python - 对象不是 JSON 可序列化的

Question

我在使用 Mongodb 和 Python (Flask) 时遇到了一些问题。

我有这个 api.py 文件，我希望所有请求和响应都使用 JSON 格式，所以我就这样实现了。

#
# Imports
#

from datetime import datetime
from flask import Flask
from flask import g
from flask import jsonify
from flask import json
from flask import request
from flask import url_for
from flask import redirect
from flask import render_template
from flask import make_response
import pymongo
from pymongo import Connection
from bson import BSON
from bson import json_util

#
# App Create
#

app = Flask(__name__)
app.config.from_object(__name__)

#
# Database
#

# connect
connection = Connection()
db = connection['storage']
units = db['storage']


#
# Request Mixins
#

@app.before_request
def before_request():
    #before
    return

@app.teardown_request
def teardown_request(exception):
    #after
    return


#
# Functions
#

def isInt(n):
    try:
        num = int(n)
        return True
    except ValueError:
        return False

def isFloat(n):
    try:
        num = float(n)
        return True
    except ValueError:
        return False

def jd(obj):
    return json.dumps(obj, default=json_util.default)

def jl(obj):
    return json.loads(obj, object_hook=json_util.object_hook)

#
# Response
#

def response(data={}, code=200):
    resp = {
        "code" : code,
        "data" : data
    }
    response = make_response(jd(resp))
    response.headers['Status Code'] = resp['code']
    response.headers['Content-Type'] = "application/json"
    return response


#
# REST API calls
#

# index
@app.route('/')
def index():
    return response()

# search
@app.route('/search', methods=['POST'])
def search(): 
    return response()

# add
@app.route('/add', methods=['POST'])
def add():
    unit = request.json
    _id = units.save(unit)
    return response(_id)

# get
@app.route('/show', methods=['GET'])
def show():
    import pdb; pdb.set_trace();
    return response(db.units.find())

#
# Error handing
#

@app.errorhandler(404)
def page_not_found(error):
    return response({},404)


#
# Run it!
#

if __name__ == '__main__':
    app.debug = True
    app.run()

这里的问题是来自 mongo 的 json 编码数据。看来我已经能够通过将 request.json 作为保存字典来“破解”添加路由，所以这很好......问题是/show。此代码不起作用...当我进行一些日志记录时，我得到了

TypeError: <pymongo.cursor.Cursor object at 0x109bda150> is not JSON serializable

有什么想法吗？我也欢迎对其余代码提出任何建议，但 JSON 让我很头疼。

提前致谢!

Answer 1

@ErenGüven 向您展示了一种很好的手动方法来解决这个 json 序列化问题，而 pymongo 带有 utility to accomplish this for you .我在自己的 django mongodb 项目中使用它:

import json
from bson import json_util

json_docs = []
for doc in cursor:
    json_doc = json.dumps(doc, default=json_util.default)
    json_docs.append(json_doc)

或者简单地说:

json_docs = [json.dumps(doc, default=json_util.default) for doc in cursor]

并再次从 json 中取回它们:

docs = [json.loads(j_doc, object_hook=json_util.object_hook) for j_doc in json_docs]

帮助实用程序告诉 json 如何处理自定义 mongodb 对象。