object不是JSON可序列化的

Question

我在使用Mongodb和Python(Flask)时遇到了一些麻烦.

我有这个api.py文件,我希望所有的请求和响应都是JSON,所以我这样实现.

#
# 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,所以那很好......问题是/ show.这段代码不起作用......当我做一些日志记录时,我得到了

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

有任何想法吗？我也欢迎任何有关其余代码的建议,但JSON正在扼杀我.

提前致谢!

Answer 1

虽然@ErenGüven向您展示了一个很好的手动方法来解决这个json序列化问题,但是pymongo附带了一个实用程序来为您完成此任务.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)

或者干脆:

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

并让他们再次从json回来:

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

帮助程序实用程序告诉json如何处理自定义mongodb对象.

Answer 2

当您传递db.units.find()给对象时,response将pymongo.cursor.Cursor对象传递给json.dumps...并且json.dumps不知道如何将其序列化为JSON.尝试通过迭代光标来获取实际对象以获得其结果:

[doc for doc in db.units.find()]

Answer 3

import json
from bson import json_util

docs_list  = list(db.units.find())
return json.dumps(docs_list, default=json_util.default)