Marshmallow¶
官方文档:https://marshmallow.readthedocs.io/en/latest/
Marshmallow,中文译作:棉花糖。是一个轻量级的数据格式转换的模块,也叫序列化和反序列化模块,常用于将复杂的orm模型对象与python原生数据类型之间相互转换。marshmallow提供了丰富的api功能。如下:
Serializing
序列化[可以把数据对象转化为可存储或可传输的数据类型,例如:objects/object->list/dict,dict/list->string]
Deserializing
反序列化器[把可存储或可传输的数据类型转换成数据对象,例如:list/dict->objects/object,string->dict/list]
Validation
数据校验,可以在反序列化阶段,针对要转换数据的内容进行类型验证或自定义验证。
Marshmallow本身是一个单独的库,基于我们当前项目使用框架是flask并且数据库ORM框架使用SQLAlchemy,所以我们可以通过安装flask-sqlalchemy和marshmallow-sqlalchemy集成到项目就可以了。
基本安装和配置¶
模块安装:
pip install -U marshmallow-sqlalchemy
pip install -U flask-sqlalchemy
pip install -U flask-marshmallow
Marshmallow模块快速使用,我们单独创建一个python文件进行基本的使用,docs/main.py:
from datetime import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
app = Flask(__name__)
app.config["DEBUG"] = True
app.config["SQLALCHEMY_DATABASE_URI"]="mysql://root:123@127.0.0.1:3306/mofang?charset=utf8mb4"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db = SQLAlchemy()
db.init_app(app)
ma = Marshmallow()
ma.init_app(app)
class User(db.Model):
__tablename__ = "tb_user"
id = db.Column(db.Integer, primary_key=True, comment="主键ID")
username = db.Column(db.String(255), index=True, comment="用户名")
password = db.Column(db.String(255), comment="登录密码")
mobile = db.Column(db.String(15), index=True, comment="手机号码")
sex = db.Column(db.Boolean, default=True, comment="性别")
email = db.Column(db.String(255), index=True, comment="邮箱")
created_time = db.Column(db.DateTime, default=datetime.now, comment="创建时间")
updated_time = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now, comment="更新时间")
def __repr__(self):
return "<%s: %s>" % (self.__class__.name,self.username)
@app.route("/")
def index():
return "ok"
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run(debug=True,port=5555)
基本构造器(Schema)¶
也可以叫基本模式类或基本序列化器类。
marshmallow转换数据格式主要通过构造器类(序列化器)来完成。在marshmallow使用过程中所有的构造器类必须直接或间接继承于Schema基类,而Schema基类提供了数据转换的基本功能:序列化,验证数据和反序列化。
基于Schema完成数据序列化转换¶
from datetime import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
app = Flask(__name__)
app.config["DEBUG"] = True
app.config["SQLALCHEMY_DATABASE_URI"]="mysql://root:123@127.0.0.1:3306/yingming?charset=utf8mb4"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
app.config["SQLALCHEMY_ECHO"] = True
db = SQLAlchemy()
db.init_app(app)
ma = Marshmallow()
ma.init_app(app)
"""模型"""
class User(db.Model):
__tablename__ = "desc_user"
id = db.Column(db.Integer, primary_key=True, comment="主键ID")
username = db.Column(db.String(255), index=True, comment="用户名")
password = db.Column(db.String(255), comment="登录密码")
mobile = db.Column(db.String(15), index=True, comment="手机号码")
sex = db.Column(db.Boolean, default=True, comment="性别")
email = db.Column(db.String(255), index=True, comment="邮箱")
created_time = db.Column(db.DateTime, default=datetime.now, comment="创建时间")
updated_time = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now, comment="更新时间")
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.username)
"""序列化器"""
from marshmallow import Schema, fields
class UserSchema(Schema):
username = fields.String()
