i'm been trying to display just a simple data from mongolab to nodejs and it displays nothing for some reason.
var express = require('express');
var router = express.Router();
var mongoose = require('mongoose');
mongoose.connect("mongodb://db-user:pass#ds049084.mongolab.com:49084/mydb");
mongoose.model('collection',{ name:String });
router.get('/', function(req, res, next) {
mongoose.model('collection').find({},function(err,docs){
res.send(docs);
});
});
I've already saved a name data in the document of the collection in mongolab, the only it shows when i run the debug script
debug=mynode:* npm start is []
does anybody know why is that? thank you.
Fixed it!, man..the problem is the way i named the collections at mongolab. I was missing the "s" at the end of collection. Once i deleted the collection and created another but this time the "s" at the end, then it worked.
e.g.
Naming a collection 'Car' will not work but naming it 'cars' will work somehow
I can't comment yet because of my rep...
But to elaborate.. The reason why you need the "s" at the end is because when you do:
mongoose.model('<the schema you want to map to in your db>',<yourschema>);
"Mongoose automatically looks for the plural version of your model name" in your db.. as it says in the Mongoose documentation.. hence if you type myDbSchema it would look for myDbSchemas (Note the "s") and so thats why in your mongolabs Db the schema would need the extra "s"... confused me for a bit to but I hope this can help someone! :) as this post did help me too.
FYI Mongoose documentation: Mongoose Models Doc
Related
I am trying to generate Mongoose compliant ObjectId's on a NextJs frontend. The thing is though, the minute you import mongoose to try use the good-ol' const ObjectId = mongoose.Types.ObjectId; then const _id = new ObjectId(); 'maneuver' it immediately throws a TypeError: t.versions.node is undefined error in my case (very hard to debug the first time.. I was optimist it would work maybe this time doing some refactoring a few months later... But the minute I tried like oil in water.).
import mongoose from 'mongoose';
// and
const mongoose = require('mongoose');
Give the same error.
Is there a better way to create it? Other systems rely on this being a valid Id i.e. not just the same alphaNumeric length.
Less of a performance hit than creating a NextJs API GET route that just returns my backend shenanigans as a simple string (a network request?).
P.S. Use TypeScript if that could mean anything.. Also using Vercel (which has also caused build problems in the past)
I was too stuck in looking for a NextJs solution in my searches when it is still Javascript and React at the end of the day. This thread had the answer:
npm i bson
then
import { ObjectID } from 'bson';
const id = new ObjectID();
Works perfectly in NextJs as well as my Mongo/Mongoose database.
I am new to Node JS technology. I have 3 basic doubts.
In my nodeJS application, I connected to mongodb using mongoose. But I did not mention any collection name. But data is getting saved when I sent data from Form as expected. I want to know that in which collection it will be stored by default. How to see the stored data.
how to mention specific collection name using mongoose if we want to save data in a particular collection.
3.Generally If we want to use any middleware in our app, we connect that
middleware using app.use() right? but in mongoose case, we do not add that
to app.use(). but still we can use the mongoose functionality.
could anyone please tell how it is possible.
Thanks a lot in advance.
How Mongoose interacts with MongoDB is described here.
It has this example:
var schema = new mongoose.Schema({ name: 'string', size: 'string' });
var Tank = mongoose.model('Tank', schema);
and mentions that
The first argument is the singular name of the collection your model is for. Mongoose automatically looks for the plural version of your model name. Thus, for the example above, the model Tank is for the tanks collection in the database.
model() takes a third argument where you can rename the collection:
var Tank = mongoose.model('Tank', schema, 'collectionname');
The collection gets made when model() is called.
app.use() is used for Express middleware. Mongoose isn't really that, which is why you're not using app.use() in this case.
This should probably be broken into multiple questions and you should probably show some code. That said, I'll take a crack at it.
Collection names are defined when you model your schema. So let's say you have:
const UserSchema = new Schema({
name: String
});
And then you later will tell mongoose to model it:
mongoose.model('User', UserSchema);
You'll have a collection called "users" in the database you're connecting to in your mongoose.connect() call.
Regarding middleware, Express middleware is specifically functions that you want to fire during the request/response cycle. You can still call code (e.g. mongoose) outside that cycle, and generally you'll connect to the database when the application starts and then read or save to it in either middleware or in your route handlers. For example, you might have a route like:
const User = mongoose.model('User');
app.get('/users', (req, res, next) => {
User.find({}, (err, users) => {
if (err) return next(err);
res.send(users);
});
});
In that case, you've got a route handler that calls mongoose through the User model previously defined.
