param_validator 核心代码实现

news2025/5/24 16:06:20

一、前置说明

1、总体目录

《 pyparamvalidate 参数校验器，从编码到发布全过程》

2、相关回顾

pyparamvalidate 项目背景和需求分析

3、本节目标

param_validator 核心代码实现

二、操作步骤

1、项目目录

atme : @me 用于存放临时的代码片断或其它内容。
pyparamvalidate : 新建一个与项目名称同名的package，为了方便发布至 pypi 。
core : 用于存放核心代码。
tests : 用于存放测试代码。
utils : 用于存放一些工具类或方法。

2、代码实现

pyparamvalidate/core/param_validator.py

import functools
import inspect
import os.path


class ParameterValidationError(Exception):

    def __init__(self, func, parameter_name, parameter_value, param_rule_description=None, exception_msg=None):
        self.func_name = func.__name__
        self.parameter_name = parameter_name
        self.parameter_value = parameter_value
        self.param_rule_description = param_rule_description
        self.exception_msg = exception_msg

        super().__init__(self.error_message())

    def error_message(self):
        return (
            f"Parameter '{self.parameter_name}' in function '{self.func_name}' is invalid. "
            f"\t{'Error: ' + self.exception_msg if self.exception_msg else ''}"
            f"\t{'Please refer to: ' + self.param_rule_description if self.param_rule_description else ''}"
        )


class ParameterValidator:
    def __init__(self, param_name, param_rule_des=None):
        """
        :param param_name: 参数名
        :param param_rule_des: 该参数的规则描述
        """
        self.param_name = param_name
        self.param_rule_description = param_rule_des

        # 用于收集校验器
        self.validators = []

    def __call__(self, func):

        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            # 获取函数的参数和参数值
            bound_args = inspect.signature(func).bind(*args, **kwargs).arguments

            # 如果函数被装饰，且以关键字参数传值，则从 kwargs 中取参数值
            if self.param_name in kwargs:
                value = kwargs[self.param_name]

            # # 如果函数被装饰，且以位置参数传值，则从 bound_args 中取参数值
            elif self.param_name in bound_args:
                value = bound_args.get(self.param_name)

            # 如果函数没有被装饰，则直接执行返回结果
            else:
                return func(*args, **kwargs)

            # 使用验证器进行验证
            for validator, exception_msg in self.validators:

                # 如果没验证通过，则抛出异常
                if not validator(value):
                    raise ParameterValidationError(func, self.param_name, value,
                                                   self.param_rule_description, exception_msg)
            # 所有参数校验通过，则执行函数返回结果
            return func(*args, **kwargs)

        return wrapper

    def add_validator(self, validator_function, exception_msg=None):
        self.validators.append((validator_function, exception_msg))
        return self

    def is_string(self, exception_msg=None):
        return self.add_validator(lambda value: isinstance(value, str), exception_msg)

3、测试代码

pyparamvalidate/tests/test_param_validator.py

import os

import pytest

from pyparamvalidate.core.param_validator import ParameterValidator, ParameterValidationError


def test_is_string_validator_passing_01():
    """
    不描述参数规则
    """

    @ParameterValidator("param").is_string()
    def example_function(param):
        print(param)
        return param

    assert example_function(param="test") == "test"

    with pytest.raises(ParameterValidationError) as exc_info:
        example_function(param=123)

    print(exc_info.value)
    assert "invalid" in str(exc_info.value)


def test_is_string_validator_passing_02():
    """
    在校验器中描述参数规则
    """

    @ParameterValidator("param").is_string("Value must be a string")
    def example_function(param):
        print(param)
        return param

    assert example_function(param="test") == "test"

    with pytest.raises(ParameterValidationError) as exc_info:
        example_function(param=123)

    print(exc_info.value)
    assert "Value must be a string" in str(exc_info.value)


def test_is_string_validator_passing_03():
    """
    在 ParameterValidator 实例化时描述参数规则
    """

    @ParameterValidator("param", param_rule_des="Value must be a string").is_string()
    def example_function(param):
        print(param)
        return param

    assert example_function(param="test") == "test"

    with pytest.raises(ParameterValidationError) as exc_info:
        example_function(param=123)

    print(exc_info.value)
    assert "Value must be a string" in str(exc_info.value)

4、日志输出

执行 test 的日志如下，验证通过：

============================= test session starts =============================
collecting ... collected 3 items

test_param_validator.py::test_is_string_validator_passing_01 PASSED      [ 33%]test
Parameter 'param' in function 'example_function' is invalid. 		

test_param_validator.py::test_is_string_validator_passing_02 PASSED      [ 66%]test
Parameter 'param' in function 'example_function' is invalid. 	Error: Value must be a string	

test_param_validator.py::test_is_string_validator_passing_03 PASSED      [100%]test
Parameter 'param' in function 'example_function' is invalid. 		Please refer to: Value must be a string


============================== 3 passed in 0.01s ==============================