mobile = fields.String()
sex = fields.Boolean()
email = fields.Email()
created_time = fields.DateTime()
updated_time = fields.DateTime()
@app.route("/1")
def index1():
"""序列化一个对象成字典或字符串"""
# 模拟从数据库中读取出来的模型类
user = User(
username="xiaoming",
mobile="13312345677",
sex=True,
email="133123456@qq.com",
created_time=datetime.now(),
updated_time=datetime.now()
)
db.session.add(user)
db.session.commit()
print(user)
# 序列化成一个字典
us = UserSchema()
result = us.dump(user)
print(result, type(result))
# 序列化器成一个字符串[符合json语法]
result = us.dumps(user)
print(result, type(result))
# 如果要序列化多个模型对象,可以使用many=True
result = us.dump([user,user,user], many=True)
print(result)
result = us.dumps([user,user,user], many=True)
print(result)
return "ok"
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run(debug=True, port=5555)
schema常用属性数据类型
| 类型 | 描述 |
|---|---|
fields.Dict(keys, type]] = None, values, …) |
字典类型,常用于接收json类型数据 |
fields.List(cls_or_instance, type], **kwargs) |
列表类型,常用于接收数组数据 |
fields.Tuple(tuple_fields, args, *kwargs) |
元组类型 |
fields.String(*, default, missing, data_key, …) |
字符串类型 |
fields.UUID(*, default, missing, data_key, …) |
UUID格式类型的字符串 |
fields.Number(, as_string, *kwargs) |
数值基本类型 |
fields.Integer(, strict, *kwargs) |
整型 |
fields.Decimal(places, rounding, *, allow_nan, …) |
数值型 |
fields.Boolean(, truthy, falsy, *kwargs) |
布尔型 |
fields.Float(, allow_nan, as_string, *kwargs) |
浮点数类型 |
fields.DateTime(format, **kwargs) |
日期时间类型 |
fields.Time(format, **kwargs) |
时间类型 |
fields.Date(format, **kwargs) |
日期类型 |
fields.Url(*, relative, schemes, Set[str]]] = None, …) |
url网址字符串类型,自带url地址的校验规则 |
fields.Email(args, *kwargs) |
邮箱字符串类型,自带email地址的校验规则 |
fields.IP(*args[, exploded]) |
IP地址字符串类型 |
fields.IPv4(*args[, exploded]) |
IPv4地址字符串类型 |
fields.IPv6(*args[, exploded]) |
IPv6地址字符串类型 |
fields.Method(serialize, deserialize, **kwargs) |
基于Schema类方法返回值的字段 |
fields.Function(serialize, Any], Callable[[Any, …) |
基于函数返回值得字段 |
fields.Nested(nested, type, str, Callable[[], …) |
嵌套类型或外键类型 |
Schema数据类型的常用通用属性
| 属性名 | 描述 |
|---|---|
| default | 序列化阶段中设置字段的默认值 |
| missing | 反序列化阶段中设置字段的默认值 |
| validate | 反序列化阶段调用的内置数据验证器或者内置验证集合 |
| required | 反序列化阶段调用的,设置当前字段的必填字段 |
| allow_none | 反序列化阶段调用的,是否允许为空 |
| load_only | 是否在反序列化阶段才使用到当前字段,相当于drf框架的write_only |
| dump_omly | 是否在序列化阶段才使用到当前字段,相当于drf框架的read_only |
| error_messages | 使用校验值validate选项以后设置的错误提示,字典类型,可以用来替代默认的字段异常提示语,格式: error_messages={“required”: “用户名为必填项。”} |
构造器嵌套使用¶
from datetime import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
app = Flask(__name__)
app.config["DEBUG"] = True
app.config["SQLALCHEMY_DATABASE_URI"]="mysql://root:123@127.0.0.1:3306/yingming?charset=utf8mb4"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
app.config["SQLALCHEMY_ECHO"] = True
db = SQLAlchemy()
db.init_app(app)
ma = Marshmallow()
ma.init_app(app)
"""模仿ORM的模型"""
class Model(object):
pass
class User(Model):
def __init__(self, name, email):
self.name = name
self.email = email
self.created_at = datetime.now()
self.books = [] # 用来代替MySQL中的外检关系,实现1对多或多对多
self.friends = [] # 用来代替MySQL中的外检关系,实现自关联
class Book(Model):
def __init__(self, title, author):
