python marshmallow使用示例

"""
棉花糖，序列化工具

核心方法：
序列化：schema.dump(object)、schema.dumps(object)
反序列化：schema.load(dict)

"""
import uuid
from datetime import datetime
from pprint import pprint

from marshmallow import Schema, fields, post_load, ValidationError, validate

"""
    序列化和反序列化
"""

print("                                                   v v v")
print("创建自定义对象----------------------------------------v v")
print("                                                     v")


# 创建自定义对象object
class User:
    def __init__(self, name, email, created_at):
        self.name = name
        self.email = email
        self.created_at = created_at


print("                                                   v v v")
print("创建Schema的两种方式----------------------------------v v")
print("                                                     v")


# 创建结构描述
# 方式一
class UserSchema(Schema):
    name = fields.Str()
    email = fields.Email()
    created_at = fields.DateTime()

    @post_load
    def make_user(self, data, **kwargs):
        return User(**data)


# 方式二
UserSchema2 = Schema.from_dict({"name": fields.Str(), "email": fields.Email(), "created_at": fields.DateTime()})

print("                                                   v v v")
print("序列化对象示例----------------------------------------v v")
print("                                                     v")

# 序列化对象
user = User("zht", "2862058843@163.com", datetime.now())
userSchema = UserSchema()
result = userSchema.dump(user)
# 美化输出
pprint(result)
print(type(result))
userSchema2 = UserSchema2()
result2 = userSchema2.dump(user)
pprint(result2)
# print(result)

# 转成json字符串
json_result = userSchema2.dumps(user)
pprint(json_result)
print(type(json_result))

print("                                                   v v v")
print("序列化对象示例(过滤输出)-------------------------------v v")
print("                                                     v")

# 过滤输出
userSchema2 = UserSchema2(only=('name', 'email'))
json_result = userSchema2.dump(user)
pprint(json_result)
print(type(json_result))
print(json_result['name'])

print("                                                   v v v")
print("返序列化对象示例--------------------------------------v v")
print("                                                     v")

# 反序列化对象 注意的是 字典里的key，对象构造函数一定要有此key
user_data = {
    "created_at": "2014-08-11T05:26:03.869245",
    "email": "ken@yahoo.com",
    "name": "Ken",
}
userSchema3 = UserSchema()
result = userSchema3.load(user_data)
pprint(result)
print(type(result))

# 反序列化对象集合
user1 = User("zht1", "2862058843@163.com", datetime.now())
user2 = User("zht2", "2862058843@164.com", datetime.now())
user3 = User("zht3", "2862058843@165.com", datetime.now())

users = [user1, user2, user3]
userSchemas = UserSchema(many=True)
result = userSchemas.dump(users)
pprint(result)

"""
验证属性值
"""

print("                                                   v v v")
print("验证属性值示例----------------------------------------v v")
print("                                                     v")

# 验证一个对象
print("验证一个对象")
try:
    result = UserSchema().load({"name": "zht", "email": "zht"})
    print(result)
except ValidationError as e:
    print(e.messages)
    print(e.valid_data)

# 验证多个对象
print("验证多个对象")


class BandMemberSchema(Schema):
    name = fields.String(required=True)
    email = fields.Email()


user_data = [
    {"email": "mick@stones.com", "name": "Mick"},
    {"email": "invalid", "name": "Invalid"},  # invalid email
    {"email": "keith@stones.com", "name": "Keith"},
    {"email": "charlie@stones.com"},  # missing "name"
]

try:
    BandMemberSchema(many=True).load(user_data)
    print(result)
except ValidationError as e:
    print(e.messages)
    print(e.valid_data)

# 通过传递 validate参数传递验证器对字段进行验证
print("通过传递 validate参数传递验证器对字段进行验证")


class MemberSchema(Schema):
    name = fields.Str(validate=validate.Length(min=1))  # 最小字符长度
    permission = fields.Str(validate=validate.OneOf(["read", "write", "admin"]))  # 必须是其中一个
    age = fields.Int(validate=validate.Range(min=18, max=40))  # 年龄必须是18到40


in_data = {"name": "1", "permission": "invalid", "age": 71}

try:
    MemberSchema().load(in_data)
except ValidationError as e:
    print(e.messages)  # 输出针对每个字段的错误信息
    print(e.valid_data)  # 输出有效的字段 （验证通过的字段）


# 自己实现一个验证器

def validate_quantity(n):
    if n < 0:
        raise ValidationError("Quantity must be greater than 0.")
    if n > 30:
        raise ValidationError("Quantity must not be greater than 30.")


class ItemSchema(Schema):
    quantity = fields.Integer(validate=validate_quantity)


in_data = {"quantity": -1}

try:
    result = ItemSchema().load(in_data)
    print(result)
except ValidationError as e:
    print(e.messages)  # 输出针对每个字段的错误信息
    print(e.valid_data)  # 输出有效的字段 （验证通过的字段）

# 自定义错误信息

print("自定义字段验证required的错误消息")


class TRequiredSchema(Schema):
    name = fields.String(required=True)
    age = fields.Integer(required=True, error_messages={"required": "Age is required."})
    city = fields.String(
        required=True,
        error_messages={"required": {"message": "City required", "code": 400}},
    )
    email = fields.Email()


try:
    result = TRequiredSchema().load({"email": "foo@bar.com"})
except ValidationError as err:
    pprint(err.messages)
    # {'age': ['Age is required.'],
    # 'city': {'code': 400, 'message': 'City required'},
    # 'name': ['Missing data for required field.']}

print("指定默认值")


# 指定默认
class DefaultSchema(Schema):
    id = fields.UUID(missing=uuid.uuid1)
    birthdate = fields.DateTime(default=datetime(2017, 9, 29))
    name = fields.String(default="火")


print(DefaultSchema().load({}))
# {'id': UUID('337d946c-32cd-11e8-b475-0022192ed31b')}
print(DefaultSchema().dump({}))
# {'birthdate': '2017-09-29T00:00:00+00:00'}