RESTful APIs (Create, Read) with flask-restful

I wrote this simple API to be able to send logs from the client to MongoDB. Even though this works and fits my need, I would like to point out some concerns that I have regarding the following:

• Is it efficient to be calling the instance of MongoClient for every request?

• Do I need to close the instance of MongoClient after the request is successful?

• A more Pythonic way to return responses?

```
from flask import Flask, jsonify, request, Response
from flask_restful import Resource, Api
from pymongo import MongoClient
import json

app = Flask(__name__)
api = Api(app)

USER = "user"
PASS = "pw"
MONGO_URI = 'mongodb://%s:%s@test.mlab.com/test' % (USER, PASS)
PORT = 19788

def db_conn():
client = MongoClient(MONGO_URI, PORT)
return client

def insert_record(args):
client = db_conn()
replycode = 0
try:
db = client['test']
posts = db.users
posts.insert(args)
except:
replycode = 1

return replycode

def select_record(args={}):

client = db_conn()
db = client['test']
result = db.users.find(args)
return result

class CreatUser(Resource):

def post(self):
try:
content = request.get_json()
if "Vehicle" not in content:
return jsonify({"Result": "Vehicle number not in passed arguments"}), 400

else:
vehicle = content['Vehicle']

reply = insert_record(content)
if reply == 0:
return jsonify({"Result" : "Successfully inserted user: " + vehicle}), 201
else:
return jsonify({"Result" : "Failed to insert data. Check logs for more details"}), 400

except Exception as e:
return jsonify({'Error' : str(e)}), 500

class ViewUser(Resource):
def get(self):
from bson import json_util

results = select_record()
final = []
for result in results:
result.pop("_id")
final.append(result)

The MongoClient was designed to be instantiated once per app life cycle, so this is redundant. You should try to reuse MongoClient instances as much as possible. Basically the only reason to create a new instance is if you want to configure it in a different way.

Also you've mentioned your API is supposed to be RESTful, so a few notes here:

1) To deal with user resource you should include it in the uri in pluralize form and distinguish actions you are performing by standard http codes, like the following:

/api/users POST - to create a new user

/api/users/{userId} GET - to fetch an existing one by userId

2) when you a new user is created it is a good practise to return 201 (Created) http code together with the full url to fetch the user which has been just created, like: http://yourdomain.com/api/users/{userId}

3) "Failed to insert data. Check logs for more details" - it doesn't look like a 400 Bad Request, as the user didn't make any mistake with input params. I suppose it must be either 500 (if the issue is related to something like a database error for example) or 403 Forbidden if any of implicit domain rules has been violated

Hope this helps

StackExchange Code Review Q#151824, answer score: 3