self.title = title
self.author = author # 用来代替MySQL中的外键关系,1对1
"""序列化器"""
from marshmallow import Schema, fields
class UserSchema(Schema):
"""用户的序列化器"""
name = fields.String()
email = fields.Email()
"""1对多,多对多"""
# 在fields.Nested外围包裹一个List列表字段,则可以返回多个结果了。exclude表示排除
# books = fields.List(fields.Nested(lambda: BookSchema(exclude=["author"])))
# 简写方式:
books = fields.Nested(lambda : BookSchema(many=True, exclude=["author"]))
"""自关联"""
# 自关联就是一个模型中既存在主键关系,也存在外键关系的情况
# 方式1:使用自身"self"作为外键的方式,并可以指定序列化模型的多个字段
# friends = fields.Nested(lambda: "self", only=("name", "email", "books"), many=True)
# 方式2:使用Pluck字段可以用单个值来替换嵌套的数据,只可以得到模型的单个字段值
friends = fields.Pluck(lambda: "self", "name", many=True)
class BookSchema(Schema):
"""图书的序列化器"""
title = fields.String()
author = fields.Nested(lambda: UserSchema(exclude=["books"]))
@app.route("/1")
def index1():
"""构造器嵌套使用"""
# 假设根据当前作者,查找对应的作者发布的图书列表
user0 = User(name="南派三叔", email="sanshu@163.com")
book1 = Book(title="盗墓笔记1", author=user0)
book2 = Book(title="盗墓笔记2", author=user0)
book3 = Book(title="盗墓笔记3", author=user0)
user0.books = [book1, book2, book3]
us = UserSchema()
result = us.dump(user0)
print(result)
bs = BookSchema()
result = bs.dump([book1, book2, book3], many=True)
print(result)
return "ok"
@app.route("/2")
def index2():
"""自关联"""
user0 = User(name="南派三叔", email="sanshu@163.com")
user1 = User(name="刘慈欣", email="sanshu@163.com")
user2 = User(name="天下霸唱", email="sanshu@163.com")
user0.friends = [user1, user2]
us = UserSchema()
result = us.dump(user0)
print(result)
return "ok"
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run(debug=True, port=5555)
基于Schema完成数据反序列化转换¶
代码:
from marshmallow import Schema, fields, validate, ValidationError
class UserSchema(Schema):
# required=True 必填字段,否则可以不填写
name = fields.Str(required=True, validate=validate.Length(min=3,max=16, error="用户名有误!name必须在{min}~{max}个字符长度之间"))
email = fields.Email(error_messages={"invalid": "无效的邮箱地址!"})
age = fields.Int(validate=validate.Range(min=18, max=40, error="{input}有误!age的数值范围是{min}~{max}"))
permission = fields.Str(validate=validate.OneOf(["read", "write", "admin"], error="permisson只能是read,write和admin,三者之一"))
if __name__ == '__main__':
# 模拟客户端提交过来的数据
user_data = {"name": "xiaoming", "email": "ronnie@stones.com", "age": 35, "permission": "write"}
data_list = [user_data, user_data, user_data]
us = UserSchema() # 校验数据
"""校验一个数据"""
# # 反序列化验证
# result = us.load(user_data)
# print(result)
"""校验多个数据"""
# # 反序列化验证
result = us.load(data_list, many=True)
print(result)
反序列化转换时忽略部分数据¶
from marshmallow import Schema, fields, validate, ValidationError
class UserSchema(Schema):
name = fields.String(required=True)
age = fields.Integer(required=True)
avatar = fields.String(required=True, error_messages={"required":"avatar必须填写!"})
if __name__ == '__main__':
# result = UserSchema().load({"name":"xiaoming", "age": 42, "avatar": "1.png"})
result = UserSchema().load({"name":"xiaoming", "age": 42}, partial=("avatar",)) # 取消字段在构造器中设置的required=True的效果
print(result) # => {'age': 42}
设置字段只在序列化或反序列化阶段才启用¶
class UserSchema(Schema):
name = fields.Str()
