TypeError:类型为ObjectId的对象不可JSON序列化 [英] TypeError: Object of type ObjectId is not JSON serializable
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问题描述
我一直在开发一个简单的app.py，下面是代码:
from flask import Flask, request, jsonify, make_response
from pymongo import MongoClient
from bson import ObjectId
app = Flask(__name__)
client = MongoClient("mongodb://127.0.0.1:27017")
db = client.bizDB
businesses = db.biz
@app.route("/api/v1.0/businesses", methods=["GET"])
def show_all_businesses():
page_num, page_size = 1, 10
if request.args.get("pn"):
page_num = int(request.args.get("pn"))
if request.args.get("ps"):
page_size = int(request.args.get("ps"))
page_start = page_size * (page_num - 1)
data_to_return = []
for business in businesses.find().skip(page_start).limit(page_size):
business["_id"] = str(business["_id"])
for review in business["reviews"]:
review["_id"] = str(review["_id"])
data_to_return.append(business)
return make_response(jsonify(data_to_return), 200)
@app.route("/api/v1.0/businesses/<string:id>", methods=["GET"])
def show_one_business(id):
business = businesses.find_one({"_id": ObjectId(id)})
if business is not None:
business["_id"] = str(business["_id"])
for review in business["reviews"]:
review["_id"] = str(review["_id"])
return make_response(jsonify(business), 200)
else:
return make_response(jsonify({"error": "Invalid Business ID"}), 404)
@app.route("/api/v1.0/businesses", methods=["POST"])
def add_business():
if "name" in request.form and "town" in request.form and "rating" in request.form:
new_business = {"name": request.form["name"],
"town": request.form["town"],
"rating": request.form["rating"],
"reviews": {}
}
new_business_id = businesses.insert_one(new_business)
new_business_link = "http://localhost:5000/api/v1.0/businesses/" + \
str(new_business_id.inserted_id)
return make_response(jsonify({"url": new_business_link}), 201)
else:
return make_response(jsonify({"error": "Missing form data"}), 404)
@app.route("/api/v1.0/businesses/<string:id>", methods=["PUT"])
def edit_business(id):
if "name" in request.form and "town" in request.form and "rating" in request.form:
result = businesses.update_one(
{"_id": ObjectId(id)},
{
"$set": {
"name": request.form["name"],
"town": request.form["town"],
"rating": request.form["rating"]
}
}
)
if result.matched_count == 1:
edited_business_link = "http://localhost:5000/api/v1.0/businesses/" + id
return make_response(jsonify({"url": edited_business_link}), 200)
else:
return make_response(jsonify({"error": "Invalid business ID"}), 404)
else:
return make_response(jsonify({"error": "Missing form data"}), 404)
@app.route("/api/v1.0/businesses/<string:id>", methods=["DELETE"])
def delete_business(id):
result = businesses.delete_one({"_id": ObjectId(id)})
if result.deleted_count == 1:
return make_response(jsonify({}), 200)
else:
return make_response(jsonify({"error": "Invalid business ID"}), 404)
@app.route("/api/v1.0/businesses/<string:id>/reviews", methods=["POST"])
def add_new_review(id):
new_review = {
"_id": ObjectId(),
"username": request.form["username"],
"comment": request.form["comment"],
"stars": request.form["stars"]
}
businesses.update_one({"_id": ObjectId(id)}, {
"$push": {"reviews ": new_review}})
new_review_link = "http://localhost:5000/api/v1.0/businesses/" + \
id + "/reviews/" + str(new_review["_id"])
return make_response(jsonify({"url": new_review_link}), 201)
if __name__ == "__main__":
app.run(debug=True)
Eveyrthing一直运行良好，直到在VS Code中我意外地在文件上单击了格式文档，Postman先前从mongoDB返回了我的结果，但是现在我收到TypeError错误:ObjectId类型的对象不可JSON序列化. >
我不知道如何解决此问题或问题所在.
解决方案
您的根本原因是，在您返回的响应中，对象包含类型为ObjectId的字段，该字段始终为_id字段.
要全面修复它，请使用我们自己的自定义JSON编码器，该编码器会自动将ObjectId转换为字符串.有了这些代码后，您的代码就会变得很整洁，因为您可以删除所有需要手动进行转换的代码.
