From 25097af134e9c441076a295b98054c154f53af7e Mon Sep 17 00:00:00 2001
From: Sean Corfield <sean@corfield.org>
Date: Sat, 26 Sep 2020 15:16:12 -0700
Subject: [PATCH] First cut of on conflict support

---
 src/honey/sql.cljc       | 18 ++++++++++++++++++
 test/honey/sql_test.cljc |  4 ++++
 2 files changed, 22 insertions(+)

diff --git a/src/honey/sql.cljc b/src/honey/sql.cljc
index 17f21b9..4a0ed91 100644
--- a/src/honey/sql.cljc
+++ b/src/honey/sql.cljc
@@ -21,6 +21,7 @@
    :join :left-join :right-join :inner-join :outer-join :full-join
    :cross-join
    :where :group-by :having :order-by :limit :offset :values
+   :on-conflict :on-constraint :do-nothing :do-update-set
    :returning])
 
 (defn- add-clause-before
@@ -297,6 +298,19 @@
                    xs)]
     (into [(str (sql-kw k) " " (str/join ", " sqls))] params)))
 
+(defn- format-on-conflict [k x]
+  (if (keyword? x)
+    [(str (sql-kw k) " (" (format-entity x) ")")]
+    (let [[sql & params] (format-dsl x)]
+      (into [(str (sql-kw k) " " sql)] params))))
+
+(defn- format-do-update-set [k x]
+  (if (keyword? x)
+    (let [e (format-entity x {:drop-ns? true})]
+      [(str (sql-kw k) " " e " = EXCLUDED." e)])
+    (let [[sql & params] (format-set-exprs :set x)]
+      (into [(str (sql-kw k) " " sql)] params))))
+
 (def ^:private base-clause-order
   "The (base) order for known clauses. Can have items added and removed.
 
@@ -341,6 +355,10 @@
          :limit          #'format-on-expr
          :offset         #'format-on-expr
          :values         #'format-values
+         :on-conflict    #'format-on-conflict
+         :on-constraint  #'format-selector
+         :do-nothing     (fn [k _] (vector (sql-kw k)))
+         :do-update-set  #'format-do-update-set
          :returning      #'format-selects}))
 
 (assert (= (set @base-clause-order)
diff --git a/test/honey/sql_test.cljc b/test/honey/sql_test.cljc
index e39f323..1401019 100644
--- a/test/honey/sql_test.cljc
+++ b/test/honey/sql_test.cljc
@@ -398,3 +398,7 @@
          (format {:select [:*]
                   :from [[:foo :f]]
                   :cross-join [[:bar :b]]}))))
+
+(comment ; make on conflict tests, based on nilenso repo and PG docs
+  (format {:insert-into :foo, :values [[1 2 3]], :on-conflict :e :do-nothing true})
+  (format {:insert-into :foo, :values [[1 2 3]], :on-conflict {:on-constraint :foo_key} :do-update-set {:a 42 :b :excluded.b}}))