OneToOne how to fetch join data with a transient field ?
Daniel Guryca
I HAVE THESE 2 MODELS:
@Entity
public class Prod extends Model {
@OneToOne(fetch = FetchType.LAZY)
public ProdDetail prodDetail;
@Transient
public String descr;
public Prod() {
super();
this.prodDetail = new ProdDetail();
}
public String getDescr() {
ProdDetail detail = this.prodDetail;
return detail.descr;
}
}
@Entity
public class ProdDetail extends Model {
@Required
public String descr;
public ProdDetail() {
super();
}
}
FIRST CASE:
public static void index() {
Prod prod = Prod.find("").first();
ProdDetail detail = prod.prodDetail;
Logger.info(detail.descr);
}
SECOND CASE:
public static void index2() {
Prod prod = Prod.find("").first();
OR THIS QUERY
Prod prod = Prod.find("select p FROM Prod p JOIN p.prodDetail
pd").first();
ProdDetail detail = prod.prodDetail;
Logger.info(prod.descr); // RETURNS NULL - WHY ??
}
in 1:
It returns the right content of ProdDetail.
In 2:
ProductDetail is set but descr field is null.
Any help is appreciated.
Thanks
Daniel
Nicolas Leroux
Try with .order("asc") on both queries for example?
Nicolas
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Guillaume Bort
Logger.info(prod.getDescr());
Works?
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Daniel Guryca
Daniel
Nicolas Martignole
Just a bit of curiosity : why do you hide the descr attribute with the
Transient getter ?
Else the answer to your question is that if you declare a public
method name "getDescr"
on your Entity Prod, then it cannot be enriched at runtime by
Hibernate to perform the lazy-loading.
Try to rename-it to getMyDescription and it should work.
A simplier and better approach would be to stick to the Active Record pattern.
On your Prod entity, do not hide the "descr" attribute from Prod with
an error-prone getter.
You could rename attribute descr to description on ProdDetail, then
use directly the statement below
on the groovy side in your view.
My product description = ${prod?.prodDetail?.description}
Nicolas
2010/10/4 Guillaume Bort <guillau...@gmail.com>:
Daniel Guryca
Daniel
Daniel Guryca
On Mon, Oct 4, 2010 at 1:41 PM, Nicolas Martignole
<nic...@martignole.net> wrote:
> Hi Daniel
>
> Just a bit of curiosity : why do you hide the descr attribute with the
> Transient getter ?
Because in my real application descr field is a blob which can be even
100kB large. So I want to fetch it lazily via OneToOne.
>
> Else the answer to your question is that if you declare a public
> method name "getDescr"
> on your Entity Prod, then it cannot be enriched at runtime by
> Hibernate to perform the lazy-loading.
> Try to rename-it to getMyDescription and it should work.
>
> A simplier and better approach would be to stick to the Active Record pattern.
>
> On your Prod entity, do not hide the "descr" attribute from Prod with
> an error-prone getter.
> You could rename attribute descr to description on ProdDetail, then
> use directly the statement below
> on the groovy side in your view.
>
> My product description = ${prod?.prodDetail?.description}
Yes I know I can use it this way in groovy but I use these methods in
java since in my real application I have descrDe, descrEn, ... and
descr is just a transient field which calls getDescr() method (because
of nice Play magic).
Guillaume Bort
Daniel Guryca
class models.ProdDetail_$$_javassist_135
Daniel
damian
way of knowing that it is supposed to refer to the "descr" from
Detail. Try adding a @PostLoad'd method to Prod. Eg:
@PostLoad
public void loadDescr() {
this.descr = prodDetail.descr;
}
Or; just refer to getDescr() rather than "descr".
Btw, @OneToOne is not such a great construct for Hibernate as it will
*never* be lazy loaded. You're better to make it @OneToMany and fake
up the single relationship.
Cheers,
Damian.
Daniel Guryca
Even if I completely remove this transient field (since I do not need
it) and check everything only via getDescr() it still does not work.
If I call this.prodDetail in a Prod model I would expect that
prodDetail field will be auto populated since prodDetail is anotated
with @OneToOne.
It's what I do not understand.
Any other idea ?
