Fetch Data from Snowflake to nodejs - javascript

I am trying to design an API using Snowflake and Nodejs. For that I am using the following things :
Express
ejs
snowflake-sdk (nodejs module)
I want to fetch data from snowflake and want to display it on my ejs webpage. Please help if anyone has fetched data and populated it on a webpage using nodejs and snowflake.
this is my server.js file
const express = require("express");
const app= express();
const sql = require("./snowflake");
app.use(express.static("public"));
app.use(express.urlencoded({ extended: true}));
app.set("view engine","ejs");
app.get("/", function(request,response){
response.render("index");
});
app.get("/request/:core", async function(request,response){
let core=await sql.getCore(request.params.core_name);
response.render("request",{request: core});
});
const http = require('http');
const port=3000;
const server=http.createServer(function(req,res){
})
const listener = app.listen(port,function(error){
if(error){
console.log("Something went wrong due :", error);
}
else{
console.log('Server is listening port '+port);
}
})
This is my database.js file. I am able to connect to snowflake and run queries but can't understand, how to fetch the query result on the ejs webpage.
const { initParams } = require('request');
const sql = require('snowflake-sdk');
const connection = sql.createConnection({
account: 'account_name',
authenticator: 'SNOWFLAKE',
username: 'username',
password: 'password',
database: 'database',
schema: 'schema'
});
module.exports.getCore = async() =>{
connection.execute({
sqlText: 'Select column from Table_name',
complete: async function(err,stmt,rows){
let pool= await sql.connect();
return rows;
}
})
}

There is a sample application that you can try to compare, is written on node.js. It is a Citi Bike dashboard that lets users view bike usage over time and in differing weather conditions. The source code is available on GitHub.
More details: https://quickstarts.snowflake.com/guide/data_app/#4

Related

express API extract data from URL

My api recives every 45 minutes a request:
GET http://MyHost/mediciones/sigfox_libelium/{device}/{data}/{time}/{customData#trama}
I want my code to save {device}, {data}, {time} and {customData#trama} into different variables so I can parse it into readable values(all data it is send hexadecimal) and insert them into my database.
How do I take those values out of the URL?
Also, what is the purpose of req, res? I guess It stands for request, respond.Respond sends back to the client but, request? I dont really understand how it works. Im learning all this new, hope someone can help.
This is my API code, I tried it with postman and it works fine so far:
const express = require("express");
const bodyParser = require("body-parser");
const cors = require("cors");
const Pool = require("pg").Pool;
const pool = new Pool({
user: "mgr#stanpgtest",
host: "stanpgtest.postgres.database.azure.com",
database: "my db name",
password: "my pass",
port: 5432
});
const app = express();
app.use(cors());
app.use(bodyParser.json());
app.listen(8000, () => {
console.log(`Server is running, listening to port 8000`);
});
app.post("mediciones/sigfox_libelium/{device}/{data}/{time}/{customData#trama}", (req, res) => {
const { label, status, priority } = req.body;
pool.query(
"select now()",
(error, results) => {
if (error) {
throw error;
}
res.send(results);
}
);
});
You need to write the path in this format, then extract your params from req.params.
app.post("mediciones/sigfox_libelium/:device/:data/:time/:customData", (req, res) => {
const {device, data, time, customData} = req.params
}
I'm not sure what #trama is meant to be, but I guess you can't use # in the route pattern.

adding mongoDB to web app that is working with postgreSQL

I have a simple web applicatoin with nodeJS backend and postgreSQL database.
I need to add a mongoDB database that will also save the state off the application as backup.
Is it possible to add it without changing the app structure in a simple way?
my code:
postgres.js file:
const Pool = require('pg').Pool
const pool = new Pool({
user: 'postgres',
host: 'localhost'
database: 'tasks',
password: 'password',
port: 5432,
});
const getTasks = (request, response) => {
// get tasks query
};
const getTaskById = (request, response) => {
// get task by id query
};
const createTask = (request, response) => {
// create task query
};
const updateTask = (request, response) => {
// update task query
};
const deleteTask = (request, response) => {
// delete task query
}
module.exports = {
getTasks,
getTaskById,
createTask,
updateTask,
deleteTask
};
index.js file:
const express = require('express')
const bodyParser = require('body-parser')
var cors = require('cors')
const app = express()
const port = 8080
const db = require('./db/postgres')
app.use(cors());
app.use(bodyParser.json());
app.use(
bodyParser.urlencoded({
extended: true,
})
);
app.get('/', (request, response) => {
response.json({ info: 'Node.js, Express, and Postgres API' })
});
app.get('/tasks', db.getTasks);
app.get('/tasks/:id', db.getTaskById);
app.post('/tasks', db.createTask);
app.put('/tasks/:id', db.updateTask);
app.delete('/tasks/:id', db.deleteTask);
app.listen(port, () => {
console.log(`App running on port ${port}.`)
});
Thanks!
How complicated is the state of the application and how do you intend on keeping it updated? Perhaps using MongoDB as store for state snapshots is over-complicating things. Storing JSON in Redis is possibly a simpler route.
You should perhaps also ask yourself why you need to save the sate of the application if you already have the postgres database. What state does your backend produce that is auxiliary to the data in postgres?

