Support locking selects

This will need documentation before being merged.

src/honeysql/format.clj

@@ -188,6 +188,7 @@
    :order-by 190
    :limit 200
    :offset 210
+   :lock 215
    :values 220
    :query-values 230})
 
@@ -426,6 +427,22 @@
 (defmethod format-clause :offset [[_ offset] _]
   (str "OFFSET " (to-sql offset)))
 
+(defmulti format-lock-clause identity)
+
+(defmethod format-lock-clause :update [_]
+  "FOR UPDATE")
+
+(defmethod format-lock-clause :mysql-share [_]
+  "LOCK IN SHARE MODE")
+
+(defmethod format-lock-clause :postgresql-share [_]
+  "FOR SHARE")
+
+(defmethod format-clause :lock [[_ lock] _]
+  (let [{:keys [mode wait]} lock
+        clause (format-lock-clause mode)]
+    (str clause (when (false? wait) " NOWAIT"))))
+
 (defmethod format-clause :insert-into [[_ table] _]
   (if (and (sequential? table) (sequential? (first table)))
     (str "INSERT INTO "

src/honeysql/helpers.clj

@@ -154,6 +154,11 @@
     m
     (assoc m :offset (if (coll? o) (first o) o))))
 
+(defhelper lock [m lock]
+  (cond-> m
+          lock
+          (assoc :lock lock)))
+
 (defhelper modifiers [m ms]
   (if (nil? ms)
     m

test/honeysql/core_test.clj

@@ -60,7 +60,12 @@
     (testing "SQL data formats correctly with alternate param naming"
       (is (= (sql/format m1 :params {:param1 "gabba" :param2 2} :parameterizer :postgresql)
              ["SELECT DISTINCT f.*, b.baz, c.quux, b.bla AS bla_bla, now(), @x := 10 FROM foo f, baz b INNER JOIN draq ON f.b = draq.x LEFT JOIN clod c ON f.a = c.d RIGHT JOIN bock ON bock.z = c.e FULL JOIN beck ON beck.x = c.y WHERE ((f.a = $1 AND b.baz <> $2) OR (1 < 2 AND 2 < 3) OR (f.e in (1, $3, 3)) OR f.e BETWEEN 10 AND 20) GROUP BY f.a HAVING 0 < f.e ORDER BY b.baz DESC, c.quux LIMIT 50 OFFSET 10 "
-              "bort" "gabba" 2])))))
+              "bort" "gabba" 2])))
+    (testing "Locking"
+      (is (= ["SELECT DISTINCT f.*, b.baz, c.quux, b.bla AS bla_bla, now(), @x := 10 FROM foo f, baz b INNER JOIN draq ON f.b = draq.x LEFT JOIN clod c ON f.a = c.d RIGHT JOIN bock ON bock.z = c.e FULL JOIN beck ON beck.x = c.y WHERE ((f.a = ? AND b.baz <> ?) OR (1 < 2 AND 2 < 3) OR (f.e in (1, ?, 3)) OR f.e BETWEEN 10 AND 20) GROUP BY f.a HAVING 0 < f.e ORDER BY b.baz DESC, c.quux LIMIT 50 OFFSET 10 FOR UPDATE "
+              "bort" "gabba" 2]
+             (sql/format (assoc m1 :lock {:mode :update})
+                         {:param1 "gabba" :param2 2}))))))
 
 (deftest test-cast
   (is (= ["SELECT foo, CAST(bar AS integer)"]