Hello, I have a bidirectional association in my model: Product OneToMany Price Price OneToOne Product
When I try to add a new price on a form and then save it I get a StackOverflow error, here is stacktrace from my project:
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at my.model.Ware_$$_jvstd2_b5.submitToOrigin(Ware_$$_jvstd2_b5.java)
at org.zkoss.bind.proxy.BeanProxyHandler.invoke(BeanProxyHandler.java:126)
at my.model.Price_$$_jvstd2_b9.submitToOrigin(Price_$$_jvstd2_b9.java)
at org.zkoss.bind.proxy.AbstractCollectionProxy.submitToOrigin(AbstractCollectionProxy.java:233)
at org.zkoss.bind.proxy.BeanProxyHandler.invoke(BeanProxyHandler.java:126)
at org.zkoss.bind.proxy.FormProxyHandler.invoke(FormProxyHandler.java:163)
at my.model.Ware_$$_jvstd2_b5.submitToOrigin(Ware_$$_jvstd2_b5.java)
at org.zkoss.bind.proxy.BeanProxyHandler.invoke(BeanProxyHandler.java:126)
at my.model.Price_$$_jvstd2_b9.submitToOrigin(Price_$$_jvstd2_b9.java)
at org.zkoss.bind.proxy.AbstractCollectionProxy.submitToOrigin(AbstractCollectionProxy.java:233)
Here is a quick fiddle to reproduce this error: https://zkfiddle.org/sample/h7t36l/1-Another-new-ZK-fiddle
Press "Add price" button and then "Save".
Some explanations: In class Logic.java on 25 and 26 strings you'll find
price = product.getPrices().stream().findFirst().get();
price.setProduct(product);
I do this to get a proxied instance of Price, if I keep using an original object, then I get a Hibernate error, that my instance is transient and can't be saved.
In debug mode I see that after submitting all values to original price still contains proxied object of Ware (Product).
If I put an original ware object to original price object, then I get another one proxy instance of ware in price.
Any ideas?
Hi there.
This structure will generate an infinite loop of cascading proxy objects. A product has a collection of prices, which in turn refer to the product, which refer to the price, etc.
You have to choose a point at which to use the actual object instead of a proxy. For example, you can decide that the proxy object targets "real" price objects instead of proxy prices. You can use the @immutable and @immutableelements annotations to do so.
http://books.zkoss.org/zk-mvvm-book/8.0/syntax/immutable.html
http://books.zkoss.org/zk-mvvm-book/8.0/syntax/immutableelements.html
See an example in fiddle. https://zkfiddle.org/sample/h7t36l/10-Another-new-ZK-fiddle
Hi MDuchemin, I understand why this happens. The problem is that I have Maven multimodule with my entities in backend and ZK in front. Also, I guess that price.getProduct() will also return a non-proxied object which will show no changes before saving. In that case it breaks the logic
pavelEW ( 2021-03-07 04:16:14 +0800 )editAsked: 2021-03-04 17:57:55 +0800
Seen: 9 times
Last updated: Mar 05 '21
