Handle array as path and update unit test.

Author: WaVEV

django_mongodb_backend/fields/array.py

@@ -4,10 +4,11 @@
 from django.db.models import Field, Func, IntegerField, Transform, Value
 from django.db.models.fields.mixins import CheckFieldDefaultMixin
 from django.db.models.lookups import Exact, FieldGetDbPrepValueMixin, In, Lookup
+from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 
 from ..forms import SimpleArrayField
-from ..query_utils import process_lhs, process_rhs
+from ..query_utils import is_constant_value, process_lhs, process_rhs
 from ..utils import prefix_validation_error
 from ..validators import ArrayMaxLengthValidator, LengthValidator
 
@@ -236,6 +237,20 @@ def as_mql_expr(self, compiler, connection):
             for expr in self.get_source_expressions()
         ]
 
+    def as_mql_path(self, compiler, connection):
+        return [
+            expr.as_mql(compiler, connection, as_path=True)
+            for expr in self.get_source_expressions()
+        ]
+
+    @cached_property
+    def can_use_path(self):
+        return all(is_constant_value(expr) for expr in self.get_source_expressions())
+
+    @property
+    def is_simple_column(self):
+        return False
+
 
 class ArrayRHSMixin:
     def __init__(self, lhs, rhs):

django_mongodb_backend/fields/embedded_model.py

@@ -8,6 +8,7 @@
 from django.utils.functional import cached_property
 
 from .. import forms
+from ..query_utils import valid_path_key_name
 
 
 class EmbeddedModelField(models.Field):
@@ -174,8 +175,8 @@ def can_use_path(self):
     @cached_property
     def is_simple_column(self):
         previous = self
-        while isinstance(previous, KeyTransform):
-            if not previous.key_name.isalnum():
+        while isinstance(previous, EmbeddedModelTransform):
+            if not valid_path_key_name(previous._field.column):
                 return False
             previous = previous.lhs
         return previous.is_simple_column

django_mongodb_backend/fields/embedded_model_array.py

@@ -9,7 +9,7 @@
 
 from .. import forms
 from ..lookups import builtin_lookup_path
-from ..query_utils import process_lhs, process_rhs
+from ..query_utils import process_lhs, process_rhs, valid_path_key_name
 from . import EmbeddedModelField
 from .array import ArrayField, ArrayLenTransform
 
@@ -240,6 +240,7 @@ def __init__(self, field, *args, **kwargs):
         column_name = f"$item.{field.column}"
         column_target.db_column = column_name
         column_target.set_attributes_from_name(column_name)
+        self._field = field
         self._lhs = Col(None, column_target)
         self._sub_transform = None
 
@@ -255,7 +256,7 @@ def can_use_path(self):
     def is_simple_column(self):
         previous = self
         while isinstance(previous, EmbeddedModelArrayFieldTransform):
-            if not previous.key_name.isalnum():
+            if not valid_path_key_name(previous._field.column):
                 return False
             previous = previous.lhs
         return previous.is_simple_column and self._lhs.is_simple_column

django_mongodb_backend/fields/json.py

@@ -18,7 +18,7 @@
 )
 
 from ..lookups import builtin_lookup_expr, builtin_lookup_path
-from ..query_utils import process_lhs, process_rhs
+from ..query_utils import process_lhs, process_rhs, valid_path_key_name
 
 
 def build_json_mql_path(lhs, key_transforms, as_path=False):
@@ -75,7 +75,7 @@ def _has_key_predicate(path, root_column=None, negated=False, as_path=False):
 @property
 def has_key_check_simple_expression(self):
     rhs = [self.rhs] if not isinstance(self.rhs, (list, tuple)) else self.rhs
-    return self.is_simple_column and all(key.isalnum() for key in rhs)
+    return self.is_simple_column and all(valid_path_key_name(key) for key in rhs)
 
 
 def has_key_lookup(self, compiler, connection, as_path=False):
@@ -231,7 +231,7 @@ def key_transform_numeric_lookup_mixin_path(self, compiler, connection):
 def keytransform_is_simple_column(self):
     previous = self
     while isinstance(previous, KeyTransform):
-        if not previous.key_name.isalnum():
+        if not valid_path_key_name(previous.key_name):
             return False
         previous = previous.lhs
     return previous.is_simple_column

django_mongodb_backend/query_utils.py

@@ -1,6 +1,8 @@
+import re
+
 from django.core.exceptions import FullResultSet
 from django.db.models.aggregates import Aggregate
-from django.db.models.expressions import CombinedExpression, Value
+from django.db.models.expressions import CombinedExpression, Func, Value
 from django.db.models.sql.query import Query
 
 
@@ -74,17 +76,24 @@ def is_constant_value(value):
     if hasattr(value, "get_source_expressions"):
         # Temporary: similar limitation as above, sub-expressions should be
         # resolved in the future
-        simple_sub_expressions = all(map(is_constant_value, value.get_source_expressions()))
+        constants_sub_expressions = all(map(is_constant_value, value.get_source_expressions()))
     else:
-        simple_sub_expressions = True
-    return (
-        simple_sub_expressions
-        and isinstance(value, Value)
-        and not (
-            isinstance(value, Query)
-            or value.contains_aggregate
-            or value.contains_over_clause
-            or value.contains_column_references
-            or value.contains_subquery
-        )
+        constants_sub_expressions = True
+    constants_sub_expressions = constants_sub_expressions and not (
+        isinstance(value, Query)
+        or value.contains_aggregate
+        or value.contains_over_clause
+        or value.contains_column_references
+        or value.contains_subquery
+    )
+    return constants_sub_expressions and (
+        isinstance(value, Value)
+        or
+        # Some closed functions cannot yet be converted to constant values.
+        # Allow Func with can_use_path as a temporary exception.
+        (isinstance(value, Func) and value.can_use_path)
     )
+
+
+def valid_path_key_name(key_name):
+    return bool(re.fullmatch(r"[A-Za-z0-9_]+", key_name))