Use is-empty and not-empty for string columns in quick filter drill (#42804)

src/metabase/lib/drill_thru/quick_filter.cljc

@@ -65,8 +65,11 @@
       []
 
       (= value :null)
-      [{:name "=" :filter (operator :is-null  field-ref)}
-       {:name "≠" :filter (operator :not-null field-ref)}]
+      (for [[op label] (if (or (lib.types.isa/string? column) (lib.types.isa/string-like? column))
+                         [[:is-empty "="] [:not-empty "≠"]]
+                         [[:is-null "="] [:not-null "≠"]])]
+        {:name   label
+         :filter (operator op field-ref)})
 
       (or (lib.types.isa/numeric? column)
           (lib.types.isa/temporal? column))

test/metabase/lib/drill_thru/quick_filter_test.cljc

@@ -139,6 +139,21 @@
                      :operators [{:name "="}
                                  {:name "≠"}]}})))
 
+(deftest ^:parallel returns-quick-filter-test-10
+  (testing "quick-filter should use is-empty and not-empty operators for string columns (#41783)"
+    (lib.drill-thru.tu/test-returns-drill
+      {:drill-type  :drill-thru/quick-filter
+       :click-type  :cell
+       :query-type  :unaggregated
+       :query-table "PRODUCTS"
+       :column-name "TITLE"
+       :custom-row  (assoc (get-in lib.drill-thru.tu/test-queries ["PRODUCTS" :unaggregated :row])
+                      "TITLE" nil)
+       :expected    {:type      :drill-thru/quick-filter
+                     :value     :null
+                     :operators [{:name "=", :filter [:is-empty {} [:field {} (meta/id :products :title)]]}
+                                 {:name "≠", :filter [:not-empty {} [:field {} (meta/id :products :title)]]}]}})))
+
 (deftest ^:parallel apply-quick-filter-on-correct-level-test
   (testing "quick-filter on an aggregation should introduce an new stage (#34346)"
     (lib.drill-thru.tu/test-drill-application