Simplify IncorrectUsageError exception

docs/guides/change-state/commands.md

@@ -81,9 +81,6 @@ Out[3]: <PublishArticle: PublishArticle object ({'article_id': '1', 'published_a
 
 In [4]: publish_article_command.published_at = datetime.now() - timedelta(hours=24)
 ...
-IncorrectUsageError: {
-    '_command': [
-        'Command Objects are immutable and cannot be modified once created'
-    ]
+IncorrectUsageError: 'Command Objects are immutable and cannot be modified once created'
 }
 ```

docs/guides/domain-definition/entities.md

@@ -33,7 +33,7 @@ specified while defining the identity, you will see an `IncorrectUsageError`:
 ... class Comment:
 ...     content = String(max_length=500)
 ... 
-IncorrectUsageError: {'_entity': ['Entity `Comment` needs to be associated with an Aggregate']}
+IncorrectUsageError: 'Entity `Comment` needs to be associated with an Aggregate'
 ```
 
 An Entity cannot enclose another Entity (or Aggregate). Trying to do so will
@@ -44,7 +44,7 @@ throw `IncorrectUsageError`.
 ... class SubComment:
 ...     parent = Comment()
 ... 
-IncorrectUsageError: {'_entity': ['Entity `Comment` needs to be associated with an Aggregate']}
+IncorrectUsageError: 'Entity `Comment` needs to be associated with an Aggregate'
 ```
 <!-- FIXME Ensure entities cannot enclose other entities. When entities
 enclose something other than permitted fields, through an error-->

docs/guides/domain-definition/events.md

@@ -195,9 +195,5 @@ In [2]: renamed = UserRenamed(user_id=user.id, name="John Doe Jr.")
 
 In [3]: renamed.name = "John Doe Sr."
 ...
-IncorrectUsageError: {
-    '_message': [
-        'Event/Command Objects are immutable and cannot be modified once created'
-    ]
-}
+IncorrectUsageError: 'Event/Command Objects are immutable and cannot be modified once created'
 ```

docs/guides/domain-definition/value-objects.md

@@ -228,7 +228,7 @@ In [3]: class Balance(BaseValueObject):
    ...:     currency = String(max_length=3, unique=True)
    ...:     amount = Float()
 ...
-IncorrectUsageError: {'_value_object': ["Value Objects cannot contain fields marked 'unique' (field 'currency')"]}
+IncorrectUsageError: "Value Objects cannot contain fields marked 'unique' (field 'currency')"
 ```
 
 Same case if you try to find a Value Object's `id_field`:
@@ -238,7 +238,7 @@ In [4]: from protean.reflection import id_field
 
 In [5]: id_field(Balance)
 ...
-IncorrectUsageError: {"identity": ["<class '__main__.Balance'> does not have identity fields"]}
+IncorrectUsageError: "<class '__main__.Balance'> does not have identity fields"
 ```
 
