TypeError：mappingproxy 类型的对象不是 JSON 可序列化的

Posted 2023-03-29

【中文标题】TypeError：mappingproxy 类型的对象不是 JSON 可序列化的

【英文标题】：TypeError: Object of type mappingproxy is not JSON serializable

【发布时间】：2021-12-10 05:29:46

【问题描述】：

我在尝试将类对象转换为 JSON 格式时遇到问题。 实际上，我有一个 ECG 类对象，我希望将该对象转换为 JSON 格式的字符串。

例如：“Source”：“MIT”，“FileName”：“100”，“Channel”：2，“Record”：11520000，“Time”：1800，“SampleRate”：500

ECGModel.py

class ECG(object):
@classmethod
def __init__(self, source, fileName, channel, record, time, sampleRate, ecg):
    self.Source = source
    self.FileName = fileName
    self.Channel = channel
    self.Record = record
    self.Time = time
    self.SampleRate = sampleRate
    self.ECG = ecg

# getting the values
@property
def value(self):
    print('Getting value')
    return self.Source, self.FileName, self.Channel, self.Record, self.Time, self.SampleRate, self.ECG

# setting the values
@value.setter
def value(self, source, fileName, channel, record, time, sampleRate, ecg):
    print('Setting value to ' + source)
    self.Source = source
    self.FileName = fileName
    self.Channel = channel
    self.Record = record
    self.Time = time
    self.SampleRate = sampleRate
    self.ECG = ecg

# deleting the values
@value.deleter
def value(self):
    print('Deleting value')
    del self.Source, self.Source, self.FileName, self.Channel, self.Record, self.Time, self.SampleRate, self.ECG

main.py

import streamlit as st
import Processor as processor
import json

ecgProperty = processor.GetSourceProperty(r"C:\Users\100.dat")

st.write(type(ecgProperty))
st.write(ecgProperty)
jsonECGPropertyStr = json.dumps(ecgProperty.__dict__)
st.write(jsonECGPropertyStr)

处理器.py

import streamlit as st
import Controllers.ECGModel as ecgModel

def GetSourceProperty(filePath):
    ecg = ecgModel.ECG
    ecg.Source = "MIT"
    ecg.FileName = "100"
    ecg.Channel = 2
    ecg.Record = 11520000
    ecg.Time = 1800
    ecg.SampleRate = 500
    return ecg

日志：

<class 'type'>
<class 'Controllers.ECGModel.ECG'>
File "C:\Users\xxx\AppData\Local\Programs\Python\Python39\lib\site-packages\streamlit\script_runner.py", line 354, in _run_script
    exec(code, module.__dict__)
File "D:\SourceCode\BIS2019_MasterThesis\ECG_Evaluation\Main.py", line 27, in <module>
    jsonECGPropertyStr = json.dumps(ecgProperty.__dict__)
File "C:\Users\xxx\AppData\Local\Programs\Python\Python39\lib\json\__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
File "C:\Users\xxx\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
File "C:\Users\xxx\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
File "C:\Users\xxx\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 179, in default
    raise TypeError(f'Object of type o.__class__.__name__ '
TypeError: Object of type mappingproxy is not JSON serializable

【问题讨论】：

json.dumps(ecgProperty.__dict__) 的预期输出是什么？包含 source, FileName, ... 值的 json 字符串？

@ShihabusSakibRad 是的，没错

【参考方案1】：

我试图猜测您要达到的目标。看看下面的代码是否适合你

ECGModel.py

class ECG:
    def __init__(self, source, file_name, channel, record, time, sample_rate):
        self.source = source
        self.file_name = file_name
        self.channel = channel
        self.record = record
        self.time = time
        self.sample_rate = sample_rate

处理器.py

from ECGModel import ECG


def GetSourceProperty():
    return ECG(source="MIT", file_name="100", channel=2, record=11520000, time=1800, sample_rate=500)

主要.py： 您可以将print 替换为您的st.write

import Processor
import json

ecg = Processor.GetSourceProperty()

print(type(ecg))
print(ecg)
print(json.dumps(ecg.__dict__))

输出

<class 'ECGModel.ECG'>
<ECGModel.ECG object at 0x000002ED4E82B670>
"source": "MIT", "file_name": "100", "channel": 2, "record": 11520000, "time": 1800, "sample_rate": 500

【讨论】：

谢谢。我在我的代码中发现了 2 个问题。 1. @classmethod 引起了问题（如果我把它放在那里，输出将为空）。 2. 所有属性都必须像它们的参数一样——self.source = source——应该是“source”而不是“Source”

@HuyDQ 不，属性名称与参数名称相同不是强制性的。你可以做self.source_name = source，在这种情况下，Json 将包含source_name。如果你是 python 新手，你可以阅读关于classmethod、init、attribute name