hibernate - Properly cascading this @OneToMany relationship (Spring Data JPA) -

-

alright, i'm little deperate right now. i've read many of other related questions hasn't helped me resolve issue yet. i'll glad if can me out.

i'm using spring data jpa , have these 2 entities:

device.class

private string id;  @onetomany(mappedby = "device", cascade = cascadetype.all) @jsonignore @restresource(exported = false) private list<reading> readings;

reading.class

@manytoone(cascade = {cascadetype.merge}) /*this isn't right...*/ @joincolumn(name = "device_id") private device device;

expectation

i'm saving readings , expect device cascaded correctly (persisted or merged), depending on whether exists. (readings inserted once, never updated)

reality

i can make work partially:

when use cascade = cascadetype.all or cascade = cascadetype.persist can save first reading , mapped device. once insert second reading has relationship same device, along lines of: 

duplicate entry '457129' key 'primary' ('457129' = reading.device.id)

as understand, second reading entity tries cascade device inserting new row instead of updating existing one.

i can "work around" using cascade = cascadetype.merge instead. device updated correctly when save new reading existing device entity. but can no longer cascade device doesn't yet exist!

column 'device_id' cannot null  (reading.device_id)

the save

i receive json dto's , create entities it.

pseudocode:

reading reading = deserialize(jsonreading); device device = deserialize(device);  reading.setdevice(device); /* device entity detached */  readingservice.save(reading);

i guess part of problem might have me setting detached entity?

what doing wrong? realtionships bad? happening? need manage these transactions manually?

thank you!

the @onetomany association definition parent association, if it’s unidirectional or bidirectional one. parent side of association makes sense cascade entity state transitions children. (source: hibernate docs).

based on documentation remove cascade device field. docs contains code examples storing phone , person @onetomany , @manytoone may try.

as didn't post code saving part suppose set device before saving reading as

reading.setdevice(device); readingdao.save(reading); // depends on implementation

when persisting reading object device should saved automatically.


Comments

Post a Comment

Popular posts from this blog

ios - Memory not freeing up after popping viewcontroller using ARC -

-
hi project arc based, using uinavigationcontroller make transition between viewcontroller. using profiler analyse happening behind scene memory. noticed when push viewcontroller allocate memory components , when pop not freeing allocated memory. since using arc unable implement dealloc or release component. have analysed in detail , there no memory leak in project. i not using strong property push viewcontroller. here how pushing viewcontroller. viewcontroller *obj = [[viewcontroller alloc] init]; [self.navigationcontroller pushviewcontroller:obj animated:no]; any clue whats going on? should free memory have consumed. please advise your description indicates have retain cycle, leads objects not being deallocated. typical source of retain cycles properties assigned loading nib files (usually declared iboutlet ). two strategies break them , release objects: declare property weak : @property (nonatomic, weak) iboutlet uilabel *statuslabel; set property nil in...
Read more

Django REST Framework perform_create: You cannot call `.save()` after accessing `serializer.data` -

-
i have following viewset: class artistprofileviewset(viewsets.modelviewset): queryset = artistprofile.objects.all() serializer_class = artistprofileserializer def perform_create(self, serializer): if serializer.is_valid(): serializer.save() with following serializers: class simpleartisttrackserializer(serializers.hyperlinkedmodelserializer): class meta: model = artisttrack fields = (...my fields...) class artistprofileserializer(serializers.hyperlinkedmodelserializer): owners = userserializer(many=true, required=false) tracks = simpleartisttrackserializer(many=true, required=false) class meta: model = artistprofile fields = (...my fields...) i getting following error: assertionerror: cannot call `.save()` after accessing `serializer.data`.if need access data before committing database inspect 'serializer.validated_data' instead. i don't see editing serializer.data object. th...
Read more

Why does Go error when trying to marshal this JSON? -

-
i'm trying rather simple example of trying decode json file structs using golang. however, when attempting error that json: cannot unmarshal object go value of type []main.track which don't understand. here's code in question, , json can found here . package main import ( "encoding/json" "fmt" "net/http" "os" ) // tracks group of track types type tracks struct { tracks []track } // track represents singular track type track struct { name string url string artist artist } // artist represents single artist type artist struct { name string mbid string url string } func main() { url := "http://ws.audioscrobbler.com/2.0/?method=geo.gettoptracks&api_key=c1572082105bd40d247836b5c1819623&format=json&country=netherlands" response, err := http.get(url) if err != nil { fmt.printf("%s\n", err) os.exit(1) } de...
Read more