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creating a webservice in flask that queries a Mysql database and returns json

Please help:
I am trying to create a webservice in flask (this is my first time) that takes a str, queries an external mysql database and returns 1 row as json.
I am sure there are other of issues with the code below (all suggestions much appreciated), but I cannot even see them yet, because when I try to access example.com/webservice/vin/ I get "Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application." from nginx.
PLease can someone guide me where I am going wrong?
example.com return Hello from app_name running in docker...yayy. Its the other route that isnt working.
from flask.ext.mysqldb import MySQL
import json
app.config['MYSQL_HOST'] = 'xxx'
app.config['MYSQL_USER'] = 'xxx'
app.config['MYSQL_PASSWORD'] = 'xxx'
app.config['MYSQL_DB'] = 'xxx'
mysql = MySQL(app)
#app.route("/")
def index():
# Use os.getenv("key") to get environment variables
app_name = os.getenv("APP_NAME")
if app_name:
return f"Hello from {app_name} running in a Docker container behind Nginx!"
return "Hello from Flask"
#app.route('/webservice/vin/<vin>', methods=['GET'])
def get_vehicle(vin):
sql = "SELECT * FROM `table` where column = '(%s )';" %(vin)
cur = mysql.connection.cursor()
cur.execute(sql)
row_headers=[x[0] for x in cur.description] #this will extract row headers
rv = cur.fetchall()
json_data=[]
for result in rv:
json_data.append(dict(zip(row_headers,result)))
return json.dumps(json_data)
from flask import make_response
#app.errorhandler(404)
def not_found(error):
return make_response(jsonify({'error': 'Not found'}), 404)

Flask API facing InterfaceError with PostgreSQL

I have a Flask API based on Flask RestPlus extension and is hosted on Google App Engine. The API does a basic job of fetching data from a Google Cloud SQL PostgreSQL. The API is working fine otherwise but sometimes it starts returning InterfaceError: cursor already closed.
Strangely, when I do a gcloud app deploy, the API starts working fine again.
Here's a basic format of the API:
import simplejson as json
import psycopg2
from flask import Flask, jsonify
from flask_restplus import Api, Resource, fields
from psycopg2.extras import RealDictCursor
app = Flask(__name__)
app.config['SWAGGER_UI_JSONEDITOR'] = True
api = Api(app=app,
doc='/docs',
version="1.0",
title="Title",
description="description")
app.config['SWAGGER_UI_JSONEDITOR'] = True
ns_pricing = api.namespace('cropPricing')
db_user = "xxxx"
db_pass = "xxxx"
db_name = "xxxxx"
cloud_sql_connection_name = "xxxxxx"
conn = psycopg2.connect(user=db_user,
password=db_pass,
host='xxxxx',
dbname=db_name)
#ns_pricing.route('/list')
class States(Resource):
def get(self):
"""
list all the states for which data is available
"""
cur = conn.cursor(cursor_factory=RealDictCursor)
query = """
SELECT
DISTINCT state
FROM
db.table
"""
conn.commit()
cur.execute(query)
states = json.loads(json.dumps(cur.fetchall()))
if len(states) == 0:
return jsonify(data=[],
status="Error",
message="Requested data not found")
else:
return jsonify(status="Success",
message="Successfully retreived states",
data=states)
What should I fix to not see the error anymore?

It would be good to use the ORMs such as SQLAlchemy / Flask-SQLAlchemy which would handle the establishing / re-establishing the connection part.
Though, if using psycopg2. you can use try except to catch the exception and re-establish the connection again.
try:
cur.execute(query)
except psycopg2.InterfaceError as err:
print err.message
conn = psycopg2.connect(....)
cur = conn.cursor()
cur.execute(query)

Flask update on refresh with data from MySQL

I am trying to make webpage with flask which displays data from mysql table. My code is:
#app.route("/")
def index():
cursor = db.cursor()
cursor.execute('SELECT * from private')
privateDB = cursor.fetchall()
cursor.close()
return render_template('index.html', t=privateDB)
However whenever I refresh the page I get old data, it doesn't fetch new updated data. How to fix? Thank you.

