I am retrieving a document from MongoDB using find() in Node.js, while printing the result I am not getting the retrieved values. Here my code..
db.collection("Product").find({'entry_id':entryID},function(err, result) {
console.log("Output:",result);
You could just about place money on entry_id is an ObjectId value and what you are passing as a variable is actually just a string.
But the other obvious thing is that you are using .find() in the wrong way. The "result" returned is a
"cursor". If you want something that looks like a whole result set, then use .toArray() or other similar method of conversion:
var ObjectID = require('mongodb').ObjectID;
db.collection("Product").find({
'entry_id': new ObjectID(entryID)
}).toArray(function(err, result) {
console.log("Output:",result);
});
Related
I am attempting a CRUD app with MEAN stack. I am using mongoose in Express to call to the MongoDB. I am using the FindOne function with a specified parameter, and it's always returning the same (incorrect) document.
I know I am connected to the correct database, since I get a document back from that collection, but it's always the same document, no matter what I pass as the parameter.
module.exports = mongoose.model('Player', playersSchema, 'players'); //in player.js
const Player = require('./model/players');
app.get('/api/player/:id', (req, res) =>{
Player.findOne({id: req.params.playerId},
function(err, player) {
if(err) {
res.json(err);
}
else {
res.json(player);
}
});
});
I have 3 separate "players", with three distinct "playerID" fields (38187361, 35167321, 95821442). I can use Postman to GET the following URL, for example:
http://localhost:3000/api/player/anythingyouWantInHere
and it will return 38187361, the first document. I've been over this website, many tutorials, and the Mongoose documentation and I can't see what I'm doing wrong..
I'd like to eventually find by playerId OR username OR email, but one hurdle at a time...
From the mongoose documentation of findOne, if you pass Id a null or an empty value, it will query db.players.findOne({}) internally which will return first document of the collection everytime you fetch. So make sure you are passing non-empty id here.
Note: conditions is optional, and if conditions is null or undefined,
mongoose will send an empty findOne command to MongoDB, which will
return an arbitrary document. If you're querying by _id, use
findById() instead.
Your route is '/api/player/:id', so the key on the req.params object will be 'id' not 'playerId'.
I don't know what/where/if you're populating the playerId param, but if you update your query to call req.params.id it should actually change the document based on the path as you seem to be wanting to do.
I had the same problem, and it was that the name of column's table was different from the model I had created.
In my model the name of the wrong column was "role" and in my table it was "rol".
I have a query which looks as such:
collection.find({}, {_id: 0}).toArray((err, result) => {
io.sockets.connected[clients[client.length-1]].emit('update chart state', result);
});
My websocket is sending the data correctly to the client however the _id field is still present in the array of objects that I receive. Could someone point out to me what I am missing here?
Thank you
The find function takes only one parameter - the query. The returned value is a Cursor, which contains a project function. You can, therefore, use something like this:
collection.find({}).project({_id: 0}).toArray ...
Database : Mongo 3.4+
NodeJS:v6.9.4
OS: Centos 7+
In mongo shell, following command return result,
db.processticket.find({"parentProcessID": "5978ab9f82c56ec868d0d002"})
however, following code find/findOne returns empty result
app.models.processticket.findOne({
where: {"parentProcessID": "5978ab9f82c56ec868d0d002" }
}, function(err, result) {
You can use strictObjectIDCoercion flag in model definition file. Reference
Please wrap the value of parentProcessID in ObjectId function. Since mongo saves Id values as ObjectId in your where query you need to warp the value of your parentProcessID with ObjectId function. You can find ObjectID function in native mongodb module
const ObjectID = require('mongodb').ObjectID;
I'm currently working on a project with mongodb/mongoose, and every time I purposely query for something that does not exist in the DB, I am getting a response with an empty array. This is my code for using Express to set up an API and return the data found in the DB:
app.get('/api/:id', function(req, res) {
var id = req.params.id;
Job.find({jobID: id}, function (err, foundJob) {
if (err) {
console.log(err);
}
else {
res.json(foundJob);
}
});
});
However, every time I go to localhost:3000/api/67 (I have no object with jobID: 67 in the database yet), the console does not print the error. It gives me a JSON response with an empty array. Any ideas to why this is happening? The weird part is that when I change jobID: id to _id: id, it does give me an error. Why doesn't it do that for the jobID field?
