added mypy checks and some typehint changes to conform

.gitignore

@@ -1,6 +1,7 @@
 p38venv
 .idea
 .pytest_cache
+.mypy_cache
 *.pyc
 *.log
 test.db

mypy.ini

@@ -0,0 +1,5 @@
+[mypy]
+python_version = 3.8
+
+[mypy-sqlalchemy.*]
+ignore_missing_imports = True

ormar/fields/base.py

@@ -1,7 +1,8 @@
-from typing import Any, List, Optional, TYPE_CHECKING, Union
+from typing import Any, List, Optional, TYPE_CHECKING, Union, Type
 
 import sqlalchemy
 from pydantic import Field, typing
+from pydantic.fields import FieldInfo
 
 from ormar import ModelDefinitionError  # noqa I101
 
@@ -15,6 +16,7 @@ class BaseField:
 
     column_type: sqlalchemy.Column
     constraints: List = []
+    name: str
 
     primary_key: bool
     autoincrement: bool
@@ -24,12 +26,14 @@ class BaseField:
     pydantic_only: bool
     virtual: bool = False
     choices: typing.Sequence
+    to: Type["Model"]
+    through: Type["Model"]
 
     default: Any
     server_default: Any
 
     @classmethod
-    def default_value(cls) -> Optional[Field]:
+    def default_value(cls) -> Optional[FieldInfo]:
         if cls.is_auto_primary_key():
             return Field(default=None)
         if cls.has_default():

ormar/fields/foreign_key.py

@@ -1,4 +1,4 @@
-from typing import Any, Callable, List, Optional, TYPE_CHECKING, Type, Union
+from typing import Any, List, Optional, TYPE_CHECKING, Type, Union, Generator
 
 import sqlalchemy
 
@@ -7,7 +7,7 @@ from ormar.exceptions import RelationshipInstanceError
 from ormar.fields.base import BaseField
 
 if TYPE_CHECKING:  # pragma no cover
-    from ormar.models import Model
+    from ormar.models import Model, NewBaseModel
 
 
 def create_dummy_instance(fk: Type["Model"], pk: Any = None) -> "Model":
@@ -32,7 +32,7 @@ def ForeignKey(  # noqa CFQ002
         virtual: bool = False,
         onupdate: str = None,
         ondelete: str = None,
-) -> Type[object]:
+) -> Type["ForeignKeyField"]:
     fk_string = to.Meta.tablename + "." + to.Meta.pkname
     to_field = to.__fields__[to.Meta.pkname]
     namespace = dict(
@@ -65,7 +65,7 @@ class ForeignKeyField(BaseField):
     virtual: bool
 
     @classmethod
-    def __get_validators__(cls) -> Callable:
+    def __get_validators__(cls) -> Generator:
         yield cls.validate
 
     @classmethod
@@ -75,8 +75,8 @@ class ForeignKeyField(BaseField):
     @classmethod
     def _extract_model_from_sequence(
             cls, value: List, child: "Model", to_register: bool
-    ) -> Union["Model", List["Model"]]:
+    ) -> List["Model"]:
-        return [cls.expand_relationship(val, child, to_register) for val in value]
+        return [cls.expand_relationship(val, child, to_register) for val in value] # type: ignore
 
     @classmethod
     def _register_existing_model(
@@ -120,7 +120,7 @@ class ForeignKeyField(BaseField):
 
     @classmethod
     def expand_relationship(
-        cls, value: Any, child: "Model", to_register: bool = True
+            cls, value: Any, child: Union["Model", "NewBaseModel"], to_register: bool = True
     ) -> Optional[Union["Model", List["Model"]]]:
         if value is None:
             return None if not cls.virtual else []
@@ -131,7 +131,7 @@ class ForeignKeyField(BaseField):
             "list": cls._extract_model_from_sequence,
         }
 
-        model = constructors.get(
+        model = constructors.get( # type: ignore
             value.__class__.__name__, cls._construct_model_from_pk
         )(value, child, to_register)
         return model

ormar/fields/many_to_many.py

@@ -15,7 +15,7 @@ def ManyToMany(
     unique: bool = False,
     related_name: str = None,
     virtual: bool = False,
-) -> Type[object]:
+) -> Type["ManyToManyField"]:
     to_field = to.__fields__[to.Meta.pkname]
     namespace = dict(
         to=to,

ormar/fields/model_fields.py

@@ -18,10 +18,10 @@ def is_field_nullable(
 
 
 class ModelFieldFactory:
-    _bases = BaseField
+    _bases: Any = BaseField
-    _type = None
+    _type: Any = None
 
-    def __new__(cls, *args: Any, **kwargs: Any) -> Type[BaseField]:
+    def __new__(cls, *args: Any, **kwargs: Any) -> Type[BaseField]:  # type: ignore
         cls.validate(**kwargs)
 
         default = kwargs.pop("default", None)
@@ -58,7 +58,7 @@ class String(ModelFieldFactory):
     _bases = (pydantic.ConstrainedStr, BaseField)
     _type = str
 
-    def __new__(  # noqa CFQ002
+    def __new__(  # type: ignore # noqa CFQ002
         cls,
         *,
         allow_blank: bool = False,
@@ -68,7 +68,7 @@ class String(ModelFieldFactory):
         curtail_length: int = None,
         regex: str = None,
         **kwargs: Any
-    ) -> Type[str]:
+    ) -> Type[BaseField]:  # type: ignore
         kwargs = {
             **kwargs,
             **{
@@ -96,14 +96,14 @@ class Integer(ModelFieldFactory):
     _bases = (pydantic.ConstrainedInt, BaseField)
     _type = int
 
