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Confusing error message using updateOne() function on a mongodb collection

To summarize, I have a mongodb database with a 'groupcollection' in it. One of the attributes is called 'deleted' and it has values either true or false. I want to update the value of 'deleted' for a specific document using 'groupname' as the query attribute. However, when I try the code below I receive the error "TypeError: collection.updateOne is not a function"
router.post('/deletegroup', function(req, res) {
var db = req.db;
var collection = db.get('groupcollection');
var filter = {"groupname" : req.body.groupname};
var updates = { $set: {"deleted" : true} };
collection.updateOne(filter, updates, function(err) {
if (err) {
// If it failed, return error
res.send("There was a problem deleting the group from the database.");
}
else {
// And forward to success page
res.redirect("grouplist");
}
});
});
I've read the documentation on updateOne() for Node.js from mongoDB and I can't seem to figure out the reason for the error. Also, I am still very new to javascript/nodejs/mongo so I would greatly appreciate more informative answers!

The solution I came up with was using unique IDs for each group and instead of using updateOne() just using update() and having the unique ID as the query to make sure that I don't modify groups with the same name

How to insert new MySQL JSON TYPES object from the browser in NODE.JS

I had this question about sql, json, and nodeJS. Is there a way I can insert something like this through node.js (Here's the link from oracle official website where I was referring to: enter link description here)
INSERT INTO t1 VALUES('{"key1": "value1", "key2": "value2"}');
I'm trying to come up with a better data structure for my project. I've been using simple sql queries just like the ones from W3SCHOOL, but the more I keep working on my project, the more I realize that using JSON DATA TYPE would be more appropriate.
And here's how I was trying to insert an object from my server.js file, but without success!!!
app.get('/demo/add/', (req, res) => {
const { content, author, ID} = req.query;
const sql = `insert into demo values({'${content}':'content', '${author}':'author', '${ID}':3})`
con.query(sql, (err, results) =>{
if(err){
return res.send(err)
} else{
return res.send('Successfully added a new content!!')
}
})
});
Previously, I had been using this method: http://localhost:4000/demo/add?key1=value&key2=value2... for simple query, but for now, I'm kind of stuck!!
Thank you in advance

I used json_extract() method to retrieve data from sql tables, and that's pretty much what my struggle was about.

Mongodb does not save a document

I am trying to store some data from an HTML formulary. I send the data using the HTTP POST method and I received them using Express framework in Node.js. The data arrives and it seems to work, but when I try to store them into MongoDB using Mongoose, the database is created but no data is stored when I execute DB.sis_dictionary.find()
I've tried to build different types of schemas and models, but none seems to work. And I get no error from Node.js, it seems to be working, but the MongoDB database does not store anything.
const Mongoose = require('mongoose');
Mongoose.connect('mongodb://localhost:27017/sis_dictionary', {useNewUrlParser: true});
const Schema = Mongoose.Schema;
const wordSchema = new Schema({
word: String
})
const Word = Mongoose.model('Word', wordSchema);
app.post('/saveWord', (req, res) => {
var word = new Word({word: String(req.body)});
word.save(function(err){
if(err) {
return console.error(err);
} else {
console.log("STATUS: WORKING");
}
})
console.log(req.body);
})
server.listen(3000);
console.log("SERVER STARTUP SUCCESS");
In the console, I get the message: "STATUS: WORKING".

sis_ditionary is your DB name and Words should be your collection name. As mongoose automatically creates a plural name for collection from a model if model name not specified when creating from a schema
db.collection.find() is a command to find a collection data when using mongo-shell. Run below command to get data:
use sis_dictionary
db.Words.find()
To beautify result use pretty method
db.Words.find().pretty()
First command will select DB and second command list collection data.
So when you execute db.sis_dictionary.find() it won't work because sis_dictinary is your DB name.
Nodejs way with 'mongoose'
//Model.find({});
Word.find({});
Also, check this line var word = new Word({word: String(req.body)});
What does req.body have? If req.body is {word:"example word"} then you directly pass req.body to modal constructor ie new Word(req.body);

According to your database URL, mongodb://localhost:27017/sis_dictionary, sis_dictionary is the database name.
And according to your mongoose model, Word is your collection name.
When you save a document, it saves under a collection. So you have to make a query under the collections.
So when you try to get data using DB.sis_dictionary.find(), definitely it won't work.
Your query should be like db.collection.find()
Use the following query,
use sis_dictionary
db.words.find()
// for better view
db.words.find().pretty()
For more please check the documentation.