 ## Immutability
@@ -250,5 +250,5 @@ In [1]: bal1 = Balance(currency='USD', amount=100.0)
 
 In [2]: bal1.currency = "CAD"
 ...
-IncorrectUsageError: {'_value_object': ["Value Objects are immutable and cannot be modified once created"]}
+IncorrectUsageError: "Value Objects are immutable and cannot be modified once created"
 ```

src/protean/core/aggregate.py

@@ -257,11 +257,7 @@ def apply(fn):
 
     if len(typing.get_type_hints(fn)) > 2:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Handler method `{fn.__name__}` has incorrect number of arguments"
-                ]
-            }
+            f"Handler method `{fn.__name__}` has incorrect number of arguments"
         )
 
     try:
@@ -276,11 +272,7 @@ def apply(fn):
         )
     except StopIteration:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Apply method `{fn.__name__}` should accept an argument annotated with the Event class"
-                ]
-            }
+            f"Apply method `{fn.__name__}` should accept an argument annotated with the Event class"
         )
 
     @functools.wraps(fn)

src/protean/core/command.py

@@ -59,11 +59,7 @@ def command_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of and not element_cls.meta_.abstract:
         raise IncorrectUsageError(
-            {
-                "_command": [
-                    f"Command `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
-                ]
-            }
+            f"Command `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
         )
 
     return element_cls

src/protean/core/command_handler.py

@@ -28,11 +28,7 @@ def command_handler_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Command Handler `{element_cls.__name__}` needs to be associated with an Aggregate"
-                ]
-            }
+            f"Command Handler `{element_cls.__name__}` needs to be associated with an Aggregate"
         )
 
     return element_cls

src/protean/core/domain_service.py

@@ -114,11 +114,7 @@ def domain_service_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of or len(element_cls.meta_.part_of) < 2:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Domain Service `{element_cls.__name__}` needs to be associated with two or more Aggregates"
-                ]
-            }
+            f"Domain Service `{element_cls.__name__}` needs to be associated with two or more Aggregates"
         )
 
     # Iterate through methods marked as `@invariant` and record them for later use

src/protean/core/entity.py

@@ -621,11 +621,7 @@ def entity_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Entity `{element_cls.__name__}` needs to be associated with an Aggregate"
-                ]
-            }
+            f"Entity `{element_cls.__name__}` needs to be associated with an Aggregate"
         )
 
     # Set up reference fields

src/protean/core/event.py

@@ -58,11 +58,7 @@ def domain_event_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of and not element_cls.meta_.abstract:
         raise IncorrectUsageError(
-            {
-                "_event": [
-                    f"Event `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
-                ]
-            }
+            f"Event `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
         )
 
     return element_cls

src/protean/core/event_handler.py

@@ -36,11 +36,7 @@ def event_handler_factory(element_cls, domain, **opts):
 
     if not (element_cls.meta_.part_of or element_cls.meta_.stream_category):
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Event Handler `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
-                ]
-            }
+            f"Event Handler `{element_cls.__name__}` needs to be associated with an aggregate or a stream"
         )
 
     return element_cls

src/protean/core/event_sourced_repository.py

@@ -33,9 +33,7 @@ def __init__(self, domain) -> None:
 
     def add(self, aggregate: BaseAggregate) -> None:
         if aggregate is None:
-            raise IncorrectUsageError(
-                {"_entity": ["Aggregate object to persist is invalid"]}
-            )
+            raise IncorrectUsageError("Aggregate object to persist is invalid")
 
         # Proceed only if aggregate has events
         if len(aggregate._events) > 0:
@@ -105,20 +103,12 @@ def event_sourced_repository_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Repository `{element_cls.__name__}` should be associated with an Aggregate"
-                ]
-            }
+            f"Repository `{element_cls.__name__}` should be associated with an Aggregate"
         )
 
     if not element_cls.meta_.part_of.meta_.is_event_sourced:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Repository `{element_cls.__name__}` can only be associated with an Event Sourced Aggregate"
-                ]
-            }
+            f"Repository `{element_cls.__name__}` can only be associated with an Event Sourced Aggregate"
         )
 
     return element_cls

src/protean/core/model.py

@@ -41,11 +41,7 @@ def model_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Model `{element_cls.__name__}` should be associated with an Entity or Aggregate"
-                ]
-            }
+            f"Model `{element_cls.__name__}` should be associated with an Entity or Aggregate"
         )
 
     return element_cls