-    def __new__(
+    def __new__(  # type: ignore
         cls,
         *,
         minimum: int = None,
         maximum: int = None,
         multiple_of: int = None,
         **kwargs: Any
-    ) -> Type[int]:
+    ) -> Type[BaseField]:
         autoincrement = kwargs.pop("autoincrement", None)
         autoincrement = (
             autoincrement
@@ -131,9 +131,9 @@ class Text(ModelFieldFactory):
     _bases = (pydantic.ConstrainedStr, BaseField)
     _type = str
 
-    def __new__(
+    def __new__(  # type: ignore
         cls, *, allow_blank: bool = False, strip_whitespace: bool = False, **kwargs: Any
-    ) -> Type[str]:
+    ) -> Type[BaseField]:
         kwargs = {
             **kwargs,
             **{
@@ -153,14 +153,14 @@ class Float(ModelFieldFactory):
     _bases = (pydantic.ConstrainedFloat, BaseField)
     _type = float
 
-    def __new__(
+    def __new__(  # type: ignore
         cls,
         *,
         minimum: float = None,
         maximum: float = None,
         multiple_of: int = None,
         **kwargs: Any
-    ) -> Type[int]:
+    ) -> Type[BaseField]:
         kwargs = {
             **kwargs,
             **{
@@ -236,7 +236,7 @@ class Decimal(ModelFieldFactory):
     _bases = (pydantic.ConstrainedDecimal, BaseField)
     _type = decimal.Decimal
 
-    def __new__(  # noqa CFQ002
+    def __new__(  # type: ignore # noqa CFQ002
         cls,
         *,
         minimum: float = None,
@@ -247,7 +247,7 @@ class Decimal(ModelFieldFactory):
         max_digits: int = None,
         decimal_places: int = None,
         **kwargs: Any
-    ) -> Type[decimal.Decimal]:
+    ) -> Type[BaseField]:
         kwargs = {
             **kwargs,
             **{

ormar/models/metaclass.py

@@ -28,15 +28,19 @@ class ModelMeta:
     database: databases.Database
     columns: List[sqlalchemy.Column]
     pkname: str
-    model_fields: Dict[str, Union[BaseField, ForeignKey]]
+    model_fields: Dict[
+        str, Union[Type[BaseField], Type[ForeignKeyField], Type[ManyToManyField]]
+    ]
     alias_manager: AliasManager
 
 
-def register_relation_on_build(table_name: str, field: ForeignKey) -> None:
+def register_relation_on_build(table_name: str, field: Type[ForeignKeyField]) -> None:
     alias_manager.add_relation_type(field.to.Meta.tablename, table_name)
 
 
-def register_many_to_many_relation_on_build(table_name: str, field: ManyToMany) -> None:
+def register_many_to_many_relation_on_build(
+    table_name: str, field: Type[ManyToManyField]
+) -> None:
     alias_manager.add_relation_type(field.through.Meta.tablename, table_name)
     alias_manager.add_relation_type(
         field.through.Meta.tablename, field.to.Meta.tablename
@@ -106,7 +110,7 @@ def create_pydantic_field(
 ) -> None:
     model_field.through.__fields__[field_name] = ModelField(
         name=field_name,
-        type_=Optional[model],
+        type_=model,
         model_config=model.__config__,
         required=False,
         class_validators={},
@@ -130,7 +134,7 @@ def create_and_append_m2m_fk(
 
 
 def check_pk_column_validity(
-    field_name: str, field: BaseField, pkname: str
+    field_name: str, field: BaseField, pkname: Optional[str]
 ) -> Optional[str]:
     if pkname is not None:
         raise ModelDefinitionError("Only one primary key column is allowed.")
@@ -218,6 +222,7 @@ def populate_meta_tablename_columns_and_pk(
 ) -> Type["Model"]:
     tablename = name.lower() + "s"
     new_model.Meta.tablename = new_model.Meta.tablename or tablename
+    pkname: Optional[str]
 
     if hasattr(new_model.Meta, "columns"):
         columns = new_model.Meta.table.columns
@@ -226,12 +231,13 @@ def populate_meta_tablename_columns_and_pk(
         pkname, columns = sqlalchemy_columns_from_model_fields(
             new_model.Meta.model_fields, new_model.Meta.tablename
         )
+
+    if pkname is None:
+        raise ModelDefinitionError("Table has to have a primary key.")
+
     new_model.Meta.columns = columns
     new_model.Meta.pkname = pkname
 
-    if not new_model.Meta.pkname:
-        raise ModelDefinitionError("Table has to have a primary key.")
-
     return new_model
 
 
@@ -253,8 +259,8 @@ def get_pydantic_base_orm_config() -> Type[BaseConfig]:
     return Config
 
 
-def check_if_field_has_choices(field: BaseField) -> bool:
+def check_if_field_has_choices(field: Type[BaseField]) -> bool:
-    return hasattr(field, "choices") and field.choices
+    return hasattr(field, "choices") and bool(field.choices)
 
 
 def model_initialized_and_has_model_fields(model: Type["Model"]) -> bool:
@@ -287,7 +293,7 @@ def populate_choices_validators(  # noqa CCR001
 
 
 class ModelMetaclass(pydantic.main.ModelMetaclass):
-    def __new__(mcs: type, name: str, bases: Any, attrs: dict) -> type:
+    def __new__(mcs: "ModelMetaclass", name: str, bases: Any, attrs: dict) -> "ModelMetaclass":  # type: ignore
         attrs["Config"] = get_pydantic_base_orm_config()
         attrs["__name__"] = name
         attrs = extract_annotations_and_default_vals(attrs, bases)
@@ -306,7 +312,7 @@ class ModelMetaclass(pydantic.main.ModelMetaclass):
                 field_name = new_model.Meta.pkname
                 field = Integer(name=field_name, primary_key=True)
                 attrs["__annotations__"][field_name] = field
-                populate_default_pydantic_field_value(field, field_name, attrs)
+                populate_default_pydantic_field_value(field, field_name, attrs)  # type: ignore
 
             new_model = super().__new__(  # type: ignore
                 mcs, name, bases, attrs

ormar/models/model.py

@@ -1,5 +1,5 @@
 import itertools
-from typing import Any, List, Tuple, Union
+from typing import Any, List, Dict, Optional
 
 import sqlalchemy
 from databases.backends.postgres import Record
@@ -9,8 +9,8 @@ from ormar.fields.many_to_many import ManyToManyField
 from ormar.models import NewBaseModel  # noqa I100
 
