Add comments to pydantic code (#123)

src/blueapi/utils/type_validator.py

@@ -125,7 +125,7 @@ def create_model_with_type_validators(
     Args:
         name: Name of the new model
         definitions: Definitions of how to validate which types of field
-        base (Type[BaseModel]): Base class for the model
+        base: Base class for the model
 
     Returns:
         Type[BaseModel]: A new version of `base` with type validators
@@ -142,7 +142,6 @@ def create_model_with_type_validators(
     base: Optional[Type[BaseModel]] = None,
     func: Optional[Callable[..., Any]] = None,
     config: Optional[Type[BaseConfig]] = None,
-    cache: Optional[Dict[Type, Type]] = None,
 ) -> Type[BaseModel]:
     """
     Create a pydantic model with type validators according to
@@ -164,24 +163,17 @@ def create_model_with_type_validators(
         Type[BaseModel]: A new pydantic model
     """
 
-    cache = cache or {}
+    # Fields are determined from various sources, directly passed, a base class
+    # and/or a function signature.
     all_fields = {**(fields or {})}
     if base is not None:
         all_fields = {**all_fields, **_extract_fields_from_model(base)}
     if func is not None:
         all_fields = {**all_fields, **_extract_fields_from_function(func)}
     for name, field in all_fields.items():
         annotation, val = field
-        if annotation in cache:
-            all_fields[name] = cache[annotation], val
-        else:
-            all_fields[name] = apply_type_validators(annotation, definitions), val
-        # model_type = find_model_type(annotation)
-        # if model_type is not None:
-        #     recursed = create_model_with_type_validators(
-        #         annotation.__name__, definitions, base=model_type
-        #     )
-        #     all_fields[name] = recursed, val
+        all_fields[name] = apply_type_validators(annotation, definitions), val
+
     validators = _type_validators(all_fields, definitions)
     return create_model(  # type: ignore
         name, **all_fields, __base__=base, __validators__=validators, __config__=config
@@ -191,16 +183,24 @@ def create_model_with_type_validators(
 def apply_type_validators(
     model_type: Type,
     definitions: List[TypeValidatorDefinition],
-    cache: Optional[Dict[Type, Type]] = None,
 ) -> Type:
-    cache = cache or {}
-    if model_type in cache:
-        return cache[model_type]
+    """
+    Create a copy of a model (or modellable type) that has the defined
+    type validators.
+
+    Args:
+        model_type: The model to copy (e.g. a BaseModel or pydantic dataclass)
+        definitions: Definitions of type validators that the copy should have
+
+    Returns:
+        Type: A new pydantic model
+    """
 
     if isclass(model_type) and issubclass(model_type, BaseModel):
         if "__root__" in model_type.__fields__:
             return apply_type_validators(
-                model_type.__fields__["__root__"].type_, definitions, cache=cache
+                model_type.__fields__["__root__"].type_,
+                definitions,
             )
         else:
             return create_model_with_type_validators(
@@ -210,14 +210,26 @@ def apply_type_validators(
             )
     elif isclass(model_type) and hasattr(model_type, "__pydantic_model__"):
         model = getattr(model_type, "__pydantic_model__")
-        return apply_type_validators(model, definitions, cache=cache)
+        # Recursively apply to inner model
+        return apply_type_validators(
+            model,
+            definitions,
+        )
     else:
+        # Apply to type parameters, e.g. apply to int in List[int]
         params = [
-            apply_type_validators(param, definitions, cache=cache)
+            apply_type_validators(
+                param,
+                definitions,
+            )
             for param in get_args(model_type)
         ]
+
+        # __origin__ converts Union[int, str] to Union
         if params and hasattr(model_type, "__origin__"):
             origin = getattr(model_type, "__origin__")
+            # Certain origins are different to their code notations,
+            # e.g. list vs List.
             origin = _sanitise_origin(origin)
             return origin[tuple(params)]
     return model_type
@@ -304,17 +316,57 @@ def _determine_fields_of_type(fields: Fields, field_type: Type) -> Iterable[str]
 
 
 def is_type_or_container_type(type_to_check: Type, field_type: Type) -> bool:
+    """
+    Is the supplied type either the type to check against or a type that
+    contains it?
+    For example, if field_type=int, then this should return True if type_to_check
+    is int, List[int], Dict[str, int], Set[int] etc.
+
+    Args:
+        type_to_check: The type to check
+        field_type: The expected type
+
+    Returns:
+        bool: True if the types match
+    """
     return params_contains(type_to_check, field_type)
 
 
 def params_contains(type_to_check: Type, field_type: Type) -> bool:
+    """
+    Do the parameters of a type contain the type to check?
+    For example, do the parameters of List[int] conain int? Yes
+
+    Args:
+        type_to_check: The type to check
+        field_type: The expected type
+
+    Returns:
+        bool: True if the types match
+    """
+
     type_params = get_args(type_to_check)
     return type_to_check is field_type or any(
         map(lambda v: params_contains(v, field_type), type_params)
     )
 
 
 def apply_to_scalars(func: Callable[[T], U], obj: Any) -> Any:
+    """
+    Apply the supplied function to all scalars within the JSON-serializable
+    object. In this case, scalars are values of type int, str, float, and bool.
+    For example, if the function multiplies by 2 and the object is:
+    {"a": 3, "b": [4, 5]} then the result should be {"a": 6, "b": [8, 10]}
+
+    Args:
+        func: The function to apply.
+        obj: An object that can be serialized to JSON
+
+    Returns:
+        Any: A new JSON-serializable object with the function
+            applied to all scalars.
+    """
+
     if is_list_type(obj):
         return list(map(lambda v: apply_to_scalars(func, v), obj))
     elif is_dict_type(obj):