[QueryBuilder] Implement get_creation_statistics for SQLite backend (#6763)

This commit improves backend parity between two database backends by implementing `get_creation_statistics` for the SQLite backend. It achieves this by using an alternative method to implement `date_trunc`, which is available in PostgreSQL but not in SQLite.

Author: rabbull

src/aiida/storage/psql_dos/orm/querybuilder/main.py

@@ -798,8 +798,27 @@ def get_creation_statistics(self, user_pk: Optional[int] = None) -> Dict[str, An
 
         total_query = session.query(self.Node)
         types_query = session.query(self.Node.node_type.label('typestring'), sa_func.count(self.Node.id))
+
+        dialect = session.bind.dialect.name
+        date_format = '%Y-%m-%d'
+
+        if dialect == 'sqlite':
+            cday = sa_func.strftime(date_format, sa_func.datetime(self.Node.ctime, 'localtime'))
+
+            def date_to_str(d):
+                return d
+
+        elif dialect == 'postgresql':
+            cday = sa_func.date_trunc('day', self.Node.ctime)
+
+            def date_to_str(d):
+                return d.strftime(date_format)
+
+        else:
+            raise NotImplementedError(f'unsupported dialect: {dialect}')
+
         stat_query = session.query(
-            sa_func.date_trunc('day', self.Node.ctime).label('cday'),
+            cday.label('cday'),
             sa_func.count(self.Node.id),
         )
 
@@ -817,7 +836,7 @@ def get_creation_statistics(self, user_pk: Optional[int] = None) -> Dict[str, An
         # Nodes created per day
         stat = stat_query.group_by('cday').order_by('cday').all()
 
-        ctime_by_day = {_[0].strftime('%Y-%m-%d'): _[1] for _ in stat}
+        ctime_by_day = {date_to_str(entry[0]): entry[1] for entry in stat}
         retdict['ctime_by_day'] = ctime_by_day
 
         return retdict

tests/orm/test_querybuilder.py

@@ -1581,9 +1581,6 @@ class TestManager:
     def init_db(self, backend):
         self.backend = backend
 
-    # This fails with sqlite with:
-    # sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such function: date_trunc
-    @pytest.mark.requires_psql
     def test_statistics(self):
         """Test if the statistics query works properly.
 
@@ -1620,9 +1617,6 @@ def store_and_add(n, statistics):
 
         assert new_db_statistics == expected_db_statistics
 
-    # This fails with sqlite with:
-    # sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such function: date_trunc
-    @pytest.mark.requires_psql
     def test_statistics_default_class(self):
         """Test if the statistics query works properly.
 

tests/restapi/test_statistics.py

@@ -33,10 +33,7 @@ def linearize_namespace(tree_namespace, linear_namespace=None):
     return linear_namespace
 
 
-# This test does not work with SQLite since it uses the `statistics` endpoint,
-# which uses `date_trunc` under the hood, which is not implemented in SQLite.
 @pytest.mark.usefixtures('populate_restapi_database')
-@pytest.mark.requires_psql
 def test_count_consistency(restapi_server, server_url):
     """Test the consistency in values between full_type_count and statistics"""
     server = restapi_server()