 
-def group_related_list(list_: List) -> dict:
+def group_related_list(list_: List) -> Dict:
-    test_dict = dict()
+    test_dict: Dict[str, Any] = dict()
     grouped = itertools.groupby(list_, key=lambda x: x.split("__")[0])
     for key, group in grouped:
         group_list = list(group)
@@ -34,9 +34,9 @@ class Model(NewBaseModel):
             select_related: List = None,
             related_models: Any = None,
             previous_table: str = None,
-    ) -> Union["Model", Tuple["Model", dict]]:
+    ) -> Optional["Model"]:
 
-        item = {}
+        item: Dict[str, Any] = {}
         select_related = select_related or []
         related_models = related_models or []
         if select_related:
@@ -52,9 +52,12 @@ class Model(NewBaseModel):
                 previous_table
             ].through.Meta.tablename
 
+        if previous_table:
             table_prefix = cls.Meta.alias_manager.resolve_relation_join(
                 previous_table, cls.Meta.table.name
             )
+        else:
+            table_prefix = ''
         previous_table = cls.Meta.table.name
 
         item = cls.populate_nested_models_from_row(
@@ -106,7 +109,7 @@ class Model(NewBaseModel):
     async def save(self) -> "Model":
         self_fields = self._extract_model_db_fields()
 
-        if not self.pk and self.Meta.model_fields.get(self.Meta.pkname).autoincrement:
+        if not self.pk and self.Meta.model_fields[self.Meta.pkname].autoincrement:
             self_fields.pop(self.Meta.pkname, None)
         self_fields = self.objects._populate_default_values(self_fields)
         expr = self.Meta.table.insert()
@@ -138,5 +141,7 @@ class Model(NewBaseModel):
     async def load(self) -> "Model":
         expr = self.Meta.table.select().where(self.pk_column == self.pk)
         row = await self.Meta.database.fetch_one(expr)
+        if not row:  # pragma nocover
+            raise ValueError('Instance was deleted from database and cannot be refreshed')
         self.from_dict(dict(row))
         return self

ormar/models/modelproxy.py

@@ -1,5 +1,5 @@
 import inspect
-from typing import List, Optional, Set, TYPE_CHECKING, Type, TypeVar, Union
+from typing import List, Optional, Set, TYPE_CHECKING, Type, TypeVar, Union, Dict
 
 import ormar
 from ormar.exceptions import RelationshipInstanceError
@@ -9,6 +9,7 @@ from ormar.models.metaclass import ModelMeta
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model
+    from ormar.models import NewBaseModel
 
 Field = TypeVar("Field", bound=BaseField)
 
@@ -17,10 +18,10 @@ class ModelTableProxy:
     if TYPE_CHECKING:  # pragma no cover
         Meta: ModelMeta
 
-    def dict():  # noqa A003
+    def dict(self):  # noqa A003
         raise NotImplementedError  # pragma no cover
 
-    def _extract_own_model_fields(self) -> dict:
+    def _extract_own_model_fields(self) -> Dict:
         related_names = self.extract_related_names()
         self_fields = {k: v for k, v in self.dict().items() if k not in related_names}
         return self_fields
@@ -34,7 +35,7 @@ class ModelTableProxy:
         return self_fields
 
     @classmethod
-    def substitute_models_with_pks(cls, model_dict: dict) -> dict:
+    def substitute_models_with_pks(cls, model_dict: Dict) -> Dict:
         for field in cls.extract_related_names():
             field_value = model_dict.get(field, None)
             if field_value is not None:
@@ -80,7 +81,7 @@ class ModelTableProxy:
                 related_names.add(name)
         return related_names
 
-    def _extract_model_db_fields(self) -> dict:
+    def _extract_model_db_fields(self) -> Dict:
         self_fields = self._extract_own_model_fields()
         self_fields = {
             k: v for k, v in self_fields.items() if k in self.Meta.table.columns
@@ -92,7 +93,9 @@ class ModelTableProxy:
         return self_fields
 
     @staticmethod
-    def resolve_relation_name(item: "Model", related: "Model") -> Optional[str]:
+    def resolve_relation_name(
+        item: Union["NewBaseModel", Type["NewBaseModel"]], related: Union["NewBaseModel", Type["NewBaseModel"]]
+    ) -> str:
         for name, field in item.Meta.model_fields.items():
             if issubclass(field, ForeignKeyField):
                 # fastapi is creating clones of response model
@@ -100,11 +103,14 @@ class ModelTableProxy:
                 # so we need to compare Meta too as this one is copied as is
                 if field.to == related.__class__ or field.to.Meta == related.Meta:
                     return name
+        raise ValueError(
+            f"No relation between {item.get_name()} and {related.get_name()}"
+        )  # pragma nocover
 
