb.toString();
        }

        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Produtos) {
                Produtos o = (Produtos) object;
                return getStringKey(o.getCodigo());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: "+ProdutosController.class.getName());
            }
        }

    }

}

and my EJB

@Entity
@ViewScoped
@Table(name = "produtos")
@NamedQueries({
    @NamedQuery(name = "Produtos.findAll", query = "SELECT p FROM Produtos p"),
    @NamedQuery(name = "Produtos.findById", query = "SELECT p FROM Produtos p WHERE p.id = :id"),
    @NamedQuery(name = "Produtos.findByCodigo", query = "SELECT p FROM Produtos p WHERE p.codigo = :codigo"),
    @NamedQuery(name = "Produtos.findByDescripcion", query = "SELECT p FROM Produtos p WHERE p.descripcion = :descripcion"),
    @NamedQuery(name = "Produtos.findByImagen", query = "SELECT p FROM Produtos p WHERE p.imagen = :imagen"),
    @NamedQuery(name = "Produtos.findByMarcas", query="SELECT m FROM Produtos m WHERE m.idMarca.id = :idMarca"),
    @NamedQuery(name = "Produtos.findByModelos", query="SELECT m FROM Produtos m WHERE m.idModelo.id = :idModelo")})
public class Produtos implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Column(name = "codigo")
    private Integer codigo;
    @Column(name = "descripcion")
    private String descripcion;
    @Column(name = "imagen")
    private String imagen;
    @JoinColumn(name = "id_modelo", referencedColumnName = "id")
    @ManyToOne(optional = false)
    private Modelos idModelo;
    @JoinColumn(name = "id_marca", referencedColumnName = "id")
    @ManyToOne(optional = false)
    private Marcas idMarca;

    public Produtos() {
    }

    public Produtos(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getCodigo() {
        return codigo;
    }

    public void setCodigo(Integer codigo) {
        this.codigo = codigo;
    }

    public String getDescripcion() {
        return descripcion;
    }

    public void setDescripcion(String descripcion) {
        this.descripcion = descripcion;
    }

    public String getImagen() {
        return imagen;
    }

    public void setImagen(String imagen) {
        this.imagen = imagen;
    }

    public Modelos getIdModelo() {
        return idModelo;
    }

    public void setIdModelo(Modelos idModelo) {
        this.idModelo = idModelo;
    }

    public Marcas getIdMarca() {
        return idMarca;
    }

    public void setIdMarca(Marcas idMarca) {
        this.idMarca = idMarca;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // TODO: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Produtos)) {
            return false;
        }
        Produtos other = (Produtos) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "" + codigo + "";
    }
}

Answer 1

Sorry, I didn't pay close attention to your code. Too much (at-first-glance) irrelevant code and several too localized names which only makes things confusing. At least one of your major mistakes is that you used DataModel instead of the actual Product as item value. This makes no sense.

Here's a kickoff example how the code should look like to get non-standard types in dropdowns to work flawlessly.

XHTML:

<h:form>
    <h:selectOneMenu value="#{bean.selectedProduct}">
        <f:selectItems value="#{bean.selectProducts}" />
    </h:selectOneMenu>
    <h:commandButton value="Submit" action="#{bean.submit}" />
</h:form>

Bean:

private Product selectedProduct; // +getter+setter
private List<SelectItem> selectProducts; // +getter

public Bean() {
    selectProducts = new ArrayList<SelectItem>();
    for (Product product : ejb.list()) {
        selectProducts.add(new SelectItem(product, product.getDescription()));
    }
}

public void submit() {
    System.out.println("Selected product: " + selectedProduct.getDescription());
}

ProductConverter:

public Object getAsObject(FacesContext context, UIComponent component, String value) {
    // Convert String to Integer and find Product by Integer ID.
    return ejb.find(Integer.valueOf(value));
}

public String getAsString(FacesContext context, UIComponent component, Object value) {
    // Convert Integer ID to String.
    return String.valueOf(((Product) value).getId());
}

---

Alternatively, you can also use the f:selectItems with new JSF 2.0 var attribute so that you don't need to convert List<Product> from EJB to List<SelectItem>:

XHTML:

<h:form>
    <h:selectOneMenu value="#{bean.selectedProduct}">
        <f:selectItems value="#{bean.selectProducts}" var="product" 
            itemValue="#{product}" itemLabel="#{product.description}" />
    </h:selectOneMenu>
    <h:commandButton value="Submit" action="#{bean.submit}" />
</h:form>

Bean:

private Product selectedProduct; // +getter+setter
private List<Product> selectProducts; // +getter

public Bean() {
    selectProducts = ejb.list();
}

public void submit() {
    System.out.println("Selected product: " + selectedProduct.getDescription());
}

This still requires the same ProductConverter.

---

See also:

• Using objects in h:selectOneMenu