I'm trying building an application using MongoDB, Mongoose, JQuery, and Node.js. Whenever I try to add to an array within my Schema sometimes it will add that item several times.
Schema
This is my schema, I'm trying to add the my upvote and downvote arrays that keep track of users that voted by their id.
var SuggestionSchema = new mongoose.Schema({
title: String,
content: String,
link: String,
upvote: [{
user_id: {
type: Schema.ObjectId,
ref: 'User'
}
}],
downvote: [{
user_id: {
type: Schema.ObjectId,
ref: 'User'
}
}],
user_id: {
type: Schema.ObjectId,
ref: 'User'
},
category_id: {
type: Schema.ObjectId,
ref: 'Category'
},
});
Route and Query
Here is my put route and query
router.put('/:suggestion_id/downvote', function(req, res, next) {
Suggestion.findByIdAndUpdate(
req.params.suggestion_id,
{$push: {"downvote": req.body}},
function(err, suggestion) {
res.json(suggestion);
})
});
Ajax Call with Jquery
This is my PUT request that is triggered on a click.
$('#downvote').click(function(){
var user = {
user_id: current_user._id
}
$.ajax({
url: current_url + "suggestions/" + current_suggestion + '/downvote',
type: 'PUT',
data: user,
success: function(data){
//callback
}
});
}
Results
Two other things to note:
The console will return:
Failed to load resource: net::ERR_EMPTY_RESPONSE
AND
Ultimately just clicking once sometimes results in 2 or 3 of the same user being pushed into the downvote array in the Schema. I put some safeguards on the front end that checks if the user has already voted, but it still seems to put through multiple times so I think it's a different issue. I believe I'm just approaching it wrong or missing something fundamental. I've only been coding for 6 months so I'm still learning. Thanks!
Instead of using the $push operator to push the user id object to the downvote array, use the $addToSet operator. This adds a value to an array unless the value is already present, in which case $addToSet does nothing to that array. It only ensures that there are no duplicate items added to the set and does not affect existing duplicate elements. If the field is absent in the document to update, $addToSet creates the array field with the specified value as its element. So you final route will look like:
router.put('/:suggestion_id/downvote', function(req, res, next) {
Suggestion.findByIdAndUpdate(
req.params.suggestion_id,
{$addToSet: {"downvote": req.body}},
function(err, suggestion) {
res.json(suggestion);
}
);
});
Related
I'm trying to use Mongoose (MongoDB JS library) to create a basic database, but I can't figure out how to delete the documents / items, I'm not sure what the technical term for them is.
Everything seems to work fine, when I use Item.findById(result[i].id), it returns a valid id of the item, but when I use Item.findByIdAndDelete(result[i].id), the function doesn't seem to start at all.
This is a snippet the code that I have: (Sorry in advance for bad indentation)
const testSchema = new schema({
item: {
type: String,
required: true
},
detail: {
type: String,
required: true
},
quantity: {
type: String,
required: true
}
})
const Item = mongoose.model("testitems", testSchema)
Item.find()
.then((result) => {
for (i in result) {
Item.findByIdAndDelete(result[i].id), function(err, result) {
if (err) {
console.log(err)
}
else {
console.log("Deleted " + result)
}
}
}
mongoose.connection.close()
})
.catch((err) => {
console.log(err)
})
I'm not sure what I'm doing wrong, and I haven't been able to find anything on the internet.
Any help is appreciated, thanks.
_id is a special field on MongoDB documents that by default is the type ObjectId. Mongoose creates this field for you automatically. So a sample document in your testitems collection might look like:
{
_id: ObjectId("..."),
item: "xxx",
detail: "yyy",
quantity: "zzz"
}
However, you retrieve this value with id. The reason you get a value back even though the field is called _id is because Mongoose creates a virtual getter for id:
Mongoose assigns each of your schemas an id virtual getter by default which returns the document's _id field cast to a string, or in the case of ObjectIds, its hexString. If you don't want an id getter added to your schema, you may disable it by passing this option at schema construction time.
The key takeaway is that when you get this value with id it is a string, not an ObjectId. Because the types don't match, MongoDB will not delete anything.
To make sure the values and types match, you should use result[i]._id.
I want to create a social network thus allowing users to send and interact with frind requests. As of now I have created the register, log-in and "search for other users function".
When I find and select another user, I display their user-info and have created a "Add friend" button.