     @staticmethod
     def resolve_relation_field(
         item: Union["Model", Type["Model"]], related: Union["Model", Type["Model"]]
-    ) -> Type[Field]:
+    ) -> Union[Type[BaseField], Type[ForeignKeyField]]:
         name = ModelTableProxy.resolve_relation_name(item, related)
         to_field = item.Meta.model_fields.get(name)
         if not to_field:  # pragma no cover
@@ -116,7 +122,7 @@ class ModelTableProxy:
 
     @classmethod
     def merge_instances_list(cls, result_rows: List["Model"]) -> List["Model"]:
-        merged_rows = []
+        merged_rows: List["Model"] = []
         for index, model in enumerate(result_rows):
             if index > 0 and model.pk == merged_rows[-1].pk:
                 merged_rows[-1] = cls.merge_two_instances(model, merged_rows[-1])

ormar/models/newbasemodel.py

@@ -3,13 +3,13 @@ import uuid
 from typing import (
     AbstractSet,
     Any,
+    Callable,
     Dict,
     List,
     Mapping,
     Optional,
     TYPE_CHECKING,
     Type,
-    TypeVar,
     Union,
 )
 
@@ -39,7 +39,7 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
     __slots__ = ("_orm_id", "_orm_saved", "_orm")
 
     if TYPE_CHECKING:  # pragma no cover
-        __model_fields__: Dict[str, TypeVar[BaseField]]
+        __model_fields__: Dict[str, Type[BaseField]]
         __table__: sqlalchemy.Table
         __fields__: Dict[str, pydantic.fields.ModelField]
         __pydantic_model__: Type[BaseModel]
@@ -84,7 +84,7 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
             for k, v in kwargs.items()
         }
 
-        values, fields_set, validation_error = pydantic.validate_model(self, kwargs)
+        values, fields_set, validation_error = pydantic.validate_model(self, kwargs)  # type: ignore
         if validation_error and not pk_only:
             raise validation_error
 
@@ -134,13 +134,14 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
     ) -> Optional[Union["Model", List["Model"]]]:
         if item in self._orm:
             return self._orm.get(item)
+        return None
 
-    def __eq__(self, other: "Model") -> bool:
+    def __eq__(self, other: object) -> bool:
         if isinstance(other, NewBaseModel):
             return self.__same__(other)
         return super().__eq__(other)  # pragma no cover
 
-    def __same__(self, other: "Model") -> bool:
+    def __same__(self, other: "NewBaseModel") -> bool:
         return (
             self._orm_id == other._orm_id
             or self.dict() == other.dict()
@@ -205,19 +206,19 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
                 dict_instance[field] = None
         return dict_instance
 
-    def from_dict(self, value_dict: Dict) -> "Model":
+    def from_dict(self, value_dict: Dict) -> "NewBaseModel":
         for key, value in value_dict.items():
             setattr(self, key, value)
         return self
 
-    def _convert_json(self, column_name: str, value: Any, op: str) -> Union[str, dict]:
+    def _convert_json(self, column_name: str, value: Any, op: str) -> Union[str, Dict]:
         if not self._is_conversion_to_json_needed(column_name):
             return value
 
         condition = (
             isinstance(value, str) if op == "loads" else not isinstance(value, str)
         )
-        operand = json.loads if op == "loads" else json.dumps
+        operand: Callable[[Any], Any] = json.loads if op == "loads" else json.dumps
 
         if condition:
             try:
@@ -227,4 +228,4 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
         return value
 
     def _is_conversion_to_json_needed(self, column_name: str) -> bool:
-        return self.Meta.model_fields.get(column_name).__type__ == pydantic.Json
+        return self.Meta.model_fields[column_name].__type__ == pydantic.Json

ormar/queryset/clause.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional, TYPE_CHECKING, Tuple, Type, Union
+from typing import Any, Dict, List, Optional, TYPE_CHECKING, Tuple, Type
 
 import sqlalchemy
 from sqlalchemy import text
@@ -118,7 +118,7 @@ class QueryClause:
 
     def _determine_filter_target_table(
         self, related_parts: List[str], select_related: List[str]
-    ) -> Tuple[List[str], str, "Model"]:
+    ) -> Tuple[List[str], str, Type["Model"]]:
 
         table_prefix = ""
         model_cls = self.model_cls
@@ -168,9 +168,7 @@ class QueryClause:
         return clause
 
     @staticmethod
-    def _escape_characters_in_clause(
+    def _escape_characters_in_clause(op: str, value: Any) -> Tuple[Any, bool]:
-        op: str, value: Union[str, "Model"]
-    ) -> Tuple[str, bool]:
         has_escaped_character = False
 
         if op not in [

ormar/queryset/join.py

@@ -22,8 +22,8 @@ class SqlJoin:
         self,
         used_aliases: List,
         select_from: sqlalchemy.sql.select,
-        order_bys: List,
+        order_bys: List[sqlalchemy.sql.elements.TextClause],
-        columns: List,
+        columns: List[sqlalchemy.Column],
     ) -> None:
         self.used_aliases = used_aliases
         self.select_from = select_from

ormar/queryset/limit_query.py

@@ -1,8 +1,10 @@
+from typing import Optional
+
 import sqlalchemy
 
 
 class LimitQuery:
-    def __init__(self, limit_count: int) -> None:
+    def __init__(self, limit_count: Optional[int]) -> None:
         self.limit_count = limit_count
 
     def apply(self, expr: sqlalchemy.sql.select) -> sqlalchemy.sql.select:

ormar/queryset/offset_query.py

@@ -1,8 +1,10 @@
+from typing import Optional
+
 import sqlalchemy
 
 
 class OffsetQuery:
-    def __init__(self, query_offset: int) -> None:
+    def __init__(self, query_offset: Optional[int]) -> None:
         self.query_offset = query_offset
 
     def apply(self, expr: sqlalchemy.sql.select) -> sqlalchemy.sql.select:

ormar/queryset/query.py

@@ -1,4 +1,4 @@
-from typing import List, TYPE_CHECKING, Tuple, Type
+from typing import List, TYPE_CHECKING, Tuple, Type, Optional
 
 import sqlalchemy
 from sqlalchemy import text
@@ -18,8 +18,8 @@ class Query:
         filter_clauses: List,
         exclude_clauses: List,
         select_related: List,
-        limit_count: int,
+        limit_count: Optional[int],
-        offset: int,
+        offset: Optional[int],
     ) -> None:
         self.query_offset = offset
         self.limit_count = limit_count
@@ -30,11 +30,11 @@ class Query:
         self.model_cls = model_cls
         self.table = self.model_cls.Meta.table
 
