diff options
| -rw-r--r-- | README.md | 23 | ||||
| -rw-r--r-- | src/clojure_sql/dsl.clj | 30 |
2 files changed, 48 insertions, 5 deletions
@@ -210,6 +210,29 @@ be the return value of the associated query function call (`deref`, ### 0.2.0 +* **Breaking:** `group` has changed significantly. It now takes a third + argument which is an 'auxiliary projection'. The fields in the + resulting query will be the union of the grouped fields and the + projection (with the projection taking precedence). Each value in + the projection must be, in some way, an aggregate of the grouped + values (this is not, and cannot really be, enforced, but we try to + warn you if you're obviously wrong). + + :::clojure + (-> (q/table :users) + (q/project [:age :name]) + (q/group [:age] {'(string_agg :name ",") :names})) + ;=> ["SELECT \"users1785\".\"age\" AS \"age\", (\"string_agg\"(\"users1785\".\"name\",?)) AS \"names\" + FROM \"users\" AS \"users1785\" + GROUP BY \"users1785\".\"age\"" + ","] + + (-> (q/table :users) + (q/project [:age :name]) + (q/group [:age] {:name :name})) + ;=> Exception! Expr is not a function application - could not + possible be an aggregate + * **Breaking:** Remove `having`, use `select` instead now * `sort` can now sort on expressions, not just table names diff --git a/src/clojure_sql/dsl.clj b/src/clojure_sql/dsl.clj index 16bc2e5..413b9c0 100644 --- a/src/clojure_sql/dsl.clj +++ b/src/clojure_sql/dsl.clj @@ -61,6 +61,10 @@ :right right :type type }))) +(defn ^:private not-a-function-expression [expr] + (throw (ex-info "Expr is not a function application - could not possibly be an aggregate" + {:expr expr}))) + (defn ^:private invalid-union [queries] (throw (ex-info "Cannot union queries with different fields" {:queries queries}))) @@ -326,19 +330,35 @@ (defn group "Apply a grouping to a query. - `fields` is a sequential collection of fields to group by. + `fields` is a collection of fields to group by. `projection` is a + map with which to perform a projection. + + The projection must perform an aggregate function on each + non-grouped field, or else the resulting group is invalid. This is + not verifiable without knowing the full set of aggregate + functions (which is not possible in general), so any projection will + be accepted as long as a function is called as a part of each + projection. If the query has already been grouped then this will create a subquery." - [query fields] + [query fields projection] (let [query (if (:group query) (convert-to-subquery query) query) fields-seq (if (sequential? fields) fields - [fields])] - (assoc query :group (map (partial resolve-field (:tables query) (:fields query)) - fields-seq)))) + [fields]) + fields-map (into {} (map vector fields fields))] + (doseq [[expr name] projection] + (try (or (some #{expr} fields-seq) + (seq expr)) + (catch Exception e + (not-a-function-expression expr)))) + (-> query + (assoc :group (map (partial resolve-field (:tables query) (:fields query)) + fields-seq)) + (project (into fields-map projection))))) (defn take "Limit the number of results of a query. |