password = fields.Str(load_only=True) # 相当于只写字段 "write-only"
created_time = fields.DateTime(dump_only=True) # 相当于只读字段 "read-only"
MarshMallow提供的钩子方法¶
marshmallow提供了一些在反序列化或者序列化阶段时自动执行的钩子装饰器。
# 序列化之前执行的钩子方法
pre_dump([fn,pass_many]) 注册要在序列化对象之前调用的方法,它会在序列化对象之前被调用。
# 序列化之后执行的钩子方法
post_dump([fn,pass_many,pass_original]) 注册要在序列化对象后调用的方法,它会在对象序列化后被调用。
# 反序列化之前执行的钩子方法
pre_load([fn,pass_many]) 在反序列化对象之前,注册要调用的方法,它会在验证数据之前调用
# 反序列化之后执行的钩子方法
post_load([fn,pass_many,pass_original]) 注册反序列化对象后要调用的方法,它会在验证数据之后被调用。
# 校验指定字段的装饰器,相当于drf的 validate_<字段>(data)
validates(field_name)
# 校验整个构造器中所有数据的装饰器,相当于drf的 validate(data)
validates_schema([fn, pass_many, ...])
from datetime import datetime
from marshmallow import Schema, fields, validate, ValidationError, decorators
from werkzeug.security import generate_password_hash, check_password_hash
class User(object):
def __init__(self, name, password, avatar):
self.name = name
self.password = password
self.avatar = avatar
self.created_time = datetime.now()
def __str__(self):
return f"<{self.__class__.__name__} [{self.name}]>"
class UserSchema(Schema):
name = fields.Str(required=True, validate=validate.Length(min=1))
password = fields.Str(load_only=True, required=True, validate=validate.Length(min=6,max=16))
# password = fields.Str(load_only=True, required=True)
# 确认密码是不需要保存到数据库的,仅仅判断用户两次输入密码是否正确
re_password = fields.Str(required=True, validate=validate.Length(min=6,max=16))
created_time = fields.DateTime(dump_only=True)
avatar = fields.Str()
# 验证单个字段
@decorators.validates(field_name="name")
def validate_name(self, data):
if data == "柯南":
raise ValidationError(message="对不起,这名字不适合我们学校!!", field_name="name")
return data
# 验证所有字段的
@decorators.validates_schema
def validate(self, data, *args, **kwargs):
if data["re_password"] != data["password"]:
raise ValidationError(message="密码和确认密码不一致!", field_name="re_password")
# 因为确认密码时不会入库的,所以检验完成以后,就从data中剔除
data.pop("re_password")
return data
@decorators.pre_load
def pre_load(self, data, *args, **kwargs):
# 常见:上传文件的处理
data["avatar"] = "1.png"
return data
# 反序列化成功之后自动执行的钩子方法
@decorators.post_load
def save_model(self, data, *args, **kwargs):
# print("反序列化之后")
# 密码加密或者数据入库
data["password"] = generate_password_hash(data["password"])
# 模拟入库代码
user = User(**data)
# db.session.add(user)
# db.session.commit()
return user
@decorators.post_dump(pass_many=True) # pass_many 表示是否接受传递进来的many参数
def post_dump(self, data, many, **kwargs):
# many=True,则返回多个结果
print("序列化之前,data=", data)
return data
@decorators.pre_dump(pass_many=True) # pass_many 表示是否接受传递进来的many参数
def pre_dump(self, data, many, **kwargs):
# many=True,则返回多个结果
print("序列化之前,data=", data)
return data
@decorators.post_dump(pass_many=True) # pass_many 表示是否接受传递进来的many参数
def post_dump(self, data, many, **kwargs):
# many=True,则返回多个结果
data["created_time"] = data["created_time"].replace("T", " ").split(".")[0]
print("序列化之后,data=", data)
return data
if __name__ == '__main__':
# 模拟客户端提交过来的数据
data = {"name": "xiaoming", "password": "123456", "re_password": "123456"}
us = UserSchema()
ret = us.load(data)
print(ret.password) # 在这里保存数据到数据库,re_password已经被钩子方法中移除了。