My app post data into JSON however it also throws this error "http://localhost:5000/write net::ERR_CONNECTION_RESET"

Sorry if I don't post the correct details, this is my first hands-on project after going through online tutorials.
I'm using React, node with axios to build a web app that captures status(available, in a meeting, lunch etc) and the time spent on each status.
The app works fine, it captures and writes the data onto the backend(JSON) however, I keep getting this error on the console.
POST https://localhost:5000/write net::ERR_CONNECTION_RESET
Uncaught (in promise) ERROR: Network Error
I've tried to look for a solution but can't find one that is similar to the tech-stack I used. Also, my lack of sufficient knowledge don't help either.
Any lead or read or solution will help.
pasting my code below:
My frontend code to push data into JSON file
const saveJson = (posts) => {
//api URL //end point from node server / express server
const url = "http://localhost:5000/write";
axios.post(url, posts).then((response) => {
//console.log(response);
}); };
The server.js code
const express = require("express");
const bodyParser = require("body-parser");
//calling packages
const fs = require("fs");
const morgan = require("morgan");
const cors = require("cors");
//Declare app
const app = express();
const port = 5000;
//middlewares
app.use(bodyParser.json());
app.use(morgan("dev"));
app.use(cors());
//default route for server
app.get("/", (req, res) =>
res.status(200).send({
message: "Server is running...",
})
);
const WriteTextToFileAsync = async (contentToWrite) => {
fs.writeFile("./src/data.json", contentToWrite, (err) => {
console.log(contenToWrite);
if (err) {
console.log(err);
} else {
console.log("Done writing to file...");
// res.json({ msg: "success" });
}
});
};
//Declare timerow/write route to accept incoming require with data
app.post("/write", async (req, res, next) => {
//take the body from incoming requestby using req.body and conver it into string
const requestContent = JSON.stringify(req.body);
await WriteTextToFileAsync(requestContent);
});
//404 route for server
app.use((req, res, next) =>
res.status(404).send({
message: "Could not find specified route requested...!",
})
);
//run server
app.listen(port, () => {
console.log(
`!!! server is running
!!! Listening for incoming requests on port ${port}
!!! http://localhost:5000
`
);
});

