I'm trying Koa instead of express and I have a problem returning ctx.
Here is my code :
router.get("/user/:id", async (ctx, next) => {
mongodb.connect(url, { useNewUrlParser: true }, (err, db) => {
if (err)
throw ("error => " + err);
else {
var dbo = db.db("test");
dbo.collection("users")
.find({})
.toArray((err, res) => {
if (err)
throw ("error => " + err);
db.close();
console.log(res);
ctx.body = {
"message": "GOT IT"
}
})
}
});
});
The problem is that ctx is unknown in the callback.
Any idea on how I can put it into the callback?
btw res is filled properly.
Thanks for help!
Maybe the problem with the callback has to do that you first have to wait for the
dbo.collection("users").find({})
And the do
toArray()
I use the koa-mongo library.
This library inject mongo into the context.
Open and close mongodb connection is not needed.
server.js
import Koa from 'koa'
import Mongo from 'koa-mongo'
const app = new Koa()
app.use(new Mongo(dbConfig))
In the router
let db = ctx.mongo
const result = await db.collection("users").find({})
if (!result) {
return []
}
return result.toArray()
Related
I got the error when I trying to connect node to the database. I used the async function and try to apply the methods in other similar questions but still got it wrong. Here is my code:
const { MongoClient } = require('mongodb')
const url = "mongodb://localhost:27017"
const client = new MongoClient(url);
async function main(){
const dbName = 'my-react-admin'
try {
await client.connect();
console.log('Connect to database!')
const db = client.db(dbName);
db.collection('users').find({}).toArray((err, data) => {
if (err) throw err
console.log(data)
})
} catch (e) {
console.error(e);
} finally {
await client.close();
}
}
main().catch(console.error);
Thank you!
I found the answer, you just have to put client.close(); to
((err, data) => { if (err) throw err console.log(data) })
just like ((err, data) => {client.close();}).
it'll work.
I start to develop a simple web application with NodeJS. and when I try to get a list record from SQL Server to show on the list page but somehow it's not working.
Here is the code :
const express = require("express");
const bodyParser = require("body-parser");
const sql = require("mssql");
const DBUtils = require("./DBUtils");
const app = express();
app.get("/all", (req, res, next) => {
let mypromise = new Promise((reso, rej) => {
let nameList = DBUtils.getNameList(sql);
if (nameList !== null || typeof nameList !== "undefined") {
reso(nameList);
} else {
rej("Error");
}
})
.then((result) => {
res.send(result);
})
.catch((err) => {
console.log(err);
});
});
app.get("/", (req, res, next) => {
console.log("the / route");
res.send("<h1>Hello to NodeJS</h1>");
});
app.listen(5003);
My DBUtils
const config = {
user: "sa",
password: "123",
server: "DESKTOP-7KGJI7L", // You can use 'localhost\\instance' to connect to named instance
database: "java",
options: {
encrypt: false,
},
};
const getNameList = (sql) => {
let nameList = "";
let errorString = "";
// Create connection
sql.connect(config, function (err) {
// Err
if (err) {
console.log(err);
}
// Create Request object
let sqlRequest = new sql.Request();
// QueryString
let queryString = `select * from NAME`;
// Run the query
sqlRequest.query(queryString, (err, data) => {
if (err) console.log(err);
//console.log(data); //data.recordset(array)[index].name
data.recordset.forEach((el) => {
nameList += `<li>${el.name}</li>`;
});
return nameList;
});
});
};
exports.getNameList = getNameList;
I pretty sure something wrong in Promise line but don't know how to fix it. Any suggest?
I think you are a newbie in Nodejs You made a common mistake. You did not use promise pattern correctly. Also, no need to pass next callback unless required.
Change getNameList as below :
const getNameList = (sql) => {
let nameList = "";
let errorString = "";
// Create connection
return new Promise (function(resolve,reject) {
sql.connect(config, function (err) {
// Err
if (err) {
console.log(err);
reject(err)
}
// Create Request object
let sqlRequest = new sql.Request();
// QueryString
let queryString = `select * from NAME`;
// Run the query
sqlRequest.query(queryString, (err, data) => {
if (err) {console.log(err)
reject(err)
}
//console.log(data); //data.recordset(array)[index].name
data.recordset.forEach((el) => {
nameList += `<li>${el.name}</li>`;
});
resolve(nameList);
});
});
})
};
Change app.get("/all") as below:
app.get("/all", (req, res) => {
DBUtils.getNameList(sql).then(function(list) {
res.status(200).send(list)
}).catch(function(err) { //handle error here
res.status(500)
})
})
Moreover, learn how to use promises and async-await.
Use appropriate body-parser as per requirement ie json, text etc.
Learn how and when to use next
I was recently using a function to upload files to a mongodb database successfully. However after moving those functions into a file (to clean up) and exporting that file then requiring it in my route, the database now creates documents with only null values like so:
_id:ObjectId("xxxxxxxxxxxxxxx")
name:null,
value:null,
image:null,
desc:null
I don't know what might be causing this, I am logging the argument object that i'm trying to insert from inside the function 'insertProducts' and the item.name is not null. Sorry I'm new to mongodb :/
maybe someone can point me in the right direction?