-        self.used_aliases = []
+        self.used_aliases: List[str] = []
 
-        self.select_from = None
+        self.select_from: List[str] = []
-        self.columns = None
+        self.columns = [sqlalchemy.Column]
-        self.order_bys = None
+        self.order_bys: List[sqlalchemy.sql.elements.TextClause] = []
 
     @property
     def prefixed_pk_name(self) -> str:
@@ -89,7 +89,7 @@ class Query:
         return expr
 
     def _reset_query_parameters(self) -> None:
-        self.select_from = None
+        self.select_from = []
-        self.columns = None
+        self.columns = []
-        self.order_bys = None
+        self.order_bys = []
         self.used_aliases = []

ormar/queryset/queryset.py

@@ -1,4 +1,4 @@
-from typing import Any, List, Mapping, TYPE_CHECKING, Tuple, Type, Union
+from typing import Any, List, Mapping, TYPE_CHECKING, Type, Union, Optional
 
 import databases
 import sqlalchemy
@@ -13,6 +13,7 @@ from ormar.queryset.query import Query
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model
+    from ormar.models.metaclass import ModelMeta
 
 
 class QuerySet:
@@ -36,23 +37,36 @@ class QuerySet:
     def __get__(self, instance: "QuerySet", owner: Type["Model"]) -> "QuerySet":
         return self.__class__(model_cls=owner)
 
-    def _process_query_result_rows(self, rows: List[Mapping]) -> List["Model"]:
+    @property
+    def model_meta(self) -> "ModelMeta":
+        if not self.model_cls:  # pragma nocover
+            raise ValueError("Model class of QuerySet is not initialized")
+        return self.model_cls.Meta
+
+    @property
+    def model(self) -> Type["Model"]:
+        if not self.model_cls:  # pragma nocover
+            raise ValueError("Model class of QuerySet is not initialized")
+        return self.model_cls
+
+    def _process_query_result_rows(self, rows: List) -> List[Optional["Model"]]:
         result_rows = [
-            self.model_cls.from_row(row, select_related=self._select_related)
+            self.model.from_row(row, select_related=self._select_related)
             for row in rows
         ]
-        rows = self.model_cls.merge_instances_list(result_rows)
+        if result_rows:
-        return rows
+            return self.model.merge_instances_list(result_rows)  # type: ignore
+        return result_rows
 
     def _populate_default_values(self, new_kwargs: dict) -> dict:
-        for field_name, field in self.model_cls.Meta.model_fields.items():
+        for field_name, field in self.model_meta.model_fields.items():
             if field_name not in new_kwargs and field.has_default():
                 new_kwargs[field_name] = field.get_default()
         return new_kwargs
 
     def _remove_pk_from_kwargs(self, new_kwargs: dict) -> dict:
-        pkname = self.model_cls.Meta.pkname
+        pkname = self.model_meta.pkname
-        pk = self.model_cls.Meta.model_fields[pkname]
+        pk = self.model_meta.model_fields[pkname]
         if new_kwargs.get(pkname, ormar.Undefined) is None and (
                 pk.nullable or pk.autoincrement
         ):
@@ -60,23 +74,23 @@ class QuerySet:
         return new_kwargs
 
     @staticmethod
-    def check_single_result_rows_count(rows: List["Model"]) -> None:
+    def check_single_result_rows_count(rows: List[Optional["Model"]]) -> None:
-        if not rows:
+        if not rows or rows[0] is None:
             raise NoMatch()
         if len(rows) > 1:
             raise MultipleMatches()
 
     @property
     def database(self) -> databases.Database:
-        return self.model_cls.Meta.database
+        return self.model_meta.database
 
     @property
     def table(self) -> sqlalchemy.Table:
-        return self.model_cls.Meta.table
+        return self.model_meta.table
 
     def build_select_expression(self) -> sqlalchemy.sql.select:
         qry = Query(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             select_related=self._select_related,
             filter_clauses=self.filter_clauses,
             exclude_clauses=self.exclude_clauses,
@@ -89,7 +103,7 @@ class QuerySet:
 
     def filter(self, _exclude: bool = False, **kwargs: Any) -> "QuerySet":  # noqa: A003
         qryclause = QueryClause(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             select_related=self._select_related,
             filter_clauses=self.filter_clauses,
         )
@@ -102,7 +116,7 @@ class QuerySet:
             filter_clauses = filter_clauses
 
         return self.__class__(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             filter_clauses=filter_clauses,
             exclude_clauses=exclude_clauses,
             select_related=select_related,
@@ -113,13 +127,13 @@ class QuerySet:
     def exclude(self, **kwargs: Any) -> "QuerySet":  # noqa: A003
         return self.filter(_exclude=True, **kwargs)
 