# # 序列化
user = User(name="小红", password="password", avatar="1.png")
ret = us.dump(user)
print(ret)
反序列化阶段对数据进行验证¶
基于内置验证器进行数据验证¶
| 内置验证器 | 描述 |
|---|---|
validate.Email(*, error) |
邮箱验证 |
validate.Equal(comparable, *, error) |
判断值是否相等 |
validate.Length(min, max, *, equal, error) |
值长度/大小验证 |
validate.OneOf(choices, labels, *, error) |
选项验证 |
validate.Range([min, max]) |
范围验证 |
validate.Regexp(regex, bytes, Pattern][, flags]) |
正则验证 |
validate.URL(*, relative, schemes, Set[str]]] = None, …) |
验证是否为URL |
代码:
from marshmallow import Schema, fields, validate, ValidationError
class UserSchema(Schema):
name = fields.Str(validate=validate.Length(min=1))
permission = fields.Str(validate=validate.OneOf(["read", "write", "admin"]))
age = fields.Int(validate=validate.Range(min=18, max=40))
if __name__ == '__main__':
data = {"name": "", "permission": "hello", "age": 71}
try:
UserSchema().load(data)
except ValidationError as err:
pprint(err.messages)
自定义验证方法¶
class ItemSchema(Schema):
age = fields.Integer()
@validates_schema
def validate(self,data):
"""对所有数据进行验证"""
return data
@validates("age")
def validate_age(self, data):
"""对单个数据进行验证"""
if data < 10:
raise ValidationError("年龄必须大于10岁")
if data > 70:
raise ValidationError("年龄必须小于70岁")
模型构造器(ModelSchema)¶
官方提供了SQLAlchemyAutoSchema和SQLAlchemySchema这2个类提供给我们用于编写模型构造器。
官方文档:https://github.com/marshmallow-code/marshmallow-sqlalchemy
https://marshmallow-sqlalchemy.readthedocs.io/en/latest/
SQLAlchemySchema¶
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from datetime import datetime
app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"]="mysql://root:123@127.0.0.1:3306/mofang?charset=utf8mb4"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db = SQLAlchemy()
ma = Marshmallow()
db.init_app(app)
ma.init_app(app)
class User(db.Model):
__tablename__ = "tb_user"
id = db.Column(db.Integer, primary_key=True, comment="主键ID")
username = db.Column(db.String(255), index=True, comment="用户名")
password = db.Column(db.String(255), comment="登录密码")
mobile = db.Column(db.String(15), index=True, comment="手机号码")
sex = db.Column(db.Boolean, default=True, comment="性别")
email = db.Column(db.String(255), index=True, comment="邮箱")
created_time = db.Column(db.DateTime, default=datetime.now, comment="创建时间")
updated_time = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now, comment="更新时间")
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.username)
"""模型构造器"""
from marshmallow_sqlalchemy import SQLAlchemySchema, auto_field
class UserSQLAlchemySchema(SQLAlchemySchema):
"""
SQLAlchemySchema提供了一个auto_field方法可以自动从模型中提取当前对应字段声明信息到构造器中,
但是,我们需要手动声明序列化器中调用的哪些字段,每一个都要写上
"""
id = auto_field()
username = auto_field()
mobile = auto_field()
email = auto_field()
created_time = auto_field()
sex = auto_field()
class Meta:
model = User # 指定当前模型构造器绑定的模型对象
load_instance = True
@app.route("/")
def index():
"""序列化器数据"""
"""序列化一个数据"""
# usas = UserSQLAlchemySchema()
# # user = User.query.get(1)
# # ret = usas.dump(user)
# # print(ret)
"""
{'username': 'xiaoming', 'email': '123@qq.com', 'id': 1, 'sex': True, 'created_time': '2021-11-09T18:26:48', 'mobile': '13312345678'}
