fix #377 by adopting @corasaurus-hex function as map=

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changes
 
 * 2.2.next in progress
+  * Address #377 by adding `honey.sql/map=` to convert a hash map into an equality condition (for a `WHERE` clause).
   * Address #281 by adding support for `SELECT * EXCEPT ..` and `SELECT * REPLACE ..` and `ARRAY<>` and `STRUCT<>` column types -- see [SQL Clause Reference - SELECT](https://cljdoc.org/d/com.github.seancorfield/honeysql/CURRENT/doc/getting-started/sql-clause-reference#select-select-distinct) and [SQL Clause Reference - DDL](https://cljdoc.org/d/com.github.seancorfield/honeysql/CURRENT/doc/getting-started/sql-clause-reference#ddl-clauses) respectively for more details.
   * Update `build-clj` to v0.6.7.
 

doc/clause-reference.md

@@ -674,6 +674,17 @@ The `:where` clause can have a single SQL expression, or
 a sequence of SQL expressions prefixed by either `:and`
 or `:or`. See examples of `:where` in various clauses above.
 
+Sometimes it is convenient to construct a `WHERE` clause that
+tests several columns for equality, and you might have a Clojure
+hash map containing those values. `honey.sql/map=` exists to
+convert a hash map of values into a condition that you can use
+in a `WHERE` clause to match against those columns and values:
+
+```clojure
+user=> (sql/format {:select :* :from :transaction :where (sql/map= {:type "sale" :productid 123})})
+["SELECT * FROM transaction WHERE (type = ?) AND (productid = ?)" "sale" 123]
+```
+
 ## group-by
 
 `:group-by` accepts a sequence of one or more SQL expressions.

src/honey/sql.cljc

@@ -1484,6 +1484,24 @@
     (when ignore-nil
       (swap! op-ignore-nil conj op))))
 
+;; helper functions to create HoneySQL data structures from other things
+
+(defn map=
+  "Given a hash map, return a condition structure that can be used in a
+  WHERE clause to test for equality:
+
+  {:select :* :from :table :where (sql/map= {:id 1})}
+
+  will produce: SELECT * FROM table WHERE id = ? (and a parameter of 1)"
+  [data]
+  (let [clauses (reduce-kv (fn [where col val]
+                             (conj where [:= col val]))
+                           []
+                           data)]
+    (if (= 1 (count clauses))
+      (first clauses)
+      (into [:and] clauses))))
+
 ;; aids to migration from HoneySQL 1.x -- these are deliberately undocumented
 ;; so as not to encourage their use for folks starting fresh with 2.x!
 

test/honey/sql_test.cljc

@@ -75,6 +75,8 @@
 (deftest general-tests
   (is (= ["SELECT * FROM \"table\" WHERE \"id\" = ?" 1]
          (sut/format {:select [:*] :from [:table] :where [:= :id 1]} {:quoted true})))
+  (is (= ["SELECT * FROM \"table\" WHERE \"id\" = ?" 1]
+         (sut/format {:select [:*] :from [:table] :where (sut/map= {:id 1})} {:quoted true})))
   (is (= ["SELECT \"t\".* FROM \"table\" AS \"t\" WHERE \"id\" = ?" 1]
          (sut/format {:select [:t.*] :from [[:table :t]] :where [:= :id 1]} {:quoted true})))
   (is (= ["SELECT * FROM \"table\" GROUP BY \"foo\", \"bar\""]