I'm trying to get a list of all "Task" documents from my mongoDB in a reverse order, so latest added "Tasks" are first in the list.
Is there a smart way of doing that?
allTasks(){
return Task.find(function (err, allTasks) {
if (err) return console.error(err);
return allTasks;
})
}
UPDATE
Following code solves the problem:
allTasks(){
return Task.find().sort({created_at:-1}).exec(function (err, allTasks) {
if (err) return console.error(err);
con
return allTasks;})
}
Related
I am having issues storing a value in mongodb to a variable to use within my webpage.
When the user fills out a form on my website, I am trying to figure out what the arrivalTrailer was when the user filled out the arrival form.
So far I have
function previousLoad(loadNumber, callback){
CheckCall.find({loadNumber: loadNumber}).sort({date: 'desc'}).limit(1), function(err, arrival){
if (err){
callback(err, null);
}
else {
callback(null, arrival[0]);
}
}};
previousLoad(loadNumber, function(err, arrival){
if (err){
console.log(err);
}
else{
arrivalTrailer = arrival;
console.log(arrival);
}
});
console.log(previousLoad.arrival);
console.log(arrivalTrailer);
Both output as undefined when I try to console.log the variables.
Thank you :D
Try this :
async function previousLoad(loadNumber) {
try {
let resp = await CheckCall.find({ loadNumber: loadNumber }).sort({ date: -1 }).limit(1)
return resp[0]
} catch (error) {
console.log('error ::', error)
throw new Error (error)
}
}
/** You can return response from previousLoad but to test it, Call it from here */
previousLoad(loadNumber).then(resp => { console.log('successfully found ::', resp)}).catch(err => { console.log('Error in DB Op ::', err)});
I've a mongo database with 3 collections for 3 different kind of users as User,Partner,Admin. Whenever a new user of any type signup I'm searching all three collections to check if username and email exist already. I'm trying to achieve this by calling a function as:
function checkAttribute(attr,val,callback){
User.find({attr: val},function(err,user){
if(err){
console.log(err);
}else{
if(user.length === 0){
Partner.find({attr: val},function(err,partner){
if(err){
console.log(err);
}else{
if(partner.length === 0){
Admin.find({attr: val},function(err,admin){
if(err){
console.log(err);
}else{
if(admin.length === 0){
return callback(null,true);
}else{
return callback(null,false);
}
}
});
}else{
return callback(null,false);
}
}
});
}else{
return callback(null,false);
}
}
});
};
Calling function line:
checkAttribute("username",newUser.username,function(error,response){
.......
});
But this is not working as it returns true always even when users with passed username/email exists already. I am unable to find the problem. Any one knows why this is happening?
Thanks in advance.
Since you are passing in the attribute as a variable in the function parameters, the query document
{ attr: val } is an object with the key "attr", not the dynamic attribute you pass in.
To fix this, you need to use computed property names in your query object as
{ [attr]: val }
Also, the function can use async/await pattern to be more readable and for the purpose of finding if a document exist findOne does the job so
well as it returns a document if it exists and null otherwise.
So your function can be refactored as
async function checkAttribute(attr, val, callback) {
try {
const query = { [attr]: val }
const user = await User.findOne(query).exec()
const partner = await Partner.findOne(query).exec()
const admin = await Admin.findOne(query).exec()
const found = (user || partner || admin) ? true: false
return callback(null, found)
} catch (err) {
console.error(err)
return callback(err, null)
}
};
attr: in your queries will search for a db field called attr. If you want to use the function parameter attr, use [attr]: as the key.
Example:
attr = 'username'
User.find({ [attr]: val }, function (err, user) {
if (err) {
console.log(err);
}
})
This is a feature available since ES6 so should work fine. See the docs here for more info
I'm using Loopback v3 currently and wanted to upsert many records at once in a collection; I found this method bulkUpsert from the documentation (http://apidocs.loopback.io/loopback/#persistedmodel-bulkupdate) but I couldn't figure out how to make it work.
How can I create the updates array from createUpdates() method as mentioned in the documentation? Can anyone help me with a simple example of using this method?