CRUD.js
const mongodb = require('mongodb');
const MongoClient = mongodb.MongoClient;
const removeProducts = function(req,res){
MongoClient.connect('mongodb://localhost', (err, client) => {
if (err) {
throw err;
}
let db = client.db('account-app');
let products = db.collection('products');
let users = db.collection('users');
try{
products.remove({ _id: req.body.id }, function(err) {
if (!err) {
console.log('removed item')
}
});
}
catch(err){
console.log('Error while inserting', err)
}
client.close()
res.redirect('/addItems')
})
}
const insertProducts = function(item,res){
console.log("item name",item.name)
MongoClient.connect('mongodb://localhost', (err, client) => {
if (err) {
throw err;
}
let db = client.db('account-app');
let products = db.collection('products');
try{
products.insertOne(item)
console.log('item inserted')
}
catch(err){
console.log('Error while inserting', err)
}
client.close()
res.redirect('/admin/addItems')
})
}
module.exports={removeProducts: removeProducts, insertProducts: insertProducts}
my admin route that requires the crud functions
const crudOps = require('../utils/admin/CRUD') //require CRUD functions
// Adding new items
// --------------------------------------------------
router.post('/addNewItems', (req, res, next) => {
console.log(req.body.name)
let item = {
name:req.body.name,
file: binary(req.files.image.data),
value: req.body.value,
desc: req.body.desc
}
crudOps.insertProducts(item, res)
});
That connection URL looks wrong. Generally, it has the format:
mongodb://localhost:27017/mydatabase
Try replacing the connection string with the appropriate one for your database and see if that works. Also, the docs normally have insertOne statements like this so maybe that is the issue?
products.insertOne(item, function(err, r) {
console.log('item inserted')
res.redirect('/admin/addItems')
db.close();
});
I am trying to write an api that queries a mssql database. however my response from the api is always Promise { undefined }
app.get('/api/:year/:month', (req, res) => {
var data = getData(req.params.month, req.params.year);
console.log(data);
res.send(data);
});
async function getData(m, y) {
var query = "SELECT ...";
sql.connect(Config, (err) => {
if (err) {
console.log("Error while connecting to database :- " + err);
} else {
var request = new sql.Request();
request.query(query, function (err, rs) {
if (err) {
console.log("Error while querying database :- " + err);
} else {
return rs.recordset;
}
sql.close();
})
}
})
I'm assuming I need to await the result somehow as if I log the response inside the data function it is populated, however I can't seem to get anything to work.
You are creating it a callback style function but not really taking the value. You need to convert it to promise based like this and use async/await
app.get("/api/:year/:month", async (req, res) => {
const data = await getData(req.params.month, req.params.year);
console.log(data);
res.send(data);
});
async function getData(m, y) {
const query = "SELECT ...";
await sql.connect(Config);
const request = new sql.Request();
const rs = await request.query(query);
return rs.recordset;
}
I'm new to Node.js and am trying to pass some data from my DB model back to the router but I'm unable to find a solution. I have the following route file that makes a call to model:
Route file:
var express = require('express');
var router = express.Router();
var db = require('../db');
var customers = require('../models/customers');
db.connect(function(err) {
if (err) {
console.log('Unable to connect to MySQL.')
process.exit(1)
}
});
router.post('/', function(req, res) {
customers.checkPassword(req.body.cust_id, req.body.password);
res.sendStatus(200);
});
Model file:
var db = require('../db.js');
module.exports.checkPassword = function(cust_id, password) {
var sql = "SELECT Password FROM Shop.customers WHERE ID =" + cust_id;
db.get().query(sql, function (err, res, fields) {
result = res[0].Password;
if (err) throw err
});
};
My question is: how could I pass the queried result Password back to my Route file so that I can do this:
console.log('Password is', result);
I appreciate any help on this.
I'd use a promise
Model file
module.exports.checkPassword = function(cust_id, password) {
return new Promise(function(resolve, reject) {
const sql = "SELECT Password FROM Shop.customers WHERE ID =" + cust_id;
db.get().query(sql, function (err, res, fields) {
if (err) return reject(err)
result = res[0].Password;
return resolve(result);
});
});
};
Route file
var express = require('express');
var router = express.Router();
var db = require('../db');
var customers = require('../models/customers');
db.connect(function(err) {
if (err) {
console.log('Unable to connect to MySQL.')
process.exit(1)
}
});
router.post('/', function(req, res) {
customers.checkPassword(req.body.cust_id, req.body.password)
.then((result) => {
// DO: something with result
res.status(200).send();
})
.catch(console.log); // TODO: Handle errors
});
With async/await
router.post('/', async function(req, res) {
try {
const result = await customers.checkPassword(req.body.cust_id, req.body.password)
// DO: something with the result
} catch (e) {
console.log(e); // TODO: handle errors
} finally {
res.status(200).send();
}
});
I assume console.log('Password is', result); is just for test prupose, obviously you should never log a password! Also I suggest to move the callbabck of the routes do a different module, to improve code redability.
You might also find useful promise-module module on npm, basically a promise wrapper around mysql.
You can delegate the credential control to another function in your DB file where you can decide on what kind of data you want to return on success and failure to find such data. Then you can access it from where you are calling it.