python - Django deleting a model instance with no more related ForeignKey items in another model? -

-

in model below, when artist deleted through admin, it'll confirm , delete related songs. however, when delete song through admin, i'd delete artist if artist has no more related items in song. there model option in admin?

how should done in custom view not inside of modeladmin?

class artist (models.model):     name = models.charfield(max_length=100)      def __str__(self):         return self.name  class genre (models.model):     name = models.charfield(max_length=100)     def __str__(self):         return self.name  class song (models.model):         artist = models.foreignkey(artist, on_delete=models.cascade)     genre = models.foreignkey(genre, null=true, blank=true, on_delete=models.set_null)     title = models.charfield(max_length=100)     mix = models.charfield(max_length=100, blank=true)      def __str__(self):         return self.title

could through delete method of song.

def delete(*args, **kwargs): artist = self.artist super(song, self).delete(*args, **kwargs) if artist.song_set.count() == 0: artist.delete()

or similar.


Comments

Post a Comment

Popular posts from this blog

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