There is an alternative way to do the bulkUpdate method, found in Stackoverflow MongoDB aggregation on Loopback
A mixin can be easily created and reused over the Models. My sample code of bulkUpsert mixin is below:
Model.bulkUpsert = function(body, cb) {
try {
Model.getDataSource().connector.connect(async (err, db) => {
if (err) {
return cb(err);
}
// Define variable to hold the description of the first set of validation errors found
let validationErrors = '';
// Build array of updateOne objects used for MongoDB connector's bulkWrite method
const updateOneArray = [];
// Loop through all body content and stop the loop if a validation error is found
const hasError = body.some(row => {
// Check if it is a valid model instance
const instance = new Model(row);
if (!instance.isValid()) {
// A validation error has been found
validationErrors = JSON.stringify(instance.errors);
// By returning true we stop/break the loop
return true;
}
// Remove ID in the row
const data = JSON.stringify(row);
delete data.id;
// Push into the update array
updateOneArray.push({
updateOne: {
filter: { _id: row.id },
update: { $set: Object.assign({ _id: row.id }, data) },
upsert: true
}
});
// No validation error found
return false;
});
// Check if a validation error was found while looping through the body content
if (hasError) {
return cb(new Error(validationErrors));
}
// No validation data error was found
// Get database collection for model
const collection = db.collection(Model.name);
// Execute Bulk operation
return collection.bulkWrite(updateOneArray, {}, (err, res) => {
// Check if the process failed
if (err) {
console.err('The bulk upsert finished unsuccessfully', err);
return cb(err);
}
// Check if there were errors updating any record
if (res.hasWriteErrors()) {
console.error(`The bulk upsert had ${res.getWriteErrorCount()} errors`, res.getWriteErrors());
}
// Finished successfully, return result
return cb(null, {
received: body.length,
handled: res.upsertedCount + res.insertedCount + res.matchedCount
});
});
});
}
catch (err) {
console.error('A critical error occurred while doing bulk upsert', err);
return cb(err);
}
return null;
};
Ref: Mongodb query documentation
I'm currently trying to remove multiple documents references (objectId) when i'm removing those documents.
So this is my code to remove multiple documents and their references:
Comment.find({parentCommentId: req.params.id}).stream()
.on('data', function (comment) {
comment.remove(function (err, result) {
if (err){
console.log(err)
}
console.log(result);
})
})
.on('error', function(err){
// handle error
})
.on('end', function(){
res.status(200).json({
title: 'Comments deleted'
});
});
(this is the middleware i use)
schema.post('remove', function (comment) {
Project.findById(comment.project, function (err, project) {
if(err){
console.log('error : '+ err)
}
project.comments.pull(comment);
project.save();
});
User.findById(comment.user, function (err, user) {
if(err){
console.log('error : '+ err)
}
user.comments.pull(comment);
user.save();
});
});
At the moment i tried multiple things but i kinda got stuck: it removes all the documents i wanted but it always only removes the first document's reference and keeps the other ones.
at this point i don't really understand why.
Have a good day : )
I have an embedded image document in my main document and I am able to update it as follows. Everytime it updates, it just overrides the existing image and does not add it to the existing images.. I tried by "{images.push: image}", but that does not work. what is the syntax ? I am not sure if i am able to explain the problem. if not, please let me know if i need to add more info here.
var image = {
img : new_file_name,
orig_img_name : files.source.filename,
caption : fields.message,
upload_date : new Date()
};
RentModel.update({'facebook_id':fb_id, 'prop_location.lat':lat, 'prop_location.lng':lng}, {'images':image}, function(err, docs){
if(err) {
console.log("Error during friends update");
throw err;
}
console.log('image updated to database', new_file_name);
});
try to find() the embedded document first and then add the image to the array.
RentModel.find({'facebook_id':fb_id, 'prop_location.lat':lat, 'prop_location.lng':lng}, function (err, item) {
if (err) //throw ...
if (item) {
if (item.images && item.images.length) {
item.images.push(image);
}
else {
item.images = [image];
}
// save changes
item.save(function (err) {
if (!err) {
// done ...
}
});
}
});