add support for ExpressionWrapper

Author: timgraham

django_mongodb/expressions.py

@@ -1,14 +1,19 @@
-from django.db.models.expressions import Col, Value
+from django.db.models.expressions import Col, ExpressionWrapper, Value
 
 
 def col(self, compiler, connection):  # noqa: ARG001
     return f"${self.target.column}"
 
 
+def expression_wrapper(self, compiler, connection):
+    return self.expression.as_mql(compiler, connection)
+
+
 def value(self, compiler, connection):  # noqa: ARG001
     return {"$literal": self.value}
 
 
 def register_expressions():
     Col.as_mql = col
+    ExpressionWrapper.as_mql = expression_wrapper
     Value.as_mql = value

django_mongodb/features.py

@@ -175,21 +175,18 @@ class DatabaseFeatures(BaseDatabaseFeatures):
             "db_functions.datetime.test_extract_trunc.DateFunctionTests.test_extract_outerref",
             "db_functions.datetime.test_extract_trunc.DateFunctionTests.test_trunc_subquery_with_parameters",
             "lookup.tests.LookupQueryingTests.test_filter_subquery_lhs",
-            # ExpressionWrapper not supported.
-            "annotations.tests.NonAggregateAnnotationTestCase.test_combined_expression_annotation_with_aggregation",
-            "annotations.tests.NonAggregateAnnotationTestCase.test_combined_f_expression_annotation_with_aggregation",
-            "annotations.tests.NonAggregateAnnotationTestCase.test_empty_expression_annotation",
-            "annotations.tests.NonAggregateAnnotationTestCase.test_full_expression_annotation",
+            # Invalid $project :: caused by :: Unknown expression $count,
             "annotations.tests.NonAggregateAnnotationTestCase.test_full_expression_annotation_with_aggregation",
             "annotations.tests.NonAggregateAnnotationTestCase.test_grouping_by_q_expression_annotation",
-            "annotations.tests.NonAggregateAnnotationTestCase.test_mixed_type_annotation_numbers",
             "annotations.tests.NonAggregateAnnotationTestCase.test_q_expression_annotation_with_aggregation",
-            "lookup.tests.LookupQueryingTests.test_filter_wrapped_lookup_lhs",
             # CombinedExpression not implemented.
             "annotations.tests.NonAggregateAnnotationTestCase.test_combined_annotation_commutative",
+            "annotations.tests.NonAggregateAnnotationTestCase.test_combined_expression_annotation_with_aggregation",
+            "annotations.tests.NonAggregateAnnotationTestCase.test_combined_f_expression_annotation_with_aggregation",
             "annotations.tests.NonAggregateAnnotationTestCase.test_decimal_annotation",
             "annotations.tests.NonAggregateAnnotationTestCase.test_defer_annotation",
             "annotations.tests.NonAggregateAnnotationTestCase.test_filter_decimal_annotation",
+            "annotations.tests.NonAggregateAnnotationTestCase.test_mixed_type_annotation_numbers",
             "annotations.tests.NonAggregateAnnotationTestCase.test_values_annotation",
             # Func not implemented.
             "annotations.tests.NonAggregateAnnotationTestCase.test_custom_functions",

django_mongodb/query.py

@@ -2,6 +2,7 @@
 
 from django.core.exceptions import EmptyResultSet, FullResultSet
 from django.db import DatabaseError, IntegrityError
+from django.db.models import Value
 from django.db.models.sql.where import AND, XOR, WhereNode
 from pymongo import ASCENDING, DESCENDING
 from pymongo.errors import DuplicateKeyError, PyMongoError
@@ -91,7 +92,12 @@ def get_cursor(self):
                 column = expr.target.column
             except AttributeError:
                 # Generate the MQL for an annotation.
-                fields[name] = expr.as_mql(self.compiler, self.connection)
+                try:
+                    fields[name] = expr.as_mql(self.compiler, self.connection)
+                except EmptyResultSet:
+                    fields[name] = Value(False).as_mql(self.compiler, self.connection)
+                except FullResultSet:
+                    fields[name] = Value(True).as_mql(self.compiler, self.connection)
             else:
                 # If name != column, then this is an annotatation referencing
                 # another column.