Thank you for your answers. I was trying to give input to topic from console. Therefore, when I consume the message on kafka streams, I got values with null keys. When I used producer classes of kafka as a Producer, I managed to solve the problem.
Thank you for your guidance. Adrienne. On Thu, Jun 16, 2016 at 10:57 AM, Matthias J. Sax <matth...@confluent.io> wrote: > On small addition: > > If your input topic does not have any key specified, you can still > extract a key from the value > > KTable source = builder.stream(...).selectKey(...).toTable(...) > > > -Matthias > > On 06/15/2016 08:30 PM, Eno Thereska wrote: > > Hi Adrienne, > > > > How do you enter the input on t1 topic? If using kafka-console-producer, > you'll need to pass in keys as well as values. Here is an example: > http://www.shayne.me/blog/2015/2015-06-25-everything-about-kafka-part-2/ < > http://www.shayne.me/blog/2015/2015-06-25-everything-about-kafka-part-2/> > > > > Thanks > > Eno > > > >> On 15 Jun 2016, at 17:21, Adrienne Kole <adrienneko...@gmail.com> > wrote: > >> > >> Hi community, > >> > >> Probably it is very basic question, as I am new to Kafka Streams. > >> I am trying to initialize KTable or KStream from kafka topic. However, > I > >> don't know how to avoid getting null keys. So, > >> > >> KTable<String, String> source = > >> builder.stream(Serdes.String(),Serdes.String(),"t1"); > >> source.print(); > >> > >> I enter the input on t1 topic as: > >> > >> one > >> two > >> one one > >> > >> and get as a result: > >> > >> null, (one <-null) > >> null, (two <-null) > >> null, (one one <-null) > >> > >> > >> So, the key is always null. > >> > >> Is the key supposed to initialize after getting input from topic? If > yes, > >> how can I initialize key in KTable after getting input? For example in > >> KStream we have KeyValueMapper that can be used to assign new keys and > >> values. However, in KTable we have only ValueMappers. > >> > >> If not, how can I initialize the key of KTable from the input from > given > >> topic? > >> > >> > >> Cheers > >> Adrienne > > > > > >
