This is a piece of code from my main js file which i'm using to call a function in another js file(js.js)
var fields = "workaholic alcoholic insomniac";
var valid = require("./js");
Hacker.find({name: "arun"}, fields)//, function(err, hackers) {
.then(valid.myfun)
.catch(err => console.log(err,fields));
This is the js.js file which i'm referencing in the main js file
exports.myfun = function(hackers) {
console.log(hackers);
console.log(hackers.workaholic);
var workaholic = hackers.workaholic;
var alcoholic = hackers.alcoholic;
var insomniac = hackers.insomniac;
console.log(workaholic);
console.log(alcoholic);
console.log(insomniac);
show(workaholic,alcoholic,insomniac);
}
function show(a,b,c) {
console.log("Am I workaholic: "+a);
console.log("Am I alcoholic: "+b);
console.log("Am I insomniac: "+c);
}
When i execute the main js file, I notice that I'm getting my query response in an array.
C:\Users\Balajee\Desktop\project\Ultro>node hack
[ { fun: {},
workaholic: 'Yes',
alcoholic: 'No',
insomniac: 'Yes',
_id: 5706541ba3fe824c2f017680 } ]
When i try to set the value of these fields to variables, I'm getting "undefined"
_id: 5706541ba3fe824c2f017680 } ]
undefined
undefined
undefined
undefined
Am I workaholic: undefined
Am I alcoholic: undefined
Am I insomniac: undefined
So, how do i fetch the value of the field which is returned by the mongoose in an array? is it possible to return the query without array?
Use findOne() instead of find(). This returns a JSON object rather that array of JSON objects.
You can use findOne instead of find. findOne will return a single object that matches your query, instead of an array.
Hacker.findOne({name: "arun"}, fields)
I think you should do:
exports.myfun = function(err, hackers) {
// ...
}
because the callback takes err as first param
Related
Hi I tried to update the element at a particular index in an array but I'm not able to update it. It is updating the entire array. Not able to figure out how to update any particular index. Also tried
{$set:{"Data.1:req.body}}
this is updating at 1st index but I don't want to hardcode the index value. It should take from frontend. Let say I have a schema in which I have Data who's type is array and default value is as shown below or anything in the same format.
Data: {
type: Array,
Default: ["0","1","0"]
}
Whenever I'll create a user then Data field will contain these default values, But now I want to update the value at any index (coming from frontend) of Data array of any user created.
I tried findByIdAndUpdate method but I don't know what to pass in set property. If I'm passing this {$set: req.body} and In postman I'm giving any value of Data then obviously it is updating Data array but I want to update value at any index which I'm passing from frontend, let say the index I'm passing is 2 then it should update the value of array at index 2, similarly I can pass any index from frontend how should I do that. What changes I have to make in {$set : } Thanks in advance.
Waiting for any help or suggestions. Thanks
It appears that you can solve this in backend logic if you are passing the index from the frontend.
You can dynamically specify the index, based on the input from the frontend, before you send a query.
const updateUserData = async (req, res) => {
const { index, user_id, new_value } = req.body;
try {
const update = {};
update[`Data.${index}`] = new_value;
const data = await Users.updateOne(
{ _id: user_id },
{ $set: update }
);
return res.status(200).json({ success: true });
} catch (error) {
return res.status(500).json({ success: false });
}
};
Suppose a schema
const sch = new mongoose.Schema({
obj: {
subObj: String;
}
});
Then I observe that an non-existing or empty property of a document gives me isEmpty == false.
import { isEmpty } from 'lodash';
// Insert an empty document (i.e. no `obj` property)
Sch.create([{}]);
Sch.findOne({}. (err, doc) => {
// Below gives `{}`
console.log(doc.obj);
// Below gives `false`
console.log(`isEmpty == ${isEmpty(doc.obj)`);
});
I suspect that it is because the document contains obj as its key, i.e. Object.keys(doc).includes('obj') == true or Object.getOwnPropertyNames(doc).includes('obj') == true. But I have no idea to deal with it.
What is a proper way to check emptiness of a mongoose document property ?
