QuerySelectField: Add support for blank choice when using groups

Author: Lukas0907

pyproject.toml

@@ -18,7 +18,7 @@ classifiers = [
 ]
 requires-python = ">=3.9"
 dependencies = [
-    "WTForms>=3.1",
+    "WTForms>=3.1.2",
     "SQLAlchemy>=1.4",
 ]
 dynamic = ["version"]

src/wtforms_sqlalchemy/fields.py

@@ -147,9 +147,12 @@ def _get_object_list(self):
             self._object_list = list((str(get_pk(obj)), obj) for obj in query)
         return self._object_list
 
+    def _get_blank_choice(self):
+        return (self.blank_value, self.blank_text, self.data is None, {})
+
     def iter_choices(self):
         if self.allow_blank:
-            yield (self.blank_value, self.blank_text, self.data is None, {})
+            yield self._get_blank_choice()
 
         for pk, obj in self._get_object_list():
             yield (pk, self.get_label(obj), obj == self.data, self.get_render_kw(obj))
@@ -159,6 +162,9 @@ def has_groups(self):
 
     def iter_groups(self):
         if self.has_groups():
+            if self.allow_blank:
+                yield (None, [self._get_blank_choice()])
+
             groups = defaultdict(list)
             for pk, obj in self._get_object_list():
                 groups[self.get_group(obj)].append((pk, obj))

tests/test_main.py

@@ -217,6 +217,7 @@ class F(Form):
         self.assertEqual(
             form.d(),
             [
+                (None, [("", "", True, {})]),
                 (
                     "a",
                     [("hello1", "apple", False, {}), ("hello3", "apricot", False, {})],
@@ -260,6 +261,7 @@ class F(Form):
         self.assertEqual(
             form.d(),
             [
+                (None, [("", "", False, {})]),
                 (
                     "a",
                     [("hello1", "apple", False, {}), ("hello3", "apricot", True, {})],