Add support for DISTINCT ON

deps.edn

@@ -1 +1 @@
-{:deps {honeysql {:mvn/version "0.9.4" :exclusions [org.clojure/clojurescript]}}}
+{:deps {honeysql {:mvn/version "0.9.5" :exclusions [org.clojure/clojurescript]}}}

src/honeysql_postgres/format.cljc

@@ -1,6 +1,6 @@
 (ns ^{:doc "Extension of the honeysql format functions specifically for postgreSQL"}
     honeysql-postgres.format
-  (:require [honeysql.format :as sqlf :refer [fn-handler format-clause]] ;; multi-methods
+  (:require [honeysql.format :as sqlf :refer [fn-handler format-clause format-modifiers]] ;; multi-methods
             [honeysql-postgres.util :as util]
             [clojure.string :as string]))
 
@@ -220,3 +220,6 @@
     (string/join " EXCEPT ALL " (map sqlf/to-sql maps))))
 
 (override-default-clause-priority)
+
+(defmethod format-modifiers :distinct-on [[_ & fields]]
+  (str "DISTINCT ON(" (sqlf/comma-join (map sqlf/to-sql fields)) ")"))

test/honeysql_postgres/postgres_test.cljc

@@ -8,7 +8,8 @@
                                                          create-table rename-table drop-table
                                                          window create-view over with-columns]]
             [honeysql.helpers :as sqlh :refer [insert-into values where select columns
-                                               from order-by update sset query-values]]
+                                               from order-by update sset query-values
+                                               modifiers]]
             [honeysql.core :as sql]
             [clojure.test :as test :refer [deftest is testing]]))
 
@@ -254,3 +255,11 @@
             {:except-all
              [{:select [:ip]}
               {:select [:ip] :from [:ip_location]}]})))))
+
+(deftest select-distinct-on
+  (testing "select distinct on"
+    (is (= ["SELECT DISTINCT ON(\"a\", \"b\") \"c\" FROM \"products\" "]
+           (-> (select :c)
+              (from :products)
+              (modifiers :distinct-on :a :b)
+              (sql/format :quoting :ansi))))))