Try it with this code
#app.route("/")
def index():
connection = mysql.connect()
cursor = connection.cursor()
cursor.execute("SELECT * from private")
data = cursor.fetchall()
return render_template('index.html', data=data)

REST API for Azure SQL DB on Linux Machine

Question. I would like to create a REST API for the data stored in an Azure SQL DB that will allow me to do GET and POST operation using Python. Currently I managed to print the results of my query on the terminal but how do I convert it to JSON format and allow it to run 24/7 on linux (perhaps change port?)? Below is my script:
import pyodbc
from flask import Flask, jsonify, request
from flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class Energy(Resource):
def get(self):
server = 'testserver.database.windows.net'
database = 'testdb'
username = 'admin'
password = '735t'
driver= '{ODBC Driver 13 for SQL Server}'
connexion = pyodbc.connect('DRIVER='+driver+';PORT=1433;SERVER='+server+';PORT=1443;DATABASE='+database+';UID='+username+';PWD='+ password)
cursor = connexion.cursor()
cursor.execute("SELECT TOP (100) * FROM [dbo].[Power_Meter]")
row = cursor.fetchone()
while row:
GeneratedCode = str(row[0])
ReportedDate = str(row[1])
print (str(row[0]) + " " + str(row[1]))
row = cursor.fetchone()
rest_row = jsonify(row)
return rest_row
api.add_resource(Energy, '/DPM')
if __name__ == '__main__':
app.run(debug=True)
and this is the output result on localhost:5000/DPM
null
Can anyone suggest me how to go about solving this issue? Thanks

If you want to run your script 24/7 on Linux, you could execute it as a background task. Using nohup python sql.py>> test.log &
man nohup
nohup - run a command immune to hangups, with output to a non-tty
& to the command line to run in the background:
If you want to change port, just change like below:
app.run(host='0.0.0.0',port=5000)
I suggest you could store output to a file. Then you could parse data to json format.

Flask mysql getting response to SQL commands (not using SQL-Alchemy)

First, I understand the value of using ORM solutions, and will use SQL-Alchemy later.
I have installed Flask and am using flask-mysql.
I do not know how to get the results for a SQL "desc " command.
Here is the code I'm working with:
from flask import Flask, render_template, request, redirect, jsonify
import requests
from flaskext.mysql import MySQL
app = Flask(__name__)
#app.route("/")
def main():
return render_template('login.html')
#app.route("/login", methods=['POST'])
def login():
#username = request.form['username'] #not using the form fields yet
#password = request.form['password']
mysql = MySQL()
app.config['MYSQL_DATABASE_USER'] = '<my user here>'
app.config['MYSQL_DATABASE_PASSWORD'] = '<password here>'
app.config['MYSQL_DATABASE_DB'] = '<database name here>'
app.config['MYSQL_DATABASE_HOST'] = '<database server IP address here>'
mysql.init_app(app)
conn = mysql.connect()
cursor = conn.cursor()
#cursor = mysql.connection.cursor() #invalid code, at least for this version of flask-mysql
cursor.execute("desc user;")
result = jsonify(cursor.fetchall())
#row = cursor.fetchone()
return "<!DOCTYPE html><html><body>" + str(result)+ "</body></html>"
if __name__ == "__main__":
app.run()
It appears to be connecting to the database, logging in, and sending the desc command OK because result's contents are "Response 268 bytes [200 OK]" (can see that by looking at the page source code after getting the response in the browser).
Is there any way to get the results (table description) and not just an "OK I ran this command"?
Thank you.

I suppose you would like to get all records and sort them in desc order. You may try this.
from flask_mysqldb import MySQL
app.config['MYSQL_HOST'] = 'localhost'
app.config['MYSQL_USER'] = 'root'
app.config['MYSQL_PASSWORD'] =
app.config['MYSQL_DB'] =
app.config['MYSQL_CURSORCLASS'] = 'DictCursor'
# initialize mysql
mysql = MySQL(app)
...
#app.route('/posts')
def posts():
cur = mysql.connection.cursor()
result = cur.execute('SELECT * FROM posts ORDER BY postdate DESC ')
posts = cur.fetchall()
if result > 0:
return render_template('posts.html', posts=posts)
else:
message = 'I shouldn't find any post'
return render_template('posts.html', message=message)
cur.close