fix: dont repeatedly evaluate queryset in model ACs

autocomplete/shortcuts.py

@@ -75,6 +75,12 @@ def __init__(self, queryset, label_for_record):
         self.queryset = queryset
         self.label_for_record = label_for_record
 
+    def __iter__(self, *args, **kwargs):
+        return (self.map_record(r) for r in self.queryset)
+
+    def map_record(self, record):
+        return {"key": record.id, "label": self.label_for_record(record)}
+
     def __getitem__(self, key):
         # Handle both single index and slice objects
         if isinstance(key, int):
@@ -84,10 +90,7 @@ def __getitem__(self, key):
         else:
             raise TypeError("Invalid argument type")
 
-        mapped = [
-            {"key": record.id, "label": self.label_for_record(record)}
-            for record in records
-        ]
+        mapped = [self.map_record(r) for r in records]
 
         if isinstance(key, int):
             return mapped[0]

tests/test_model_ac.py

@@ -36,7 +36,7 @@ def test_model_ac_search():
     ]
 
 
-def test_model_ac_search_max_results():
+def test_model_ac_search_max_results(django_assert_max_num_queries):
     class PersonModelAC(ModelAutocomplete):
         model = Person
         search_attrs = ["name"]
@@ -47,6 +47,22 @@ class PersonModelAC(ModelAutocomplete):
     p3 = PersonFactory(name="John3")
     p4 = PersonFactory(name="Jones")
 
-    results = PersonModelAC.search_items("Joh", ContextArg(None, None))
+    with django_assert_max_num_queries(1):
+        results = PersonModelAC.search_items("Joh", ContextArg(None, None))
     # should still contain 3 results, the view is responsible for truncating
     assert len(results) == 3
+
+
+def test_num_queries(django_assert_max_num_queries):
+    """
+    regression: the queryset iterable wrapper was repeatedly evaluating the queryset
+    """
+
+    p1 = PersonFactory(name="John1")
+    p2 = PersonFactory(name="John2")
+    p3 = PersonFactory(name="John3")
+    p4 = PersonFactory(name="Jones")
+
+    with django_assert_max_num_queries(1):
+        results = PersonModelAC.search_items("Joh", ContextArg(None, None))
+        mapped_results = PersonModelAC.map_search_results(results, [])