Can anyone help me in a direction of the creation of the "Add friend" option? I have looked around for some time now, and not been able to find the correct solution. Below I have attached my UserSchema and route for finding users:
//User Schema
const UserSchema = new mongoose.Schema({
firstName: {
type: String,
required: true
},
lastName: {
type: String,
required: true
},
password: {
type: String,
required: true
},
},{ collection: 'Users' });
//Get single user based on ID
router.get('/user/get:id', ensureAuthenticated, function (req, res) {
MongoClient.connect(DBUri,{useUnifiedTopology: true }, function (err, db) {
let dbo = db.db(DBName);
const query = {_id: objectId(req.params.id)}
dbo.collection("Users").find(query).toArray(function(err, resultTasks) {
if (err) throw err;
res.render('../View/findFriend', {
resultTasks: resultTasks
});
db.close();
});
});
});
You can add something like this in your user schema:
friends: [{ type : ObjectId, ref: 'User' }],
OR
friends: userSchema
Take the one which suits you.
What that will do is add an array to the user, Then you can store IDs of friends.(Who are other users, hence the ref: 'User')
Then, When you have to fetch users you can do:
User.find(<ID or whatever you have to find Users>).populate('friends')
Also, To push a new friend simply use: user.friends.push(newFriend._id)
I have a document Project with an array of subdocuments, with a schema Tasks. Tasks has an array of subdocuments with a schema Comments.
const projectSchema = new Schema({
_id: Schema.Types.ObjectId,
name: { type: String, required: true, unique: true },
description: { type: String, default: '' },
tasks: [{ type: Schema.Types.ObjectId, ref: 'Threads' }]
});
module.exports = mongoose.model('Project', projectSchema);
const tasksSchema = new Schema({
projectId: { type: Schema.Types.ObjectId },
_id: Schema.Types.ObjectId,
title: { type: String, required: true },
text: { type: String, required: true },
comments: [{ type: Schema.Types.ObjectId, ref: 'Replies' }]
})
module.exports = mongoose.model('Tasks', tasksSchema);
const commentSchema = new Schema({
taskId: { type: Schema.Types.ObjectId },
_id: Schema.Types.ObjectId,
text: { type: String, required: true }
})
module.exports = mongoose.model('Comment', commentSchema);
When I delete the Project document I want to delete every Task and every Comment relate to that project.
To delete the Project I use findOneAndDelete so I set up a post middleware to delete all the Tasks
projectSchema.post('findOneAndDelete', function(doc, next) {
mongoose.model('Tasks').deleteMany({ projectId: doc._id }).exec();
next();
})
But now I don’t know how to delete every comment, because deletemany returns an object with the result of the operation.
Should I map the array of Tasks and call findOneAndDelete every time and then delete every single comment? It looks very inefficient for a lot of tasks.
How about embedding comments in post? since its one to many(not huge) relation. So in your code where you delete a project, you first delete all posts, which contain all the comments, only after it succeeds you delete the project. It will also benefit your read performance significantly because you just have to return a single post document instead of multiple(1post + many comment) documents.
Embedding post to project could also be possible, but depending on the size and number of possible posts, its probably better to keep it as a separate document.
In this case you need some logic to ensure consistency.
Here you could use mongodb's new feature, transaction. But I think for this case a transaction is not necessary.(Also I find it quite unstable for now) You could go with the "eventual consistency" method.
Basically you just delete all the posts related to a project and then delete a project. And then you run batches to check for any inconsistency.(check if there are any posts where its project doesnt exist. If it doestnt then delete the posts)
I would like to know how to keep track of the values of a document in MongoDB.
It's a MongoDB Database with a Node and Express backend.
Say I have a document, which is part of the Patients collection.
{
"_id": "4k2lK49938d82kL",
"firstName": "John",
"objective": "Burn fat"
}
Then I edit the "objective" property, so the document results like this:
{
"_id": "4k2lK49938d82kL",
"firstName": "John",
"objective": "Gain muscle"
}
What's the best/most efficient way to keep track of that change? In other words, I would like to know that the "objective" property had the value "Burn fat" in the past, and access it in the future.
Thanks a lot!
Maintaining/tracking history in the same document is not all recommended. As the document size will keep on increasing leading to
probably if there are too many updates, 16mb document size limit
Performance degrades
Instead, you should maintain a separate collection for history. You might have use hibernates' Javers or envers for auditing for your relational databases. if not you can check how they work. A separate table (xyz_AUD) is maintained for each table (xyz). For each row (with primary key abc) in xyz table, there exist multiple rows in xyz_AUD table, where each row is version of that row.
Moreover, Javers also support MongoDB auditing. If you are using java you can directly use it. No need to write your own logic.
Refer - https://nullbeans.com/auditing-using-spring-boot-mongodb-and-javers/
One more thing, Javers Envers Hibernate are java libraries. But I'm sure for other programming languages also, similar libraries will be present.
There is a mongoose plugin as well -
https://www.npmjs.com/package/mongoose-audit (quite oudated 4 years)
https://github.com/nassor/mongoose-history#readme (better)
Maybe you can change the type of "objective" to array and track the changes in it. the last one of the array is the latest value.