-    def select_related(self, related: Union[List, Tuple, str]) -> "QuerySet":
+    def select_related(self, related: Union[List, str]) -> "QuerySet":
-        if not isinstance(related, (list, tuple)):
+        if not isinstance(related, list):
             related = [related]
 
         related = list(set(list(self._select_related) + related))
         return self.__class__(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             filter_clauses=self.filter_clauses,
             exclude_clauses=self.exclude_clauses,
             select_related=related,
@@ -138,7 +152,7 @@ class QuerySet:
         return await self.database.fetch_val(expr)
 
     async def update(self, each: bool = False, **kwargs: Any) -> int:
-        self_fields = self.model_cls.extract_db_own_fields()
+        self_fields = self.model.extract_db_own_fields()
         updates = {k: v for k, v in kwargs.items() if k in self_fields}
         if not each and not self.filter_clauses:
             raise QueryDefinitionError(
@@ -165,7 +179,7 @@ class QuerySet:
 
     def limit(self, limit_count: int) -> "QuerySet":
         return self.__class__(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             filter_clauses=self.filter_clauses,
             exclude_clauses=self.exclude_clauses,
             select_related=self._select_related,
@@ -175,7 +189,7 @@ class QuerySet:
 
     def offset(self, offset: int) -> "QuerySet":
         return self.__class__(
-            model_cls=self.model_cls,
+            model_cls=self.model,
             filter_clauses=self.filter_clauses,
             exclude_clauses=self.exclude_clauses,
             select_related=self._select_related,
@@ -189,7 +203,7 @@ class QuerySet:
 
         rows = await self.limit(1).all()
         self.check_single_result_rows_count(rows)
-        return rows[0]
+        return rows[0]  # type: ignore
 
     async def get(self, **kwargs: Any) -> "Model":
         if kwargs:
@@ -200,9 +214,9 @@ class QuerySet:
             expr = expr.limit(2)
 
         rows = await self.database.fetch_all(expr)
-        rows = self._process_query_result_rows(rows)
+        processed_rows = self._process_query_result_rows(rows)
-        self.check_single_result_rows_count(rows)
+        self.check_single_result_rows_count(processed_rows)
-        return rows[0]
+        return processed_rows[0] # type: ignore
 
     async def get_or_create(self, **kwargs: Any) -> "Model":
         try:
@@ -211,7 +225,7 @@ class QuerySet:
             return await self.create(**kwargs)
 
     async def update_or_create(self, **kwargs: Any) -> "Model":
-        pk_name = self.model_cls.Meta.pkname
+        pk_name = self.model_meta.pkname
         if "pk" in kwargs:
             kwargs[pk_name] = kwargs.pop("pk")
         if pk_name not in kwargs or kwargs.get(pk_name) is None:
@@ -219,7 +233,7 @@ class QuerySet:
         model = await self.get(pk=kwargs[pk_name])
         return await model.update(**kwargs)
 
-    async def all(self, **kwargs: Any) -> List["Model"]:  # noqa: A003
+    async def all(self, **kwargs: Any) -> List[Optional["Model"]]:  # noqa: A003
         if kwargs:
             return await self.filter(**kwargs).all()
 
@@ -233,20 +247,20 @@ class QuerySet:
 
         new_kwargs = dict(**kwargs)
         new_kwargs = self._remove_pk_from_kwargs(new_kwargs)
-        new_kwargs = self.model_cls.substitute_models_with_pks(new_kwargs)
+        new_kwargs = self.model.substitute_models_with_pks(new_kwargs)
         new_kwargs = self._populate_default_values(new_kwargs)
 
         expr = self.table.insert()
         expr = expr.values(**new_kwargs)
 
         # Execute the insert, and return a new model instance.
-        instance = self.model_cls(**kwargs)
+        instance = self.model(**kwargs)
         pk = await self.database.execute(expr)
-        pk_name = self.model_cls.Meta.pkname
+        pk_name = self.model_meta.pkname
         if pk_name not in kwargs and pk_name in new_kwargs:
-            instance.pk = new_kwargs[self.model_cls.Meta.pkname]
+            instance.pk = new_kwargs[self.model_meta.pkname]
-        if pk and isinstance(pk, self.model_cls.pk_type()):
+        if pk and isinstance(pk, self.model.pk_type()):
-            setattr(instance, self.model_cls.Meta.pkname, pk)
+            setattr(instance, self.model_meta.pkname, pk)
         return instance
 
     async def bulk_create(self, objects: List["Model"]) -> None:
@@ -254,7 +268,7 @@ class QuerySet:
         for objt in objects:
             new_kwargs = objt.dict()
             new_kwargs = self._remove_pk_from_kwargs(new_kwargs)
-            new_kwargs = self.model_cls.substitute_models_with_pks(new_kwargs)
+            new_kwargs = self.model.substitute_models_with_pks(new_kwargs)
             new_kwargs = self._populate_default_values(new_kwargs)
             ready_objects.append(new_kwargs)
 
@@ -265,10 +279,12 @@ class QuerySet:
             self, objects: List["Model"], columns: List[str] = None
     ) -> None:
         ready_objects = []
-        pk_name = self.model_cls.Meta.pkname
+        pk_name = self.model_meta.pkname
         if not columns:
-            columns = self.model_cls.extract_db_own_fields().union(
+            columns = list(
-                self.model_cls.extract_related_names()
+                self.model.extract_db_own_fields().union(
+                    self.model.extract_related_names()
+                )
             )
 
         if pk_name not in columns:
@@ -279,13 +295,13 @@ class QuerySet:
             if pk_name not in new_kwargs or new_kwargs.get(pk_name) is None:
                 raise QueryDefinitionError(
                     "You cannot update unsaved objects. "
-                    f"{self.model_cls.__name__} has to have {pk_name} filled."
+                    f"{self.model.__name__} has to have {pk_name} filled."
                 )
-            new_kwargs = self.model_cls.substitute_models_with_pks(new_kwargs)
+            new_kwargs = self.model.substitute_models_with_pks(new_kwargs)
             new_kwargs = {"new_" + k: v for k, v in new_kwargs.items() if k in columns}
             ready_objects.append(new_kwargs)
 
