java - Why does EntityManager.merge() prevent LazyInitializationException while EntityManager.find() don't? -


given following situation in web application:

// entitymanager em, 1 per request spring's openentitymanagerinviewfilter // parent oldparent, previous request (and therefore persistence context) parent parent = em.find(parent.class, oldparent.getid()); list<child> children = parent.getchildren(); // mapped collection lazyloading (child child : children) {      ...

the call of list iterator causes lazyinitializationexception. confusing, because fetching of list of children occurs in same persistence context (or wrong?). but, using merge(), works. if 2 request sharing 1 persistence context.

parent parent = em.merge(oldparent); list<child> children = parent.getchildren(); (child child : children) {      ... // no exception!!

what error in reasoning?

addition
i've proven error not caused parent.getid(). part of stacktrace:

at org.hibernate.collection.persistentlist.iterator(persistentlist.java:138)

that means iterator causes problem. , it's getting more weird - i've checked in first case (with find()), select statement issued hibernate retrieve new object database, not cache of persistence context.

addition2
here's bit more stacktrace:

org.hibernate.lazyinitializationexception: failed lazily initialize collection of role: edeka.sw.phb.model.chapter.subchapters, no session or session closed     @ org.hibernate.collection.abstractpersistentcollection.throwlazyinitializationexception(abstractpersistentcollection.java:380)     @ org.hibernate.collection.abstractpersistentcollection.throwlazyinitializationexceptionifnotconnected(abstractpersistentcollection.java:372)     @ org.hibernate.collection.abstractpersistentcollection.initialize(abstractpersistentcollection.java:365)     @ org.hibernate.collection.abstractpersistentcollection.read(abstractpersistentcollection.java:108)     @ org.hibernate.collection.persistentlist.iterator(persistentlist.java:138)     @ java.util.collections$unmodifiablecollection$1.<init>(collections.java:1022)     @ java.util.collections$unmodifiablecollection.iterator(collections.java:1021)     //... followed line of foreach.

i think problem not in iterating part because iterate new loaded parent. problem has .getid() seems not loaded merge works because dont call .getid()


Comments

Post a Comment

Popular posts from this blog

asp.net - repeatedly call AddImageUrl(url) to assemble pdf document -

i'm using abcpdf , i'm curious if can recursively call addimageurl() function assemble pdf document compile multiple urls? something like: int pagecount = 0; int theid = thedoc.addimageurl("http://stackoverflow.com/search?q=abcpdf+footer+page+x+out+of+", true, 0, true); //assemble document while (thedoc.chainable(theid)) { thedoc.page = thedoc.addpage(); theid = thedoc.addimagetochain(theid); } pagecount = thedoc.pagecount; console.writeline("1 document page count:" + pagecount); //flatten document (int = 1; <= pagecount; i++) { thedoc.pagenumber = i; thedoc.flatten(); } //now try again theid = thedoc.addimageurl("http://stackoverflow.com/questions/1980890/pdf-report-generation", true, 0, true); //assemble document while (thedoc.chainable(theid)) { thedoc.page = thedoc.addpage(); theid = thedoc.addimagetoc...
Read more

java - Android recognize cell phone with keyboard or not? -

in android app, want detect user's device if device has keyboard(like motorola milestone) , show corresponding user interface. guys know how that? ! regards justicepenny http://developer.android.com/reference/android/content/res/configuration.html public int keyboard the kind of keyboard attached device. 1 of: keyboard_nokeys, keyboard_qwerty, keyboard_12key. that's it!
Read more

iphone - How would you achieve a LED Scrolling effect? -

how achieve led scrolling effect example below? led sign - led ticker emulator iphone , ipad http://img.skitch.com/20101201-rsfh4p1bajb1wp94k466pdpiuj.preview.jpg sometimes remunerates comment in other posts :) have put code you, should implement font '8pin matrix' realistic feeling. uilabel *label; - (void)viewdidload { [super viewdidload]; label = [[uilabel alloc]initwithframe:cgrectmake(10, 50, 300, 20)]; label.font = [uifont fontwithname:@"courier-bold" size:16.0]; label.backgroundcolor = [uicolor blackcolor]; label.textcolor = [uicolor greencolor]; label.linebreakmode = uilinebreakmodecharacterwrap; // otherwise "…" label.text = @"this led text scrolled "; // blanks space between [self.view addsubview:label]; [nstimer scheduledtimerwithtimeinterval:0.12f target:self selector:@selector(scrolllabel) use...
Read more