fixes #530 by supporting :using-gin in :create-index

Signed-off-by: Sean Corfield <sean@corfield.org>

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 * 2.6.next in progress
   * Address [#531](https://github.com/seancorfield/honeysql/issues/531) and [#527](https://github.com/seancorfield/honeysql/issues/527) by adding tests and more documentation for `:composite`; fix bug in `set-dialect!` where clause order is not restored.
+  * Address [#530](https://github.com/seancorfield/honeysql/issues/530) by adding support for `:using-gin` to `:create-index`.
   * Address [#529](https://github.com/seancorfield/honeysql/issues/529) by fixing `:join` special syntax to support aliases and to handle expressions the same way `select` / `from` etc handle them (extra `[...]` nesting).
   * Add example of mixed `DO UPDATE SET` with `EXCLUDED` and regular SQL expressions.
   * Improve exception message when un-`lift`-ed JSON expressions are used in the DSL.

doc/clause-reference.md

@@ -141,6 +141,14 @@ user=> (sql/format (h/create-index [:unique :another-idx :if-not-exists] [:fruit
 ["CREATE UNIQUE INDEX IF NOT EXISTS another_idx ON fruit (color, LOWER(appearance))"]
 ```
 
+`USING GIN` index creation is also possible using the keyword `:using-gin` after
+the table name (or the symbol `using-gin`):
+
+```clojure
+user=> (sql/format {:create-index [:my-idx [:fruit :using-gin :appearance]]})
+["CREATE INDEX my_idx ON fruit USING GIN (appearance)"]
+```
+
 ### rename-table
 
 Used with `:alter-table`,

src/honey/sql.cljc

@@ -1267,10 +1267,14 @@
 (defn- format-create-index [k clauses]
   (let [[index-spec [table & exprs]] clauses
         [pre entity ine & more] (destructure-ddl-item index-spec (str (sql-kw k) " options"))
+        [using & exprs] (if (= :using-gin (first exprs))
+                          exprs
+                          (cons nil exprs))
         [sqls params] (format-expr-list exprs)]
     (into [(str/join " " (remove empty?
                                  (-> ["CREATE" pre "INDEX" ine entity
                                       "ON" (format-entity table)
+                                      (when using (sql-kw using))
                                       (str "(" (str/join ", " sqls) ")")]
                                      (into more))))]
           params)))

test/honey/sql/helpers_test.cljc

@@ -980,7 +980,12 @@
     (is (= ["CREATE UNIQUE INDEX IF NOT EXISTS my_column_idx ON my_table (my_column)"]
            (sql/format (create-index [:unique :my-column-idx :if-not-exists] [:my-table :my-column]))))
     (is (= ["CREATE INDEX my_column_idx ON my_table (LOWER(my_column))"]
-           (sql/format (create-index :my-column-idx [:my-table :%lower.my-column]))))))
+           (sql/format (create-index :my-column-idx [:my-table :%lower.my-column])))))
+  (testing "PostgreSQL extensions (USING GIN)"
+    (is (= ["CREATE INDEX my_column_idx ON my_table USING GIN (my_column)"]
+           (sql/format {:create-index [:my-column-idx [:my-table :using-gin :my-column]]})))
+    (is (= ["CREATE INDEX my_column_idx ON my_table USING GIN (my_column)"]
+           (sql/format (create-index :my-column-idx [:my-table :using-gin :my-column]))))))
 
 (deftest join-with-alias
   (is (= ["SELECT * FROM foo LEFT JOIN (populatons AS pm INNER JOIN customers AS pc ON (pm.id = pc.id) AND (pm.other_id = pc.other_id)) ON foo.fk_id = pm.id"]