use converters API rather than from_db_value()

Author: timgraham

django_mongodb/fields/json.py

@@ -1,7 +1,4 @@
-import json
-
 from django.db import NotSupportedError
-from django.db.models import JSONField
 from django.db.models.fields.json import (
     ContainedBy,
     DataContains,
@@ -28,20 +25,6 @@ def data_contains(self, compiler, connection):  # noqa: ARG001
     raise NotSupportedError("contains lookup is not supported on this database backend.")
 
 
-_from_db_value = JSONField.from_db_value
-
-
-def from_db_value(self, value, expression, connection):
-    """
-    Transforms the value retrieved from the database into a string if the database
-    vendor is MongoDB. This is necessary because MongoDB saves the data as a
-    dictionary, and converting it to a JSON string allows for proper decoding.
-    """
-    if connection.vendor == "mongodb":
-        value = json.dumps(value)
-    return _from_db_value(self, value, expression, connection)
-
-
 def has_key_lookup(self, compiler, connection):
     rhs = self.rhs
     lhs = process_lhs(self, compiler, connection)
@@ -155,7 +138,6 @@ def register_json_field():
     HasKeyLookup.as_mql = has_key_lookup
     HasKeys.mongo_operator = "$and"
     JSONExact.process_rhs = json_process_rhs
-    JSONField.from_db_value = from_db_value
     KeyTransform.as_mql = key_transform
     KeyTransformIn.as_mql = key_transform_in
     KeyTransformIsNull.as_mql = key_transform_isnull

django_mongodb/operations.py

@@ -75,6 +75,8 @@ def get_db_converters(self, expression):
                 converters.append(self.convert_datetimefield_value)
         elif internal_type == "DecimalField":
             converters.append(self.convert_decimalfield_value)
+        elif internal_type == "JSONField":
+            converters.append(self.convert_jsonfield_value)
         elif internal_type == "TimeField":
             converters.append(self.convert_timefield_value)
         elif internal_type == "UUIDField":
@@ -97,6 +99,13 @@ def convert_decimalfield_value(self, value, expression, connection):
             value = value.to_decimal()
         return value
 
+    def convert_jsonfield_value(self, value, expression, connection):
+        """
+        Convert dict data to a string so that JSONField.from_db_value() can
+        decode it using json.loads().
+        """
+        return json.dumps(value)
+
     def convert_timefield_value(self, value, expression, connection):
         if value is not None:
             value = value.time()