Thank you everybody. You were all right, it was a problem related to my collections names. db.words.find().pretty() worked perfectly!The problem is solved.

How to fix deleteOne() function of a mongoose model when it does not delete by req.params.id?

Firstly to be mentioned, I'm absolutely new to Node.Js and MongoDB.
I'm coding a back end API with Node.Js and MongoDB which will deal with GET, POST, DELETE requests from the front end, quite simple stuff.
I'm stuck while working with DELETE functionality.
Here is my posts.service.ts file contains this deletePost() function which sends the postId to the back end app.js file.
`
deletePost(postId: string) {
this.http.delete('http://localhost:3000/api/posts/' + postId)
.subscribe(() => {
console.log(postId);
console.log('Deleted');
});
}
`
I have added this console.log(postId) to check whether it is actually containing the actual postId and found that it does. I have also matched it with the real Id in MongoDB by checking through mongo shell.
Here is the delete() function in the back end app.js file that should do the actual task.
`
app.delete("/api/posts/:id", (req, res, next) => {
Post.deleteOne({ _id: req.params.id }).then(result => {
console.log(result);
res.status(200).json({message: "Post deleted"});
});
});
`
The console.log(result) line should print some result in the terminal, but it does not, so does not it delete the collection in the DB.
I`m running this on an Ubuntu 16.04 LTS pc.
Some clue would mean great help. Thank you very much for your kind effort.

deleteOne doesn't return the deleted document. It always deletes the first matching document and return the number of documents deleted with the boolean value.
From the mongodb docs deleteOne:
Returns:
A document containing: A boolean acknowledged as true if the operation ran with write concern or false if write concern was
disabled
deletedCount containing the number of deleted documents
From the mongoose docs
Deletes the first document that matches conditions from the
collection. Behaves like remove(), but deletes at most one document
regardless of the single option.

I was facing exactly the same, i solved returning the deleteOne promise object and then using the .then property of the promise.
Something like this:
Model.js
...
bicicleSchema.statics.deleteById= function(id, cb){
return this.deleteOne({code: id}, cb);
};
...
module.exports = mongoose.model('Bicicle', bicicleSchema);
Service.js
var Bicicle = require('../../../model/bicicle');
...
const id = req.params.id;
Bicicle.deleteById(id).then(()=>{
//your code
});
...

Using mysql node.js driver to get an entire database as JSON

I'm working on creating a JavaScript file to get a JSON dump of an entire MySQL database, running on server side. I found and am using the MySQL driver for node.js (https://www.npmjs.com/package/mysql) for queries, it's been straight forward enough to start. My issue is that I need to call multiple queries and get the results from all of them to put into a single JSON file and I can't quite get that to work. I'm entirely new to JavaScript (basically never touched it before now) so it's probably a relatively simple solution that I'm just missing.
Currently I do a query of 'SHOW TABLES' to get a list of all the tables (this can change so I can't just assume a constant list). I then just want to basically loop through the list and call 'SELECT * from table_name' for each table, combining the results as I go to get one big JSON. Unfortunately I haven't figured out how to get the code to finish all the queries before trying to combine them, thus retuning 'undefined' for all the results. Here is what I currently have:
var mysql = require('mysql');
var fs = require('fs');
var connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'pass',
database: 'test_data'
});
connection.connect();
connection.query('SHOW TABLES;', function(err, results, fields)
{
if(err) throw err;
var name = fields[0].name;
var database_json = get_table(results[0][name]);
for (i = 1; i < results.length; i++)
{
var table_name = results[i][name];
var table_json = get_table(table_name);
database_json = database_table_json.concat(table_json);
}
fs.writeFile('test_data.json', JSON.stringify(database_json), function (err)
{
if (err) throw err;
});
connection.end();
});
function get_table(table_name)
{
connection.query('select * from ' + table_name + ';', function(err, results, fields) {
if(err) throw err;
return results;
});
}
This gets the table list and goes through all of it with no issue, and the information returned by the second query is correct if I just do a console.log(results) inside the query, but the for loop just keeps going before any query is completed and thus 'table_json' just ends up being 'undefined'. I really think this must be an easy solution (probably something with callbacks which I don't quite understand fully yet) but I keep stumbling.
Thanks for the help.

I'm guessing that this is for some sort of maintenance type function and not a piece that you need for your application. You're probably safe to do this asynchronously. This module is available here: https://github.com/caolan/async
You can also use Q promises, available here: https://github.com/kriskowal/q
This answer: describes both approaches pretty well: Simplest way to wait some asynchronous tasks complete, in Javascript?