I am having trouble with require executing my code twice. Working on a standard Express app I build Mongoose Schemas, each in it's own files and export them.
//user.js
const User = mongoose.model('User', userSchema)
module.exports = User
//In other files
const User = require('../models/User')
Now I use this in two places in my application and get an error saying that
Cannot overwrite `User` model once compiled.
So the code above is getting called twice as it is the only code right now creating a model. However I would expect Node to only execute it once since it is required in my code.
The really strange part is that checking out an earlier version from Git I get the same error and people working with me on this get the same error. So I have no more ideas where to look for solutions.
Found the solution now.
Turns out I required the module once as models/user and once as model/User which in the cache of require creates two separate modules.
There have been many discussion about this:
one issue
another issue
old PR
It seems that this is due to Windows resolving paths case insensitive while other systems resolve paths case sensitive and node therefore doing it sensitive.
And a new module of'cause gets executed. Simply requiring is both times spelled in lowercase solved the issue.
I think the problem is in "const" that you use to declare the variable "User".
Try to use "var" instead of .
//user.js
var User = mongoose.model('User', userSchema)
module.exports = User
//In other files
var User = require('../models/User')
P/S: This is link that clarify more about "const" and "var":
Const in javascript? When to use it and is it necessary
Hope it helpful for you !
I am writing an application using yeoman angular-fullstack,
I defined some entities that I would like to access from other entities controller.
For example I have in my server->api->Mall I have the following code:
var MallSchema = new Schema({
...
});
module.exports = mongoose.model('Mall', MallSchema);
in other Business controller I would like to search for Mall by _id, using mongoose, But I can not import MallSchema trying to do the following:
mall = mongoose.models("MallSchema").find({_id: "some_mall_id"})
business.mallType = mall.type
business.update();
or nesting Schema's
var MallSchema = new Schema({
business : Business;
});
I really tried in lot of ways, ending up with frustration, googling this yields lots of answers, none have works and few just seems too complicated like this one, I newbie to node.js so I mast been missing somthing simple. any help would be nice for the entire community.
it seems simple but somehow missed from documentation
this seems to work for me now
var business = require('../business/business.model')();
var user = require('../user/user.model')()
Hope it helps.
My modules get a mongoose instance injected but now they all use the database that was set on the last mongoose.
For example my main module creates a lot of modules and then calls init on them.
var mongoose = require('mongoose');
//...
mongoose.connect(connString);//specific to finance
var finance = require('finance').init({db:mongoose});
Before I injected the mongoose instance the finance module required mongoose by itself and since it's in the node_modules it gets it's own mongoose. Now; no matter how many main modules I make and how many times I call require it'll always get the instance it got the first time.
Therefor all modules created will be connected to whatever is set by the last connect.
It is possible to use createConnection but still not sure how to inject mongoose, I tried:
var mongoose = require('mongoose');
//...
var c = mongoose.createConnection(connString);//specific to finance
mongoose.connection=c;
var finance = require('finance').init({db:mongoose});
Now I get an error like Cannot overwritefinancemodel once compiled.
Somehow it's very hard to get another instance of mongoose in the same module. This is funny because according to mongoose you should be able to use different connections for different models but since you need a mongoose instance to define a model then how do you inject it? Require keeps returning the same instance over and over again.
Tried the following but both didn't work.
console.log('deleting mongoose cache:',require.cache.mongoose=undefined);
//or this one
console.log('deleting mongoose cache:',delete require.cache.mongoose);
So the question is: how do I inject mongoose in my modules that have models that require a unique database? If main sets up the mongoose instance and connection to inject into the model then how do I prevent it from creating the same one over and over again?
If it's possible to create unique connections with createConnection then what do I inject into the modules? With this connection I can't create models, need a mongoose instance for that. If each model needs to invoke require to get it then mongoose is un injectable.
So mongoose uses a singleton pattern. When you do require("mongoose") you are getting the same instance of a constructor each time as seen at the bottom of mongoose/lib/index.js (source code link here). var mongoose = module.exports = exports = new Mongoose;
To get unique instances, use this pattern:
var singleton = require("mongoose")
var unique = new singleton.constructor();
//now use "unique" just as you would "mongoose"