Metabase MBQL Driver (demo)

mbql.clj

(ns metabase.driver.mbql
  (:require [cheshire.core :as json]
            [metabase.driver :as driver]
            [metabase.driver.sql-jdbc.connection :as sql-jdbc.conn]
            [metabase.mbql.normalize :as normalize]
            [metabase.models :refer [Database]]
            [metabase.query-processor :as qp]
            [metabase.query-processor.store :as qp.store]
            [toucan.db :as db]))

(driver/register! :mbql, :parent :h2)

(defmethod driver/connection-properties :mbql
  [_]
  [])

(defmethod driver/can-connect? :mbql
  [_ _]
  true)

(defmethod sql-jdbc.conn/connection-details->spec :mbql
  [_ details-map]
  (sql-jdbc.conn/connection-details->spec :h2 (db/select-one-field :details Database :engine "h2", :name "Sample Dataset")))

(defmethod driver/mbql->native :mbql
  [_ query]
  query)

(defmethod driver/execute-reducible-query :mbql
  [_ query context respond]
  (let [mbql (-> query
                 :native
                 :query
                 (json/parse-string true)
                 normalize/normalize)]
    (println "MBQL =>" (pr-str mbql))
    (qp.store/with-store
      (let [mbql      (qp/query->preprocessed mbql)
            sql-query (sql.qp/mbql->native :h2 mbql)]
        (println "sql-query:" (:query sql-query))
        (sql-jdbc.execute/execute-reducible-query :h2 {:native sql-query} context respond)))))