Fix issue with deriving embedded field types

Fields inside `ValueObject` fields were always considered Strings
when deriving Postgres mapping. This commit considers the
field object embedded within `_ShadowField` to derive the
appropriate field type when generating model mappings.

src/protean/adapters/repository/sqlalchemy.py

@@ -31,6 +31,7 @@
     Text,
 )
 from protean.fields.association import Reference, _ReferenceField
+from protean.fields.embedded import _ShadowField
 from protean.globals import current_domain, current_uow
 from protean.port.dao import BaseDAO, BaseLookup, ResultSet
 from protean.port.provider import BaseProvider
@@ -51,6 +52,7 @@ class GUID(TypeDecorator):
     """
 
     impl = CHAR
+    cache_ok = True
 
     def load_dialect_impl(self, dialect):
         if dialect.name == "postgresql":
@@ -104,7 +106,7 @@ def _get_identity_type():
 class DeclarativeMeta(sa_dec.DeclarativeMeta, ABCMeta):
     """ Metaclass for the Sqlalchemy declarative schema """
 
-    def __init__(cls, classname, bases, dict_):
+    def __init__(cls, classname, bases, dict_):  # noqa: C901
         # Update the class attrs with the entity attributes
 
         field_mapping = {
@@ -129,6 +131,10 @@ def __init__(cls, classname, bases, dict_):
 
                 # Map the field if not in attributes
                 if attribute_name not in cls.__dict__:
+                    # Derive field based on field enclosed within ShadowField
+                    if isinstance(field_obj, _ShadowField):
+                        field_obj = field_obj.field_obj
+
                     field_cls = type(field_obj)
                     type_args = []
                     type_kwargs = {}

tests/adapters/repository/sqlalchemy_repo/postgresql/conftest.py

@@ -31,7 +31,7 @@ def setup_db():
     with domain.domain_context():
         # Create all associated tables
         from .elements import Alien, ComplexUser, Person, User
-        from .test_associations import Comment, Post
+        from .test_associations import Comment, Post, Audit
         from .test_persistence import Event
 
         domain.register(Alien)
@@ -41,6 +41,7 @@ def setup_db():
         domain.register(User)
         domain.register(Post)
         domain.register(Comment)
+        domain.register(Audit)
 
         domain.get_dao(Alien)
         domain.get_dao(ComplexUser)
@@ -49,6 +50,7 @@ def setup_db():
         domain.get_dao(User)
         domain.get_dao(Post)
         domain.get_dao(Comment)
+        domain.get_dao(Audit)
 
         for provider in domain.providers_list():
             provider._metadata.create_all()

tests/adapters/repository/sqlalchemy_repo/postgresql/test_associations.py

@@ -2,8 +2,8 @@
 
 import pytest
 
-from protean import BaseAggregate, BaseEntity, UnitOfWork
-from protean.fields import DateTime, HasMany, Reference, Text
+from protean import BaseAggregate, BaseEntity, BaseValueObject, UnitOfWork
+from protean.fields import DateTime, Dict, HasMany, Reference, Text, ValueObject
 
 
 class Comment(BaseEntity):
@@ -16,11 +16,19 @@ class Meta:
         aggregate_cls = "Post"
 
 
+class Permission(BaseValueObject):
+    dict_object = Dict()
+
+
 class Post(BaseAggregate):
     content = Text(required=True)
     comments = HasMany(Comment)
 
 
+class Audit(BaseAggregate):
+    permission = ValueObject(Permission)
+
+
 @pytest.mark.postgresql
 def test_updating_a_has_many_association(test_domain):
     test_domain.register(Post)
@@ -41,3 +49,16 @@ def test_updating_a_has_many_association(test_domain):
         refreshed_comment.content = "baz"
         refreshed_post.add_comments(refreshed_comment)
         post_repo.add(refreshed_post)
+
+
+@pytest.mark.postgresql
+def test_embedded_dict_field_in_value_object(test_domain):
+    test_domain.register(Audit)
+
+    audit_repo = test_domain.repository_for(Audit)
+    audit = Audit(permission=Permission(dict_object={"foo": "bar"}))
+    audit_repo.add(audit)
+
+    assert test_domain.get_dao(Audit).get(audit.id).permission_dict_object == {
+        "foo": "bar"
+    }