address #474

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changes
 
 * 2.4.next in progress
+  * Address [#474](https://github.com/seancorfield/honeysql/issues/474) by adding dot-selection special syntax. Documentation TBD!
   * Improve docstrings for PostgreSQL operators via PR [#473](https://github.com/seancorfield/honeysql/pull/473) [@holyjak](https://github.com/holyjak).
   * Address [#471](https://github.com/seancorfield/honeysql/issues/471) by supported interspersed SQL keywords in function calls. Documentation TBD!
   * Fix [#467](https://github.com/seancorfield/honeysql/issues/467) by allowing single keywords (symbols) as a short hand for a single-element sequence in more constructs via PR [#470](https://github.com/seancorfield/honeysql/pull/470) [@p-himik](https://github.com/p-himik).

src/honey/sql.cljc

@@ -1472,6 +1472,9 @@
     :primary-key #'function-0
     :references  #'function-1
     :unique      #'function-1-opt
+    :.           (fn [_ [expr col]]
+                   (let [[sql & params] (format-expr expr)]
+                     (into [(str sql "." (format-entity col))] params)))
     ;; used in DDL to force rendering as a SQL entity instead
     ;; of a SQL keyword:
     :entity      (fn [_ [e]] [(format-entity e)])

test/honey/sql_test.cljc

@@ -1130,3 +1130,14 @@ ORDER BY id = ? DESC
     (is (= ["SELECT XMLELEMENT(NAME \"foo$bar\", XMLATTRIBUTES('xyz' AS \"a&b\"))"]
            (sut/format {:select [[[:xmlelement :*name :foo$bar
                                    [:xmlattributes [:inline "xyz"] :*as :a&b]]]]})))))
+
+(deftest issue-474-dot-selection
+  (testing "basic dot selection"
+    (is (= ["SELECT a.b, c.d, e.f"]
+           (let [t :a c :d]
+             (sut/format {:select [[[:. t :b]] [[:. :c c]] [[:. :e :f]]]})))))
+  (testing "basic field selection from composite"
+    (is (= ["SELECT (v).*, (w).x, (Y(z)).*"]
+           (sut/format '{select (((. (nest v) *))
+                                 ((. (nest w) x))
+                                 ((. (nest (y z)) *)))})))))