Update:
The reason that you are getting that is:
console.log(Object.keys(doc.obj), Object.keys({}));
when running the command above I get: [ '$init', 'subObj' ] [] which means that your Object is not really empty, lodash is probably checking those attributes
You could use something like this:
Sch.findOne({}, (err, doc) => {
if (JSON.stringify(doc.obj) === JSON.stringify({}) ) {
// logic goes here
}
});
I found the solution in mongoose itself. The below does what I tried with lodash
doc.$isEmpty('obj')
Reference
Document.prototype.$isEmpty()
I've a node.js api in which user sends the required fields as an array to be fetched from the mongodb database. I need to find the data of that fields using Find query. I've written forEach statement to loop through that array and got the array elements. But when I try to get the results by inserting the array elements in the query, it doesn't giving the required results. Could any one please help me in resolving the issue by seeing the code below?
templateLevelGraphData: async function(tid,payload){
let err, templateData, respData = [], test, currentValue;
[err,templateData] = await to(Template.findById(tid));
var templateId = templateData.templateId;
payload.variables.forEach(async data=>{
console.log(data); //data has the array elements like variables=["humidity"]
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({},{data:1}).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue);
});
return "success";
}
The expected output is,
[ { humidity: 36 } ]
But I'm getting only _id like,
[ { _id: 5dce3a2df89ab63ee4d95495 } ]
I think data is not applying in the query. But I'm printing the data in the console where it's giving the correct results by displaying the array elements like, humidity. What I need to do to make it work?
When you are passing {data: 1} you are passing an array where is expecting name of column.
You have to create an object where the keys are going to be the elements of the array and set them to 1.
const projection = data.reduce((a,b) => (a[b]=1, a), {});
[...] .find({}, projection) [...]
Actually I got the solution.
for(let i=0;i<payload.variables.length;i++){
var test = '{"'+ payload.variables[i] +'":1,"_id":0}';
var query = JSON.parse(test);
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({"deviceId":deviceId},query).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue); //It's giving the solution
}
I'm shortlisting the 2 elements from one schema and want to update in another schema. for that i used slice method to shortlist first 2 elements from an array. but am Getting
CoreMongooseArray ['element1','element2']
instead of ["element1", "element2"]
How do i remove "CoreMongooseArray" ?
connection.connectedusers.find({}, async (err, docs) => {
if(err) throw err;
var users = docs[0].connectArray;
if (docs[0] != null && users.length >= 2) {
var shortListed = users.slice(0, 2);
try {
await connection.chatschema.updateMany({}, { $push: { usersConnected: [shortListed] } }, { upsert: true });
} catch (err) {
res.status(201).json(err);
}
}
You need to add lean() to your query.
From the docs:
Documents returned from queries with the lean option enabled are plain javascript objects, not Mongoose Documents. They have no save method, getters/setters, virtuals, or other Mongoose features.
If you already got the mongoose array and like to convert to simple js array
const jsArray = mongooseArray.toObject();
https://mongoosejs.com/docs/api/array.html#mongoosearray_MongooseArray-toObject
For some reason .toObject() didn't work for me. lean() option works, but it's not suitable when you already have an object with mongoose array in it. So in case if you already have mongoose array and you want just to convert it to plain js array you can use following code:
function mongooseArrayToArray(mongooseArray) {
const array = [];
for (let i = 0; i < mongooseArray.length; i += 1) {
array.push(mongooseArray[0]);
}
return array;
};
usage:
const array = mongooseArrayToArray(mongooseArray);
If you just want to convert the CoreMongooseArray to a normal array without changing anything else:
const jsArray = [...mongooseArray];
i have small problem i have this code:
Messages.findOne({id_user: to}, function (err, toUser) {
//dopisujemy wiadomość w tablicy użytkownika
var messArray = toUser.messagesArray;
//przeszukujemy tablice z wiadomościami aby znaleźć odpowiedniego użytkownika
for(var i=0;i<messArray.length; ++i) {
if(messArray[i].id_converser = who) {
// console.log(messArray[i]);
toUser.messagesArray[i].messages.push({id_converser: who,message: message,date: Date()});
toUser.save(function (err) {
if(err) console.log(err);
console.log('Wiadomość dodana');
})
return;
}
}
}) //end zapisujemy wiadomość w miejscu przeznaczenia
and everything seems fine, in console i have message "wiadomosc dodana", but when i check it in database i not see this added data, why.
Thanks for reply.
In order to push to the array in the actual database you need to use $push or something like $addToSet operator
When you modify any deep property or array property of an object in JavaScript you need to use isModified method in order to tell Mongoose that a property of the object is modified and update it in the database.
http://mongoosejs.com/docs/api.html#document_Document-isModified
So you need to execute it after the push function like that:
toUser.isModified('messagesArray')