Thank you
Daniel
Daniel Guryca
I completely removed transient field descr since it's not the core of a problem.
Problem is a descr field in a ProdDetail model and a getDescr() method
in a Prod model.
If I rename descr field in a ProdDetail model to description
everything starts to work as expected.
What the hell is going on ?
If field name (description located in a ProdDetail model) is same with
name of a method located in a Prod model it stops working !!
I really do not uderstand what's wrong. Method is and should be
totally independant of a field which is located in other model.
index and index2 actions should give same result "test".
Just my complete controller + models:
public class Prods extends Controller {
private static Prod createOrGet() {
Prod prod = Prod.find("").first();
if(prod == null) {
Prod p = new Prod();
p.prodDetail.description = "test";
p.save();
prod = Prod.find("").first();
}
return prod;
}
public static void index() {
Prod prod = createOrGet();
ProdDetail detail = prod.prodDetail;
String descr = detail.description;
renderText(descr);
}
public static void index2() {
Prod prod = createOrGet();
String descr = prod.getDescription();
renderText(descr);
}
}
@Entity
public class Prod extends Model {
@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "fk_prodDetail")
public ProdDetail prodDetail;
public Prod() {
super();
this.prodDetail = new ProdDetail();
}
public String getDescription() {
ProdDetail detail = this.prodDetail;
return detail.description;
}
}
@Entity
public class ProdDetail extends Model {
@Required
public String description;
public ProdDetail() {
super();
}
}
NOT WORKING VERSION:
public class Prods extends Controller {
private static Prod createOrGet() {
Prod prod = Prod.find("").first();
if(prod == null) {
Prod p = new Prod();
p.prodDetail.description = "test";
p.save();
prod = Prod.find("").first();
}
return prod;
}
public static void index() {
Prod prod = createOrGet();
ProdDetail detail = prod.prodDetail;
String descr = detail.description;
renderText(descr);
}
public static void index2() {
Prod prod = createOrGet();
String descr = prod.getDescription();
renderText(descr);
}
}
@Entity
public class Prod extends Model {
@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "fk_prodDetail")
public ProdDetail prodDetail;
public Prod() {
super();
this.prodDetail = new ProdDetail();
}
public String getDescription() {
ProdDetail detail = this.prodDetail;
return detail.description;
}
}
@Entity
public class ProdDetail extends Model {
@Required
public String description;
public ProdDetail() {
super();
Daniel Guryca
working version (with just changed method name so that method is not
same to a field name).
A WORKING VERSION:
public class Prods extends Controller {
private static Prod createOrGet() {
Prod prod = Prod.find("").first();
if(prod == null) {
Prod p = new Prod();
p.prodDetail.description = "test";
p.save();
prod = Prod.find("").first();
}
return prod;
}
public static void index() {
Prod prod = createOrGet();
ProdDetail detail = prod.prodDetail;
String descr = detail.description;
renderText(descr);
}
public static void index2() {
Prod prod = createOrGet();
String descr = prod.getDescriptionCHANGED();
renderText(descr);
}
}
@Entity
public class Prod extends Model {
@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "fk_prodDetail")
public ProdDetail prodDetail;
public Prod() {
super();
this.prodDetail = new ProdDetail();
}
public String getDescriptionCHANGED() {
Guillaume Bort
between the bytecode enhancement of Play and the one done by
hibernate. Can you report a bug with your test case?
--
Daniel Guryca
Dunsun
I have been bitten by this bug again.
Daniel
On 5 říj, 17:11, Daniel Guryca <dun...@gmail.com> wrote:
> Ticket created:
>
> http://play.lighthouseapp.com/projects/57987-play-framework/tickets/2...
>
> Thank you
> Daniel
> >>>>> Your @Transient field "descr" is never populated and Hibernate has no
> >>>>> way of knowing that it is supposed to refer to the "descr" from
> >>>>> Detail. Try adding a @PostLoad'd method to Prod. Eg:
>
> >>>>> @PostLoad
> >>>>> public void loadDescr() {
> >>>>> this.descr = prodDetail.descr;
> >>>>> }
>
> >>>>> Or; just refer to getDescr() rather than "descr".
>
>
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