Fix field name validation

CHANGELOG.rst

@@ -1,3 +1,11 @@
+Version 11.1.0
+--------------
+
+**Added**:
+
+- Added custom field name validation.
+
+
 Version 11.0.0
 --------------
 

docs/schema.rst

@@ -304,6 +304,13 @@ create a field handler. Let's call it ``my_field``.
 Afterwards, you need to register this field handler using a name you intend to use later. In this example,
 we will name the field ``hohoho``.
 
+.. note::
+
+    To avoid receiving a ValueError, the field name must be a string that conforms to a valid Python identifier.
+
+    Also, it's important to note that **every** field handler must be registered using a unique name,
+    otherwise, you will override an existing field handler. The filed names are case-sensitive.
+
 .. code:: python
 
     >>> from mimesis.schema import Field
@@ -313,7 +320,8 @@ we will name the field ``hohoho``.
     >>> # Now you can use it:
     >>> field("hohoho", a="a", b="b")
     'a'
-    >>> # Note that you can still use the key function:
+    >>> # Note that you can still use the key function, but the order of arguments matters, so
+    >>> # key goes first, and then the rest of the arguments which are passed to the field handler.
     >>> field("hohoho", key=str.upper, a="a", b="b")
     'A'
 
@@ -331,12 +339,6 @@ You can register multiple fields at once:
     >>> field("mf2", key=str.upper)
 
 
-.. note::
-
-    It's important to note that **every** field handler must be registered using a unique name,
-    otherwise it will override the existing field handler with the same name.
-
-
 Unregister Field Handler
 ~~~~~~~~~~~~~~~~~~~~~~~~
 

mimesis/__init__.py

@@ -138,7 +138,7 @@
     "__license__",
 ]
 
-__version__ = "11.0.0"
+__version__ = "11.1.0"
 __title__ = "mimesis"
 __description__ = "Mimesis: Fake Data Generator."
 __url__ = "https://github.com/lk-geimfari/mimesis"

mimesis/schema.py

@@ -186,18 +186,19 @@ def perform(
 
         return result
 
-    def __str__(self) -> str:
-        return f"{self.__class__.__name__} <{self._gen.locale}>"
-
     def register_field(self, field_name: str, field_handler: FieldHandler) -> None:
         """Register a new field handler.
 
         :param field_name: Name of the field.
         :param field_handler: Callable object.
         """
+
         if not isinstance(field_name, str):
             raise TypeError("Field name must be a string.")
 
+        if not field_name.isidentifier():
+            raise ValueError("Field name must be a valid Python identifier.")
+
         if not callable(field_handler):
             raise TypeError("Handler must be a callable object.")
 
@@ -243,6 +244,9 @@ def unregister_all_fields(self) -> None:
         """
         self._custom_fields.clear()
 
+    def __str__(self) -> str:
+        return f"{self.__class__.__name__} <{self._gen.locale}>"
+
 
 class Field(BaseField):
     """Greedy field.

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "mimesis"
-version = "11.0.0"
+version = "11.1.0"
 description = "Mimesis: Fake Data Generator."
 authors = ["Isaak Uchakaev <[email protected]>"]
 license = "MIT"