`logicalType` support

[lukaszkorecki]

Hi! Thank you for the library, it's terribly useful (finally we can stop using JSON ;-))

I was wondering if logicalType property is supported - https://avro.apache.org/docs/1.8.0/spec.html#Logical+Types

From my quick experiments it looks like they don't work, or I'm simply doing something wrong:

(require '[abracad.avro :as avro])

(def schema
  (avro/parse-schema
   {:type :record
    :name "Thing"
    :fields [{:name "name", :type :string}
             {:name "timestamp" :logicalType "date" :type :int}]}))

(def ex
  { :name "Foo" :timestamp 1491306685 })

(->> (avro/binary-encoded schema ex)
     (avro/decode schema))

;; => {:name "Foo", :timestamp 1491306685}

if it's not supported, I'm happy to add support but I'd need a bit of help as to where should I start 👍

Thanks!

[llasram]

It is not currently supported -- logicalType post-dates the original implementation and just hasn't been added. So a PR would be great! I'd suggest trying to extend the existing "Avro readers" system for custom decoding of records to use the value of logicalType for custom decoding of non-record types as well, although the extra annotations described for the "decimal" type do complicate matters.

[lukaszkorecki]

@llasram Awesome, thanks for the pointer. No promises about the time, but I will definitely set aside some time to work on this.

[gleisonsilva]

@lukaszkorecki Hello! Have you get along with "date" types already? I'm currently facing the need to serialize a Date value, but I'm not figuring out how to do that.

[lukaszkorecki]

@gleisonsilva Hi! Unfortunately, I haven't - so far we've been delegating that to the application logic. We have a set of helper functions in our tiny Abracad wrapper which preprocesses/postprocesses timestamp fields when serializing/deserializing. We use unix timestamps everywhere and UTC as the timezone.
Now - our Avro usage is increasing (we've recently open-sourced our RabbitMQ framework https://github.com/nomnom-insights/nomnom.bunnicula which supports custom serializers/deserializers for publishers and consumers) so we will have to eventually tackle the timestamp serialization issue :-)