-        pk_column = self.model_cls.Meta.table.c.get(pk_name)
+        pk_column = self.model_meta.table.c.get(pk_name)
         expr = self.table.update().where(pk_column == bindparam("new_" + pk_name))
         expr = expr.values(
             **{k: bindparam("new_" + k) for k in columns if k != pk_name}

ormar/relations/alias_manager.py

@@ -1,7 +1,7 @@
 import string
 import uuid
 from random import choices
-from typing import List
+from typing import List, Dict
 
 import sqlalchemy
 from sqlalchemy import text
@@ -14,7 +14,7 @@ def get_table_alias() -> str:
 
 class AliasManager:
     def __init__(self) -> None:
-        self._aliases = dict()
+        self._aliases: Dict[str, str] = dict()
 
     @staticmethod
     def prefixed_columns(alias: str, table: sqlalchemy.Table) -> List[text]:

ormar/relations/querysetproxy.py

@@ -13,8 +13,8 @@ class QuerysetProxy:
         relation: "Relation"
 
     def __init__(self, relation: "Relation") -> None:
-        self.relation = relation
+        self.relation: Relation = relation
-        self.queryset = None
+        self.queryset: "QuerySet"
 
     def _assign_child_to_parent(self, child: "Model") -> None:
         owner = self.relation._owner

ormar/relations/relation.py

@@ -9,6 +9,7 @@ from ormar.relations.relation_proxy import RelationProxy
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model
     from ormar.relations import RelationsManager
+    from ormar.models import NewBaseModel
 
 
 class RelationType(Enum):
@@ -26,17 +27,19 @@ class Relation:
             through: Type["Model"] = None,
     ) -> None:
         self.manager = manager
-        self._owner = manager.owner
+        self._owner: "Model" = manager.owner
-        self._type = type_
+        self._type: RelationType = type_
-        self.to = to
+        self.to: Type["Model"] = to
-        self.through = through
+        self.through: Optional[Type["Model"]] = through
-        self.related_models = (
+        self.related_models: Optional[Union[RelationProxy, "Model"]] = (
             RelationProxy(relation=self)
             if type_ in (RelationType.REVERSE, RelationType.MULTIPLE)
             else None
         )
 
     def _find_existing(self, child: "Model") -> Optional[int]:
+        if not isinstance(self.related_models, RelationProxy):  # pragma nocover
+            raise ValueError("Cannot find existing models in parent relation type")
         for ind, relation_child in enumerate(self.related_models[:]):
             try:
                 if relation_child == child:
@@ -52,7 +55,7 @@ class Relation:
             self._owner.__dict__[relation_name] = child
         else:
             if self._find_existing(child) is None:
-                self.related_models.append(child)
+                self.related_models.append(child)  # type: ignore
                 rel = self._owner.__dict__.get(relation_name, [])
                 rel = rel or []
                 if not isinstance(rel, list):
@@ -60,19 +63,19 @@ class Relation:
                 rel.append(child)
                 self._owner.__dict__[relation_name] = rel
 
-    def remove(self, child: "Model") -> None:
+    def remove(self, child: Union["NewBaseModel", Type["NewBaseModel"]]) -> None:
         relation_name = self._owner.resolve_relation_name(self._owner, child)
         if self._type == RelationType.PRIMARY:
-            if self.related_models.__same__(child):
+            if self.related_models == child:
                 self.related_models = None
                 del self._owner.__dict__[relation_name]
         else:
             position = self._find_existing(child)
             if position is not None:
-                self.related_models.pop(position)
+                self.related_models.pop(position)  # type: ignore
                 del self._owner.__dict__[relation_name][position]
 
-    def get(self) -> Union[List["Model"], "Model"]:
+    def get(self) -> Optional[Union[List["Model"], "Model"]]:
         return self.related_models
 
     def __repr__(self) -> str:  # pragma no cover

ormar/relations/relation_manager.py

@@ -1,6 +1,7 @@
-from typing import List, Optional, TYPE_CHECKING, Type, Union
+from typing import List, Optional, TYPE_CHECKING, Type, Union, Dict
 from weakref import proxy
 
+from ormar.fields import BaseField
 from ormar.fields.foreign_key import ForeignKeyField
 from ormar.fields.many_to_many import ManyToManyField
 from ormar.relations.relation import Relation, RelationType
@@ -11,25 +12,28 @@ from ormar.relations.utils import (
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model
+    from ormar.models import NewBaseModel
 
 
 class RelationsManager:
     def __init__(
-        self, related_fields: List[Type[ForeignKeyField]] = None, owner: "Model" = None
+            self,
+            related_fields: List[Type[ForeignKeyField]] = None,
+            owner: "NewBaseModel" = None,
     ) -> None:
         self.owner = proxy(owner)
         self._related_fields = related_fields or []
         self._related_names = [field.name for field in self._related_fields]
-        self._relations = dict()
+        self._relations: Dict[str, Relation] = dict()
         for field in self._related_fields:
             self._add_relation(field)
 
-    def _get_relation_type(self, field: Type[ForeignKeyField]) -> RelationType:
+    def _get_relation_type(self, field: Type[BaseField]) -> RelationType:
         if issubclass(field, ManyToManyField):
             return RelationType.MULTIPLE
         return RelationType.PRIMARY if not field.virtual else RelationType.REVERSE
 