Cant connect to MongoDB in Firebase Functions

I am using Firebase Functions as the host for my MERN web app backend.
When I connect to MongoDB locally, it works and can run operations with the database. However, when I deployed to firebase functions, it failed to even connect to the database.
Code:
index.js
const functions = require('firebase-functions');
const server = require('./server.js');
exports.api = functions.runWith({ memory: "2GB", timeoutSeconds: 120 }).https.onRequest(server);
Part of server.js
const express = require("express");
const dotenv = require("dotenv");
const colors = require("colors");
const morgan = require("morgan");
const path = require("path");
const cors = require("cors");
const bodyParser = require("body-parser");
const routes = require("./routes/routes.js");
const mongooseMethods = require("./database.js");
dotenv.config({ path: "./config/config.env" });
mongooseMethods.connectDB(process.env.MONGO_URL);
const PORT = process.env.PORT || 8080;
// set up app
const app = express();
app.listen(PORT, console.log(`Server running in ${process.env.NODE_ENV} mode on port ${PORT}`.yellow.bold));
app.use(cors({ origin: true }));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(morgan("dev"));
app.use("/api", routes); // /api routes
module.exports = app;
routes.js
const express = require("express");
const app = express.Router();
const testingApi = require('../controller/testing.js');
const authApi = require('../controller/auth.js');
// testing
app.get('/testing', testingApi.testing);
// user authentication
app.post('/user/register', authApi.createUser);
module.exports = app;
api/testing/ also works
database.js
const mongoose = require("mongoose");
const mongooseMethods = {
connectDB: async (url) => {
try {
console.log("Connecting to MongoDB")
const connection = await mongoose.connect(url, { useNewUrlParser: true, useUnifiedTopology: true });
console.log(`MongoDB Connected: ${connection.connection.host}`.cyan.bold);
return connection;
} catch (error) {
console.log(`Error: ${error.message}, Exiting`.red.bold);
process.exit(1);
}
}
}
module.exports = mongooseMethods;
auth.js
const User = require('../model/user.model.js');
const bcrypt = require("bcryptjs");
let authenticationApi = {
createUser: async (req, res) => {
try {
console.log("Creating");
let newUser = new User({
...req.body
})
let result = await newUser.save();
return res.status(200).json({ result: result });
} catch (error) {
return res.status(400);
}
}
}
module.exports = authenticationApi;
The error I received when sending request to firebase is
2020-02-27T02:34:46.334044912Z D api: Function execution took 30970 ms, finished with status: 'connection error'
Yet it runs perfectly fine in local. I also don't see the console log "connected to MongoDB". I'm guessing that the problem occurs in database.js that it failed to connect to mongo at the first place yet I don't know how to solve.
I am using the paid plan in Firebase and the outbound networking should be fine.
p.s. this is my first time posting here. thanks for your time and I apologize in advance if i'm breaking any rules.
Listening on a port is not a valid operation in cloud functions:
app.listen(PORT, console.log(`Server running in ${process.env.NODE_ENV} mode on port ${PORT}`.yellow.bold));
Cloud Functions listens for you, using the URL that it was assigned, then delivers the request to your code. When you pass your express app to onRequest(), that's all wired up for you.
I suggest starting with a stripped down, simplified version of an app just to gain experience about how things work, then add in more as you get comfortable.
The reason for this to happen is that the architecture of Firebase Functions is not an actual server, but a serverless lambda-like endpoint. Since it cannot establish a lasting connection to the database, that it has to make a connection every time it received a request, the database sees this as spam and shut down further connection request from Firebase.
Therefore, you simply cannot host a complete express app with intended lasting connection in Firebase Functions.
More on that in this article

cannot connect to mongo local DB from Node JS

I am learning Mongo DB, Mongoose and Node JS and I can't seem to connect my Node JS to local Mongo DB.
Here is my code:
dbtest.js
var express = require('express');
var app = express(); // create our app w/ express
var mongoose = require('mongoose'); // mongoose for mongodb
var morgan = require('morgan'); // log requests to the console (express4)
var bodyParser = require('body-parser'); // pull information from HTML POST (express4)
var methodOverride = require('method-override'); // simulate DELETE and PUT (express4)
var options = {
useMongoClient: true,
autoIndex: false, // Don't build indexes
reconnectTries: Number.MAX_VALUE, // Never stop trying to reconnect
reconnectInterval: 500, // Reconnect every 500ms
poolSize: 10, // Maintain up to 10 socket connections
// If not connected, return errors immediately rather than waiting for reconnect
bufferMaxEntries: 0
};
var Todo = mongoose.model('Todo', {
text : String
}, 'test');
var status = {
"status": "not connected"
};
app.get('/api/todos', function(req, res) {
mongoose.connect('mongodb://127.0.0.1:27017/exampleDB',options,function(err)
{
if (err) {
res.json(status);
} else {
res.json('Connected');
}
});
});
app.listen(8080);
console.log("App listening on port 8080");
When I call api/todos GET request, the status JSON object is returned, meaning I cannot connect to the database.
I installed MongoDB Enterprise Server 3.14.10 completely and have it running but I don't know why my NodeJS application cannot connect.
Any suggestions are appreciated.
Your first mongoose.connect() argument lacks username / password combination:
mongoose.connect('mongodb://username:password#127.0.0.1:27017/exampleDB');
Try to connect db first before doing any action. Once it connected try to use inside your custom function. Below code will helps you to test local database
const express = require('express');
const app = express();
const port = 3000;
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/dbname', { useMongoClient: true });
mongoose.connection.on('connected', () => {
console.log('Connected to database ');
});
mongoose.connection.on('error', (err) => {
console.log('Database error: '+err);
});
// Start Server
app.listen(port, () => {
console.log('Server started on port '+port);
});
Check your cmd window to see console.
For connecting to a local mongodb, you can use this URI, replacing USER, PASSWORD are DB with your values :
mongodb://USER:PASSWORD#127.0.0.1/DB?authSource=admin
You don't need to provide the port 27017, because it's the default one for mongodb.
The trick here is to add with 'authSource=admin' for enabling the authentication.
Documentation :
https://docs.mongodb.com/manual/reference/connection-string/#examples

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