Custom record reader handler request

[FerdiKuehne]

Good Day Mister!
Currently i write a clojurescript record serialization for fressian.

• https://github.com/FerdiKuehne/incognito

I already implemented custom write-handlers with the help of your fress library.
Now i'm stuck with custom read handlers. It would be great if it is possible to override the default record reader like the record write-handler.

Sincerely Ferdi!

[pkpkpk]

Try master. should be fn<rdr,tag, field-count,name->map-ctor>

[pkpkpk]

can probably get rid of the name->map-ctor arg

[FerdiKuehne]

yeah without name->map-ctor arg would be awesome. And also if the record is not match could it be possible to return an custom object like your taggedObject?

[pkpkpk]

Can you explain your use case alittle bit for me? Are you trying to instantiate stuff before calling the record constructor? If so it may be better to read/write as custom types rather than records

[FerdiKuehne]

Good morning!
Sorry for the delayed response.
Best way to explain the case is with the following code:

  (defrecord IncognitoTaggedLiteral [tag value])

  (defn incognito-write-handlers [write-handlers]
    {"record" (fn [w rec]
                (let [{:keys [tag] :as r} (if (isa? (type rec) incognito.base.IncognitoTaggedLiteral)
                                            (into {} rec)
                                            (incognito-writer @write-handlers rec))]
                  (write-tag w "record" 2)
                  (write-object w (str tag))
                  (write-tag w "map" 1)
                  (beginClosedList w)
                  (doseq [[field value] r]
                    (write-object w field true)
                    (write-object w value))
                  (endList w)))})

  (defn incognito-reader [read-handlers m]
    (if (read-handlers (:tag m))
      ((read-handlers (:tag m)) (:value m))
      (map->IncognitoTaggedLiteral m)))

  (defn incognito-read-handlers [read-handlers]
    {"record" (fn [rdr tag _]
                (let [tag   (read-object rdr)
                      value (read-object rdr)]
                  (incognito-reader @read-handlers
                                    {:tag tag :value val})))})

  (defrecord SomeRecord [f1 f2])
  (def rec (SomeRecord. "field1" "field2"))
  (def buf (fress.api/byte-stream))
  (def writer (fress.api/create-writer buf :handlers (incognito-write-handlers (atom {'incognito.fressian.SomeRecord (fn [foo] (println "foos") (assoc foo :c "donkey"))}))))
  (fress.api/write-object writer rec)
  (fress.api/read buf :handlers (incognito-read-handlers (atom {})))
  ;read returns  => #fress.reader.TaggedObject{:tag "record", :value #js ["incognito.fressian/SomeRecord" {:value {:f1 "field1", :c "donkey", :f2 "field2"}, :tag incognito.fressian/SomeRecord}]}


  ;it should return => #incognito.base.IncognitoTaggedLiteral{:tag incognito.fressian/SomeRecord, :value {:f1 "field1", :c "donkey", :f2 "field2"}}

The custom read-handler for "record" is somehow ignored. Sorry for the confusion. I hope the answer can help.

Best Regards F

[pkpkpk]

I had it set to look for :record, you are right it should have been a string

[FerdiKuehne]

Big thanks! Well done!
It's working! I think the issue can be closed.

Best Regards F