"""
"""序列化多个数据"""
usas = UserSQLAlchemySchema(many=True)
user = User.query.all()
ret = usas.dump(user)
print(ret)
"""
[{'email': '123@qq.com', 'created_time': '2021-11-09T18:26:48', 'username': 'xiaoming', 'id': 1, 'mobile': '13312345678', 'sex': True}, {'email': '321@qq.com', 'created_time': '2021-11-09T18:26:48', 'username': 'xiaoming', 'id': 2, 'mobile': '13312345671', 'sex': True}]
"""
return "ok"
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run(debug=True,port=8088)
SQLAlchemyAutoSchema¶
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from datetime import datetime
app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"]="mysql://root:123@127.0.0.1:3306/mofang?charset=utf8mb4"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db = SQLAlchemy()
ma = Marshmallow()
db.init_app(app)
ma.init_app(app)
class User(db.Model):
__tablename__ = "tb_user"
id = db.Column(db.Integer, primary_key=True, comment="主键ID")
username = db.Column(db.String(255), index=True, comment="用户名")
password = db.Column(db.String(255), comment="登录密码")
mobile = db.Column(db.String(15), index=True, comment="手机号码")
sex = db.Column(db.Boolean, default=True, comment="性别")
email = db.Column(db.String(255), index=True, comment="邮箱")
created_time = db.Column(db.DateTime, default=datetime.now, comment="创建时间")
updated_time = db.Column(db.DateTime, default=datetime.now, onupdate=datetime.now, comment="更新时间")
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.username)
"""模型构造器"""
from marshmallow_sqlalchemy import SQLAlchemySchema, auto_field, SQLAlchemyAutoSchema
from marshmallow import validate
class UserSQLAlchemySchema(SQLAlchemyAutoSchema):
"""
SQLAlchemyAutoSchema提供了一个fields和exclude属性可以设置从模型类导入指定的字段声明,
其中,fields设置包含的字段,而exclude设置的排除字段,所以2个属性不能同时使用,互斥的。
另外,如果针对模型导入的字段声明,我们需要增加对字段的验证、约束,则还是可以手动声明使用auto_fields来进行
"""
username = auto_field(validate=validate.Length(min=1,max=15))
class Meta:
model = User # 指定当前模型构造器绑定的模型对象
load_instance = True
include_relationships = True # 输出模型对象时同时对外键,是否也一并进行处理,True表示一并进行序列化器,用于针对序列化器嵌套调用的情况
include_fk = True # 序列化阶段是否也一并返回主键
sql_session = db.session # 数据库连接会话对象,针对在钩子装饰器中如果希望调用db数据库回话对象,可以在此处声明完成以后,使用时通过sql_session直接调用
fields = ["id", "username", "mobile", "email", "created_time", "sex"]
# exclude = ["id", "name"] # 排除字段列表
@app.route("/")
def index():
"""序列化器数据"""
# """序列化一个数据"""
# usas = UserSQLAlchemySchema()
# user = User.query.get(1)
# ret = usas.dump(user)
# print(ret)
# """
# {'username': 'xiaoming', 'email': '123@qq.com', 'id': 1, 'sex': True, 'created_time': '2021-11-09T18:26:48', 'mobile': '13312345678'}
# """
"""序列化多个数据"""
usas = UserSQLAlchemySchema(many=True)
user = User.query.all()
ret = usas.dump(user)
print(ret)
"""
[{'email': '123@qq.com', 'created_time': '2021-11-09T18:26:48', 'username': 'xiaoming', 'id': 1, 'mobile': '13312345678', 'sex': True}, {'email': '321@qq.com', 'created_time': '2021-11-09T18:26:48', 'username': 'xiaoming', 'id': 2, 'mobile': '13312345671', 'sex': True}]
"""
return "ok"
if __name__ == '__main__':
with app.app_context():
db.create_all()
app.run(debug=True,port=8088)