-    def _add_relation(self, field: Type[ForeignKeyField]) -> None:
+    def _add_relation(self, field: Type[BaseField]) -> None:
         self._relations[field.name] = Relation(
             manager=self,
             type_=self._get_relation_type(field),
@@ -44,15 +48,17 @@ class RelationsManager:
         relation = self._relations.get(name, None)
         if relation is not None:
             return relation.get()
+        return None  # pragma nocover
 
     def _get(self, name: str) -> Optional[Relation]:
         relation = self._relations.get(name, None)
         if relation is not None:
             return relation
+        return None
 
     @staticmethod
     def add(parent: "Model", child: "Model", child_name: str, virtual: bool) -> None:
-        to_field = child.resolve_relation_field(child, parent)
+        to_field: Type[BaseField] = child.resolve_relation_field(child, parent)
 
         (parent, child, child_name, to_name,) = get_relations_sides_and_names(
             to_field, parent, child, child_name, virtual
@@ -61,18 +67,22 @@ class RelationsManager:
         parent_relation = parent._orm._get(child_name)
         if not parent_relation:
             parent_relation = register_missing_relation(parent, child, child_name)
-        parent_relation.add(child)
+        parent_relation.add(child)  # type: ignore
-        child._orm._get(to_name).add(parent)
 
-    def remove(self, name: str, child: "Model") -> None:
+        child_relation = child._orm._get(to_name)
+        if child_relation:
+            child_relation.add(parent)
+
+    def remove(self, name: str, child: Union["NewBaseModel", Type["NewBaseModel"]]) -> None:
         relation = self._get(name)
+        if relation:
             relation.remove(child)
 
     @staticmethod
-    def remove_parent(item: "Model", name: Union[str, "Model"]) -> None:
+    def remove_parent(item: Union["NewBaseModel", Type["NewBaseModel"]], name: "Model") -> None:
         related_model = name
-        name = item.resolve_relation_name(item, related_model)
+        rel_name = item.resolve_relation_name(item, related_model)
-        if name in item._orm:
+        if rel_name in item._orm:
             relation_name = item.resolve_relation_name(related_model, item)
-            item._orm.remove(name, related_model)
+            item._orm.remove(rel_name, related_model)
             related_model._orm.remove(relation_name, item)

ormar/relations/relation_proxy.py

@@ -13,22 +13,30 @@ if TYPE_CHECKING:  # pragma no cover
 class RelationProxy(list):
     def __init__(self, relation: "Relation") -> None:
         super(RelationProxy, self).__init__()
-        self.relation = relation
+        self.relation: Relation = relation
-        self._owner = self.relation.manager.owner
+        self._owner: "Model" = self.relation.manager.owner
         self.queryset_proxy = QuerysetProxy(relation=self.relation)
 
     def __getattribute__(self, item: str) -> Any:
         if item in ["count", "clear"]:
-            if not self.queryset_proxy.queryset:
+            self._initialize_queryset()
-                self.queryset_proxy.queryset = self._set_queryset()
             return getattr(self.queryset_proxy, item)
         return super().__getattribute__(item)
 
     def __getattr__(self, item: str) -> Any:
-        if not self.queryset_proxy.queryset:
+        self._initialize_queryset()
-            self.queryset_proxy.queryset = self._set_queryset()
         return getattr(self.queryset_proxy, item)
 
+    def _initialize_queryset(self) -> None:
+        if not self._check_if_queryset_is_initialized():
+            self.queryset_proxy.queryset = self._set_queryset()
+
+    def _check_if_queryset_is_initialized(self) -> bool:
+        return (
+            hasattr(self.queryset_proxy, "queryset")
+            and self.queryset_proxy.queryset is not None
+        )
+
     def _set_queryset(self) -> "QuerySet":
         owner_table = self.relation._owner.Meta.tablename
         pkname = self.relation._owner.Meta.pkname
@@ -45,10 +53,15 @@ class RelationProxy(list):
         )
         return queryset
 
-    async def remove(self, item: "Model") -> None:
+    async def remove(self, item: "Model") -> None:  # type: ignore
         super().remove(item)
         rel_name = item.resolve_relation_name(item, self._owner)
-        item._orm._get(rel_name).remove(self._owner)
+        relation = item._orm._get(rel_name)
+        if relation is None:  # pragma nocover
+            raise ValueError(
+                f"{self._owner.get_name()} does not have relation {rel_name}"
+            )
+        relation.remove(self._owner)
         if self.relation._type == ormar.RelationType.MULTIPLE:
             await self.queryset_proxy.delete_through_instance(item)
 

ormar/relations/utils.py

@@ -1,8 +1,8 @@
-from typing import TYPE_CHECKING, Tuple, Type
+from typing import TYPE_CHECKING, Tuple, Type, Optional
 from weakref import proxy
 
 import ormar
-from ormar.fields.foreign_key import ForeignKeyField
+from ormar.fields import BaseField
 from ormar.fields.many_to_many import ManyToManyField
 from ormar.relations import Relation
 
@@ -12,7 +12,7 @@ if TYPE_CHECKING:  # pragma no cover
 
 def register_missing_relation(
     parent: "Model", child: "Model", child_name: str
-) -> Relation:
+) -> Optional[Relation]:
     ormar.models.expand_reverse_relationships(child.__class__)
     name = parent.resolve_relation_name(parent, child)
     field = parent.Meta.model_fields[name]
@@ -22,7 +22,7 @@ def register_missing_relation(
 
 
 def get_relations_sides_and_names(
-    to_field: Type[ForeignKeyField],
+    to_field: Type[BaseField],
     parent: "Model",
     child: "Model",
     child_name: str,