编码器示例如下:
class MyEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, ObjectId):
return str(obj)
return super(MyEncoder, self).default(obj)
然后让flask知道如何将其用于:
app.json_encoder = MyEncoder
将所有内容放在一起作为一个最小的示例是:
from pymongo import MongoClient
from flask import Flask, jsonify
from bson.json_util import ObjectId
import json
class MyEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, ObjectId):
return str(obj)
return super(MyEncoder, self).default(obj)
db = MongoClient()['mydatabase']
app = Flask(__name__)
app.json_encoder = MyEncoder
with app.test_request_context():
db.mycollection.insert_one({'a': 1})
doc = db.mycollection.find_one({'a': 1})
print(jsonify(doc).response)
打印:
[b'{"_id":"5ff055dffab2033526bd0b63","a":1}\n']
注意:如果您注释掉app.json_encoder = MyEncoder行，则会重现您的错误:
return _json.JSONEncoder.default(self, o)
File "C:\Python38\lib\json\encoder.py", line 179, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type ObjectId is not JSON serializable
I have been developing a simple app.py, here is the code:
from flask import Flask, request, jsonify, make_response
from pymongo import MongoClient
from bson import ObjectId
app = Flask(__name__)
client = MongoClient("mongodb://127.0.0.1:27017")
db = client.bizDB
businesses = db.biz
@app.route("/api/v1.0/businesses", methods=["GET"])
def show_all_businesses():
page_num, page_size = 1, 10
if request.args.get("pn"):
page_num = int(request.args.get("pn"))
if request.args.get("ps"):
page_size = int(request.args.get("ps"))
page_start = page_size * (page_num - 1)
data_to_return = []
for business in businesses.find().skip(page_start).limit(page_size):
business["_id"] = str(business["_id"])
for review in business["reviews"]:
review["_id"] = str(review["_id"])
data_to_return.append(business)
return make_response(jsonify(data_to_return), 200)
@app.route("/api/v1.0/businesses/<string:id>", methods=["GET"])
def show_one_business(id):
business = businesses.find_one({"_id": ObjectId(id)})
if business is not None:
business["_id"] = str(business["_id"])
for review in business["reviews"]:
review["_id"] = str(review["_id"])
return make_response(jsonify(business), 200)
else:
return make_response(jsonify({"error": "Invalid Business ID"}), 404)
@app.route("/api/v1.0/businesses", methods=["POST"])
def add_business():
if "name" in request.form and "town" in request.form and "rating" in request.form:
new_business = {"name": request.form["name"],
"town": request.form["town"],
"rating": request.form["rating"],
"reviews": {}
}
new_business_id = businesses.insert_one(new_business)
new_business_link = "http://localhost:5000/api/v1.0/businesses/" + \
str(new_business_id.inserted_id)
return make_response(jsonify({"url": new_business_link}), 201)
else:
return make_response(jsonify({"error": "Missing form data"}), 404)
@app.route("/api/v1.0/businesses/<string:id>", methods=["PUT"])
def edit_business(id):
if "name" in request.form and "town" in request.form and "rating" in request.form:
result = businesses.update_one(
{"_id": ObjectId(id)},
{
"$set": {
"name": request.form["name"],
"town": request.form["town"],
"rating": request.form["rating"]
}
}
)
if result.matched_count == 1:
edited_business_link = "http://localhost:5000/api/v1.0/businesses/" + id
return make_response(jsonify({"url": edited_business_link}), 200)
else:
return make_response(jsonify({"error": "Invalid business ID"}), 404)
else:
return make_response(jsonify({"error": "Missing form data"}), 404)
@app.route("/api/v1.0/businesses/<string:id>", methods=["DELETE"])
def delete_business(id):
result = businesses.delete_one({"_id": ObjectId(id)})
if result.deleted_count == 1:
return make_response(jsonify({}), 200)
else:
return make_response(jsonify({"error": "Invalid business ID"}), 404)
@app.route("/api/v1.0/businesses/<string:id>/reviews", methods=["POST"])
def add_new_review(id):
new_review = {
"_id": ObjectId(),
"username": request.form["username"],
"comment": request.form["comment"],
"stars": request.form["stars"]
}
businesses.update_one({"_id": ObjectId(id)}, {
"$push": {"reviews ": new_review}})
new_review_link = "http://localhost:5000/api/v1.0/businesses/" + \
id + "/reviews/" + str(new_review["_id"])
return make_response(jsonify({"url": new_review_link}), 201)
if __name__ == "__main__":
app.run(debug=True)
Eveyrthing has been working fine up until in VS Code I clicked format document by accident on the file, Postman previously returned my results from mongoDB but now I receive an error of TypeError: Object of type ObjectId is not JSON serializable.
I don't know how to fix this issue or what the problem is.
解决方案
Your root cause is that in the responses you are returning, the object contains a field of type ObjectId which is invariably the _id field.
To fix it across the board, use our own custom JSON encoder that automatically converts the ObjectIds to strings. Once you have this your code tidies up a lot because you can remove all the code where you are manually needing to do the conversion.
An example encoder looks like:
class MyEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, ObjectId):
return str(obj)
return super(MyEncoder, self).default(obj)
And you let flask know to use it with:
app.json_encoder = MyEncoder
Putting it all together a minimal example would be:
from pymongo import MongoClient
from flask import Flask, jsonify
from bson.json_util import ObjectId
import json
class MyEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, ObjectId):
return str(obj)
return super(MyEncoder, self).default(obj)
db = MongoClient()['mydatabase']
app = Flask(__name__)
app.json_encoder = MyEncoder
with app.test_request_context():
db.mycollection.insert_one({'a': 1})
doc = db.mycollection.find_one({'a': 1})
print(jsonify(doc).response)
prints:
[b'{"_id":"5ff055dffab2033526bd0b63","a":1}\n']
Note: If you comment out the line app.json_encoder = MyEncoder you reproduce your error:
return _json.JSONEncoder.default(self, o)
File "C:\Python38\lib\json\encoder.py", line 179, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type ObjectId is not JSON serializable
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