EDIT: Just to clarify, the reason why I do not want this behavior is because my program will never print the error, even if a job in my DB doesn't exist with that specified jobID.
It does something different than you think it does.
Job.find({jobID: id}, ... )
What this really says is give me array with all the documents in collection "Job" that have field "jobID" equal to some value.
What if there is no such document? Well, then the array will be empty. Without any error, of course, what should be an error here? You asked for all documents (given some filter) and an array with all such documents was returned. It is just a coincidence that the size of the array is zero, because there are no such documents.
If you want to check whether there is no such document then check whether the array is empty.
I don't know why it is giving you error when you change JobID to _id; what error exactly is it?
If you are interested only in one document, then there is method findOne that returns only the first document (or null if no such documents exist) instead of an array.
About error when you try to find something by it's __id: It gives you a error because __id is not String, it's ObjectId. So you should search for document with that __id like this: _id: ObjectId(id)
About empty string: If you want to display some kind of different message you should check if db returned something or is it rather empty string that got returned. Something like this:
app.get('/api/:id', function(req, res) {
var id = req.params.id;
Job.find({jobID: id}, function (err, foundJob) {
if(foundJob){
res.json(foundJob);
}else{
res.json("nothing found");
}
if (err) {
console.log(err);
}
});
});
Edit: I didnt realize that you had check for error, I changed code.
Returning an empty string is normal behavior for mongoose. You should handle your response like this:
if (err) {
//handle error
} else if (foundJob) {
//work with your data
} else {
//nothing was found
}
The error you get with _id must be irrelevant and is probably due to an invalid query.
I'm trying a very simple CRUD API with the MEAN stack. I entered several documents into a mongolab sandbox db. I could do a GET on all documents and they would all be returned. Then I tested GET by ID:
router.route('/api/v1/resources/:resource_id')
// get the resource with that id (accessed at GET http://localhost:8080/api/resources/:resource_id)
.get(function(req, res) {
Resource.findById(req.params.resource_id, function(err, resources) {
if (err)
res.send(err);
res.json(resources);
});
});
And it simply wouldn't work. I kept getting null. But the document existed. I could see it when I would do a GET on all documents.
Then I got another document to return, finally.
The difference? The record that returned had an id in this format:
{
"_id": { "$oid":"1234567890abc"}
}
But records that did not return had this:
{
"_id": "1234567890abc"
}
Can Anyone explain this to me? I entered the data with Postman and I didn't do anything different between the entries.
What is $oid?
What creates the $oid?
Why does that nesting matter for mongoose's findById()?
Thanks!
$oid is from Strict MongoDB Extended JSON.
All your queries to MongoDB database that contains _id conditions should wrap _id in ObjectId function like the following:
db.resources.findOne({_id: ObjectId("507c35dd8fada716c89d0013")};
MongoLab provides UI for querying to MongoDB via JSON syntax. But you can't use ObjectId in JSON due specification restrictions.
So, MongoLab uses Strict MongoDB Extended JSON for alias ObjectId() -> $oid.
{"_id": {"$oid":"507c35dd8fada716c89d0013"})
Same $oid you see in the output because MongoLab UI uses JSON also.
Mongoose automatically converts a string _id to MongoDB query so you don't need doing it manually. The following queries are equivalent:
Resource.findById("507c35dd8fada716c89d0013");
Resource.findById(new mongoose.Types.ObjectId("507c35dd8fada716c89d0013"));