src/protean/core/repository.py

@@ -266,11 +266,7 @@ def repository_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.part_of:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Repository `{element_cls.__name__}` should be associated with an Aggregate"
-                ]
-            }
+            f"Repository `{element_cls.__name__}` should be associated with an Aggregate"
         )
 
     # FIXME Uncomment
@@ -284,11 +280,7 @@ def repository_factory(element_cls, domain, **opts):
         database.value for database in Database
     ]:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Repository `{element_cls.__name__}` should be associated with a valid Database"
-                ]
-            }
+            f"Repository `{element_cls.__name__}` should be associated with a valid Database"
         )
 
     return element_cls

src/protean/core/subscriber.py

@@ -39,20 +39,12 @@ def subscriber_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.event:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Subscriber `{element_cls.__name__}` needs to be associated with an Event"
-                ]
-            }
+            f"Subscriber `{element_cls.__name__}` needs to be associated with an Event"
         )
 
     if not element_cls.meta_.broker:
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"Subscriber `{element_cls.__name__}` needs to be associated with a Broker"
-                ]
-            }
+            f"Subscriber `{element_cls.__name__}` needs to be associated with a Broker"
         )
 
     return element_cls

src/protean/core/value_object.py

@@ -44,36 +44,24 @@ def __validate_for_basic_field_types(subclass):
             # Value objects can hold all kinds of fields, except associations
             if isinstance(field_obj, (Reference, Association)):
                 raise IncorrectUsageError(
-                    {
-                        "_value_object": [
-                            f"Value Objects cannot have associations. "
-                            f"Remove {field_name} ({field_obj.__class__.__name__}) from class {subclass.__name__}"
-                        ]
-                    }
+                    f"Value Objects cannot have associations. "
+                    f"Remove {field_name} ({field_obj.__class__.__name__}) from class {subclass.__name__}"
                 )
 
     @classmethod
     def __validate_for_non_identifier_fields(subclass):
         for field_name, field_obj in fields(subclass).items():
             if field_obj.identifier:
                 raise IncorrectUsageError(
-                    {
-                        "_value_object": [
-                            f"Value Objects cannot contain fields marked 'identifier' (field '{field_name}')"
-                        ]
-                    }
+                    f"Value Objects cannot contain fields marked 'identifier' (field '{field_name}')"
                 )
 
     @classmethod
     def __validate_for_non_unique_fields(subclass):
         for field_name, field_obj in fields(subclass).items():
             if field_obj.unique:
                 raise IncorrectUsageError(
-                    {
-                        "_value_object": [
-                            f"Value Objects cannot contain fields marked 'unique' (field '{field_name}')"
-                        ]
-                    }
+                    f"Value Objects cannot contain fields marked 'unique' (field '{field_name}')"
                 )
 
     def __init__(self, *template, **kwargs):  # noqa: C901
@@ -176,11 +164,7 @@ def __setattr__(self, name, value):
             return super().__setattr__(name, value)
         else:
             raise IncorrectUsageError(
-                {
-                    "_value_object": [
-                        "Value Objects are immutable and cannot be modified once created"
-                    ]
-                }
+                "Value Objects are immutable and cannot be modified once created"
             )
 
     def _postcheck(self, return_errors=False):

src/protean/core/view.py

@@ -65,12 +65,8 @@ def __validate_for_basic_field_types(subclass):
         for field_name, field_obj in declared_fields(subclass).items():
             if isinstance(field_obj, (Reference, Association, ValueObject)):
                 raise IncorrectUsageError(
-                    {
-                        "_entity": [
-                            f"Views can only contain basic field types. "
-                            f"Remove {field_name} ({field_obj.__class__.__name__}) from class {subclass.__name__}"
-                        ]
-                    }
+                    f"Views can only contain basic field types. "
+                    f"Remove {field_name} ({field_obj.__class__.__name__}) from class {subclass.__name__}"
                 )
 
     def __init__(self, *template, **kwargs):
@@ -110,11 +106,7 @@ def view_factory(element_cls, domain, **opts):
 
     if not element_cls.meta_.abstract and not hasattr(element_cls, _ID_FIELD_NAME):
         raise IncorrectUsageError(
-            {
-                "_entity": [
-                    f"View `{element_cls.__name__}` needs to have at least one identifier"
-                ]
-            }
+            f"View `{element_cls.__name__}` needs to have at least one identifier"
         )
 
     element_cls.meta_.provider = (