1. 结构数据验证

我们的程序往往需要从外部获取数据,比如服务请求都是外部输入数据,比如程序启动可以导入外部设定的配置.通常我们使用json(或者yaml)或者是python中的字典作为外部数据的标准格式.结构数据验证无非是验证字段是否存在,字段值是否符合要求.一个比较通用的数据描述协议是jsonschema其python实现是包jsonschema.

一个比较好的语法描述是Json Schema 快速入门,更加详细的可以看understanding-json-schema

1.1. 例子:

我们来验证如下的json格式描述的用户

{     "name": "Emily",     "age": 123,     "email":"[email protected]"     "gender": "female",     "like_film":["a","b"] } 

定义结构

schema = {     "$schema": "http://json-schema.org/draft-07/schema#",     "$id": "http://yourdomain.com/schemas/user-schema.json",     "title": "User",     "description": "用户",     "type" : "object",     "properties" : {         "name" : {             "description": "user name",             "type" : "string"         },"age" : {             "description": "user age",             "type" : "integer",             "minimum": 0,             "maximum":140,             "exclusiveMaximum": True         },"gender":{             "description": "user gender",             "type": "string",              "enum": ["male", "female"]         },"email":{             "description": "user email",             "type" : "string",             "pattern":r"^(\w)+(\.\w+)*@(\w)+((\.\w+)+)$"         },"like_film":{             "description": "user like file's name",             "type": "array",             "items": {                 "type": "string"             },         }     },     "required": [ "name", "age", "gender" ] } 

验证字典是否满足结构

from jsonschema import validate 

validate(instance={     "name": "Emily",     "age": 123,     "gender": "female",     "like_film":["a","b"] }, schema=schema) 

validate(instance={     "name": "Emily",     "age": 123,     "gender": "female",     "email":"[email protected]" }, schema=schema) 

validate(instance={     "name": "Emily",     "age": 123,     "gender": "female",     "email":"[email protected]" }, schema=schema) 

validate( instance={"name" : "Eggs", "price" : "Invalid"}, schema=schema, ) 

---------------------------------------------------------------------------  ValidationError                           Traceback (most recent call last)  <ipython-input-6-075aa0c4612f> in <module>       1 validate( ----> 2 instance={"name" : "Eggs", "price" : "Invalid"}, schema=schema,       3 )        ~/Lib/conda/anaconda3/lib/python3.7/site-packages/jsonschema/validators.py in validate(instance, schema, cls, *args, **kwargs)     539         cls = validator_for(schema)     540     cls.check_schema(schema) --> 541     cls(schema, *args, **kwargs).validate(instance)   ~/Lib/conda/anaconda3/lib/python3.7/site-packages/jsonschema/validators.py in validate(self, *args, **kwargs)     128         def validate(self, *args, **kwargs):     129             for error in self.iter_errors(*args, **kwargs): --> 130                 raise error     131      132         def is_type(self, instance, type):   ValidationError: 'age' is a required property  Failed validating 'required' in schema:     {'description': '用户',      'properties': {'age': {'description': 'user age',                             'exclusiveMaximum': True,                             'maximum': 140,                             'minimum': 0,                             'type': 'integer'},                     'email': {'description': 'user email',                               'pattern': '^(\\w)+(\\.\\w+)*@(\\w)+((\\.\\w+)+)$',                               'type': 'string'},                     'gender': {'description': 'user gender',                                'enum': ['male', 'female'],                                'type': 'string'},                     'like_film': {'description': "user like file's name",                                   'items': {'type': 'string'},                                   'type': 'array'},                     'name': {'description': 'user name', 'type': 'string'}},      'required': ['name', 'age', 'gender'],      'title': 'User',      'type': 'object'}  On instance:     {'name': 'Eggs', 'price': 'Invalid'} 

jsonschema最大的优点是跨语言,使用同一套描述规范可以在c,cpp,go,js,python之间进行传递,这个类似protobuf,可以做到代码即文件,同时它支持继承,可以维护一个统一的服务用语描述schema,同时支持使用$id描述自身的维护地址,使用$ref来引用外部或者别处定义的对象.