嵌套结构时 Marshmallow 反序列化失败
Marshmallow deserializing fails when structure is nested
我正在尝试用棉花糖反序列化深层结构。例如:
hour = {
'day': {
'name': 'monday'
}
}
loaded_hour, error = HoursSerializationSchema().load(hour) # this works
new_practitioner_at_location = {
'hours': [
hour
]
}
loaded, error = PractitionerToServiceLocationSerializationSchema().load(new_practitioner_at_location) # this fails
当我尝试反序列化 new_practitioner_at_location
时,我得到以下信息(在序列化程序处理 'day' 键时发生):
AttributeError: 'dict' object has no attribute '_sa_instance_state'
请注意,当该结构未嵌套在 new_practitioner_at_location
内时,相同的模式用于反序列化相同的数据结构(小时)。
显示问题的独立脚本:
from sqlalchemy import Column, Integer, ForeignKey, String
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base
import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from flask_migrate import Migrate
base = declarative_base()
class HoursDay(base):
__tablename__ = 'HoursDay'
uid = Column(Integer, primary_key=True)
name = Column(String)
hour_id = Column(Integer, ForeignKey('Hours.uid'))
hour = relationship("Hours", back_populates="day")
def __init__(self, **kwargs):
super().__init__(**kwargs)
class Hours(base):
__tablename__ = 'Hours'
uid = Column(Integer, primary_key=True)
practitioner_at_location_id = Column(Integer, ForeignKey('PractitionerToServiceLocation.uid'))
practitioner_at_location = relationship('PractitionerToServiceLocation', back_populates="hours")
day = relationship(HoursDay, uselist=False, back_populates="hour")
def __repr__(self):
return f'<Hours {self.uid}>'
class PractitionerToServiceLocation(base):
"""
A practitioner practices at a number of service locations.
"""
__tablename__ = 'PractitionerToServiceLocation'
uid = Column(Integer, primary_key=True)
hours = relationship("Hours", back_populates="practitioner_at_location")
def __init__(self, **kwargs):
super().__init__(**kwargs)
def __repr__(self):
return f'<PractitionerToServiceLocation {self.uid}>'
app = Flask(__name__)
app.config.from_object(os.environ['APP_SETTINGS'])
db = SQLAlchemy(app, model_class=base)
ma = Marshmallow(app)
migrate = Migrate(app, db)
from marshmallow import fields
class HoursDaySerializationSchema(ma.ModelSchema):
class Meta:
model = HoursDay
class HoursSerializationSchema(ma.ModelSchema):
class Meta:
model = Hours
day = fields.Nested(HoursDaySerializationSchema)
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)
if __name__ == "__main__":
hour = {
'day': {
'name': 'monday'
}
}
loaded_hour, error = HoursSerializationSchema().load(hour) # this works
new_practitioner_at_location = {
'hours': [
hour
]
}
loaded, error = PractitionerToServiceLocationSerializationSchema().load(new_practitioner_at_location) # this fails
print('hi')
更新:
我认为发生的事情是棉花糖在尝试反序列化 new_practitioner_at_location
字典时没有尝试反序列化 HoursDay
对象。如果我从 HoursDay.hour
字段中删除 backpopulates
行为,那么您可以看到它只是将未序列化的数据结构分配给该字段。这对我来说毫无意义,特别是因为当你直接反序列化 hour
字典而不是将它嵌入 new_practitioner_at_location
中时它会起作用。
任何帮助,将不胜感激。
这是一个简单的类似拼写错误的错误:
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)
您正在 class Meta
内定义 hours
,但它需要在您的模式本身中:
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)
我正在尝试用棉花糖反序列化深层结构。例如:
hour = {
'day': {
'name': 'monday'
}
}
loaded_hour, error = HoursSerializationSchema().load(hour) # this works
new_practitioner_at_location = {
'hours': [
hour
]
}
loaded, error = PractitionerToServiceLocationSerializationSchema().load(new_practitioner_at_location) # this fails
当我尝试反序列化 new_practitioner_at_location
时,我得到以下信息(在序列化程序处理 'day' 键时发生):
AttributeError: 'dict' object has no attribute '_sa_instance_state'
请注意,当该结构未嵌套在 new_practitioner_at_location
内时,相同的模式用于反序列化相同的数据结构(小时)。
显示问题的独立脚本:
from sqlalchemy import Column, Integer, ForeignKey, String
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base
import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from flask_migrate import Migrate
base = declarative_base()
class HoursDay(base):
__tablename__ = 'HoursDay'
uid = Column(Integer, primary_key=True)
name = Column(String)
hour_id = Column(Integer, ForeignKey('Hours.uid'))
hour = relationship("Hours", back_populates="day")
def __init__(self, **kwargs):
super().__init__(**kwargs)
class Hours(base):
__tablename__ = 'Hours'
uid = Column(Integer, primary_key=True)
practitioner_at_location_id = Column(Integer, ForeignKey('PractitionerToServiceLocation.uid'))
practitioner_at_location = relationship('PractitionerToServiceLocation', back_populates="hours")
day = relationship(HoursDay, uselist=False, back_populates="hour")
def __repr__(self):
return f'<Hours {self.uid}>'
class PractitionerToServiceLocation(base):
"""
A practitioner practices at a number of service locations.
"""
__tablename__ = 'PractitionerToServiceLocation'
uid = Column(Integer, primary_key=True)
hours = relationship("Hours", back_populates="practitioner_at_location")
def __init__(self, **kwargs):
super().__init__(**kwargs)
def __repr__(self):
return f'<PractitionerToServiceLocation {self.uid}>'
app = Flask(__name__)
app.config.from_object(os.environ['APP_SETTINGS'])
db = SQLAlchemy(app, model_class=base)
ma = Marshmallow(app)
migrate = Migrate(app, db)
from marshmallow import fields
class HoursDaySerializationSchema(ma.ModelSchema):
class Meta:
model = HoursDay
class HoursSerializationSchema(ma.ModelSchema):
class Meta:
model = Hours
day = fields.Nested(HoursDaySerializationSchema)
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)
if __name__ == "__main__":
hour = {
'day': {
'name': 'monday'
}
}
loaded_hour, error = HoursSerializationSchema().load(hour) # this works
new_practitioner_at_location = {
'hours': [
hour
]
}
loaded, error = PractitionerToServiceLocationSerializationSchema().load(new_practitioner_at_location) # this fails
print('hi')
更新:
我认为发生的事情是棉花糖在尝试反序列化 new_practitioner_at_location
字典时没有尝试反序列化 HoursDay
对象。如果我从 HoursDay.hour
字段中删除 backpopulates
行为,那么您可以看到它只是将未序列化的数据结构分配给该字段。这对我来说毫无意义,特别是因为当你直接反序列化 hour
字典而不是将它嵌入 new_practitioner_at_location
中时它会起作用。
任何帮助,将不胜感激。
这是一个简单的类似拼写错误的错误:
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)
您正在 class Meta
内定义 hours
,但它需要在您的模式本身中:
class PractitionerToServiceLocationSerializationSchema(ma.ModelSchema):
class Meta:
model = PractitionerToServiceLocation
hours = fields.Nested('HoursSerializationSchema', many=True)