avro2ddl.clj

(ns cddr.avro2ddl
  (:require
   [clojure.string :as string]
   [clojure.java.io :as io]
   [clojure.data.json :as json])
  (:gen-class))

(def home (System/getProperty "user.home"))

(def loan (-> (format "%s/Projects/avro-schemas/schemas/loan-3.json"
                      home)
              slurp
              json/read-str))

(defn optional?
  [t]
  (and (vector? t)
       (= "null" (first t))))

(defn enum?
  [t]
  (and (map? t)
       (= "enum" (get t "type"))))

(def type-map
  {"string" "text"
   "double" "double precision"
   "long" "integer"
   "int" "integer"})

(defn supported?
  [t]
  (contains? #{"string" "long" "int"} t))

(defn column-for
  [{:strs [name type default]}]
  (cond
    (type-map type) {:name name
                     :type (get type-map type)}
    (optional? type) {:name name
                      :type (second type)
                      :nullable? true
                      :default default}
    (enum? type)     {:name name
                      :type "text"}))

(defn table-for
  [{:strs [type name fields]}]
  {:name name
   :columns (map column-for fields)})

(defn format-column
  [column]
  (with-out-str
    (print "  ")
    (pr (:name column))
    (print (format " %s" (:type column)))
    (when-not (:nullable? column)
      (print " not null"))
    (when-let [default (:default column)]
      (print (format " default %s" default)))))


(defn format-table
  [table]
  (format "
create table %s (
%s
);
"
          (:name table)
          (string/join ",\n" (map format-column (:columns table)))))

(-> (table-for loan)
    format-table
    print)