Re: tapestry-jpa: JpaGridDataSource sort by a transient field

[Richard Yunhua Sang]

Hi Taha,

I have no problem to write a new GridDataSource to do such thing; but as I
said, it would be good to have this function in JPAGridDataSource.

e.g.

@Entity
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String firstName;

    private String lastName;

    public Long getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Transient
    public String getName() {
        return firstName + " " + lastName;
    }

}

The users may want to show name only, and want to sort the list by name
naturally.

Thanks,
Yunhua



On Mon, Jul 11, 2011 at 7:43 PM, Taha Hafeez <tawus.tapes...@gmail.com>wrote:

> Hi Richard,
>
> Internally JPAGridDataSource does not handle sorting itself, instead it
> delegates it to JPA and transient values are unknown to JPA. If you want to
> handle transient values, you will have to write you own implementation of
> GridDataSource where in you can retrieve all the rows from the database and
> based on the SortConstraints passed to prepare() method, sort the values
> yourself.
>
> regards
> Taha
>
> On Tue, Jul 12, 2011 at 4:58 AM, Richard Yunhua Sang
> <yunhua.s...@gmail.com>wrote:
>
> > Thanks for your reply, but I do want to sort the result by transient
> field
> > in Grid. It would be appreciated that the JPAGridDataSource is able to
> sort
> > the result within JVM.
> >
> > On Mon, Jul 11, 2011 at 5:29 PM, Thiago H. de Paula Figueiredo <
> > thiag...@gmail.com> wrote:
> >
> > > On Mon, 11 Jul 2011 18:06:17 -0300, Richard Yunhua Sang <
> > > yunhua.s...@gmail.com> wrote:
> > >
> > >  Hi there,
> > >>
> > >
> > > Hi!
> > >
> > >
> > >  I am using a Grid with JpaGridDataSource; when I click sort icon on a
> > >> transient field of an entity, I get following exception:
> > >>
> > >
> > > I don't think any GridDataSource implementation backed by a database
> > would
> > > be able to handle transient properties, so you should set their
> > > corresponding PropertyModel's as unsortable. To get the PropertyModel,
> > > create a BeanModel for you entity class using the BeanModelSource
> service
> > > and use its get() method.
> > >
> > > --
> > > Thiago H. de Paula Figueiredo
> > > Independent Java, Apache Tapestry 5 and Hibernate consultant,
> developer,
> > > and instructor
> > > Owner, Ars Machina Tecnologia da Informação Ltda.
> > > http://www.arsmachina.com.br
> > >
> >
>