def get_field_definition_by_name(self, field_name):
try:<EOL><INDENT>return self._fields_by_name[self.resolve_field_name(field_name)]<EOL><DEDENT>except KeyError:<EOL><INDENT>raise UnknownField(self, field_name, self._fields_by_name.keys())<EOL><DEDENT>
Get JSON field definition for field matching provided name or key

        .. versionchanged:: 4.1.0
            Added support for field keys

        Args:
            field_name (str): Target field name or key to get definition for

        Raises:
            swimlane.exceptions.UnknownField: Raised when given a field name not found in App

        Returns:
            dict: Field metadata definition