def to_dict(self):
        """ Transform an attribute to a dict
        """
        data = {}

        # mandatory characteristics
        data["name"] = self.name
        data["description"] = self.description if self.description and len(self.description) else None
        data["type"] = self.type if self.type and len(self.type) else None
        data["allowed_chars"] = self.allowed_chars if self.allowed_chars and len(self.allowed_chars) else None
        data["allowed_choices"] = self.allowed_choices
        data["autogenerated"] = self.autogenerated
        data["channel"] = self.channel if self.channel and len(self.channel) else None
        data["creation_only"] = self.creation_only
        data["default_order"] = self.default_order
        data["default_value"] = self.default_value if self.default_value and len(self.default_value) else None
        data["deprecated"] = self.deprecated
        data["exposed"] = self.exposed
        data["filterable"] = self.filterable
        data["format"] = self.format if self.format and len(self.format) else None
        data["max_length"] = int(self.max_length) if self.max_length is not None else None
        data["max_value"] = int(self.max_value) if self.max_value is not None else None
        data["min_length"] = int(self.min_length) if self.min_length is not None else None
        data["min_value"] = int(self.min_value) if self.min_value is not None else None
        data["orderable"] = self.orderable
        data["read_only"] = self.read_only
        data["required"] = self.required
        data["transient"] = self.transient
        data["unique"] = self.unique
        data["uniqueScope"] = self.unique_scope if self.unique_scope and len(self.unique_scope) else None
        data["subtype"] = self.subtype if self.subtype and len(self.subtype) else None
        data["userlabel"] = self.userlabel if self.userlabel and len(self.userlabel) else None

        return data
Transform an attribute to a dict