why is the first member of the tuple received from kafka using spark direct stream is null -

-

when reading messages kafka using kafkautils.createdirectstream, v1._1 member of tuple2 null:

kafkautils.createdirectstream(                 streamingcontext,                 string.class,                 string.class,                 stringdecoder.class,                 stringdecoder.class,                 kafkaparams,                 topicsset                 ).map(new function<tuple2<string,string>, string>() {                     @override                     public string call(tuple2<string, string> v1)                             throws exception {                         system.out.println(v1._1);                         return null;                     }                 });

while _2 member contains message passed kafka.

i have 2 questions:

1) why v1._1 null?

2) there way pass topic name in kafka (the same way message put kafka) v1._1 contain topic name?


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