Maintain it as a sub-document like below
{
"_id": "4k2lK49938d82kL",
"firstName": "John",
"objective": {
obj1: "Gain muscle",
obj2: "Burn fat"
}
}
You can also maintain it as an array field but remember, mongodb doesn't allow you to maintain uniqueness in an array field and if you plan to index the "objective" field, you'll have to create a multi key index
I think the simplest solution would be to use and update an array:
const patientSchema = new Schema({
firstName: { type: String, required: true },
lastName: { type: String, required: true },
objective: { type: String, required: true }
notes: [{
date: { type: Date, default: Date.now() },
note: { type: String, required: true }
}],
});
Then when you want to update the objective...
const updatePatientObjective = async (req, res) => {
try {
// check if _id and new objective exist in req.body
const { _id, objective, date } = req.body;
if (!_id || !objective) throw "Unable to update patient's objective.";
// make sure provided _id is valid
const existingPatient = await Patient.findOne({ _id });
if (!existingPatient) throw "Unable to locate that patient.";
// pull out objective as previousObjective
const { objective: previousObjective } = existingPatient;
// update patient's objective while pushing
// the previous objective into the notes sub document
await existingPatient.updateOne({
// update current objective
$set { objective },
// push an object with a date and note (previouseObjective)
// into a notes array
$push: {
notes: {
date,
note: previousObjective
},
},
}),
);
// send back response
res
.status(201)
.json({ message: "Successfully updated your objective!" });
} catch (err) {
return res.status(400).json({ err: err.toString() });
}
};
Document will look like:
firstName: "John",
lastName: "Smith",
objective: "Lose body fat.",
notes: [
{
date: 2019-07-19T17:45:43-07:00,
note: "Gain muscle".
},
{
date: 2019-08-09T12:00:38-07:00,
note: "Work on cardio."
}
{
date: 2019-08-29T19:00:38-07:00,
note: "Become a fullstack web developer."
}
...etc
]
Alternatively, if you're worried about document size, then create a separate schema for patient history and reference the user's id (or just store the patient's _id as a string instead of referencing an ObjectId, whichever you prefer):
const patientHistorySchema = new Schema({
_id: { type: Schema.Types.ObjectId, ref: "Patient", required: true },
objective: { type: String, required: true }
});
Then create a new patient history document when the objective is updated...
PatientHistory.create({ _id, objective: previousObjective });
And if you need to access to the patient history documents...
PatientHistory.find({ _id });
So I got two mongoose-models:
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var eventSchema = new mongoose.Schema({
name: String,
date: String,
dogs: [{ type: Schema.Types.ObjectId, ref: 'Dog' }]
});
module.exports = mongoose.model('Event', eventSchema);
and
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var dogSchema = new mongoose.Schema({
name: String,
age: String,
gender: String,
});
module.exports = mongoose.model('Dog', dogSchema);
Event contains an array of dogs and im trying to figure out how to add/delete dogs to this array.
On the client I got this method:
$.ajax({
url: "http://localhost:3000/api/events/",
dataType: 'json',
type: 'POST', // Not sure if I should Post or Put...
data: {event_Id : this.props.choosenEvent._id, //Here I got the Id of the Event that i want to update by
dog_Id : this.props.events[dog]._id }, //adding this dog, which Id is here
success: function(data) {
}.bind(this),
});
},
On the server, NodeJs, I got my routes to the API. To me, it makes sense to use an PUT-method and start by getting the right Event with the event_Id passed as a param. Something like:
router.route('/events/:event_id')
.put(function(req, res) {
Event
.findById({ _id: req.param.event_id })
.populate('dogs')
});
But Im stuck at this point. Any help appreciated. Thanks!
Update!
Thank you! Your code helped a lot, you used lodash .remove to delete a dog from the array, is there a similar way to add an item with lodash?
I gave the add method a go like this:
router.route('/events')
.post(function(req, res) {
// Your data is inside req.body
Event
.findById({ _id: req.body.event_Id })
// execute the query
.exec(function(err, eventData) {
// Do some error handing
// Your dogs are inside eventData.dogs
eventData.dogs.push(req.body.dog_Id);
console.log(eventData)
});
// Update your eventDate here
Event.update({_id: req.body.event_id}, eventData)
.exec(function(err, update) {
// Do some error handing
// And send your response
});
});
When I hit the console.log(eventData) I can see that dog_id gets added to the array as it should. However it does not get saved to the db and the error says that eventData is not defined in Event.Update. I suspect this is a Js-scope-issue.
Onte thing that boggles me is this:
Obviously I would like to be able to add and remove dogs from the array and the
route is this: router.route('/events') .
But if both the add-method and the remove-method is on the same route, how can the code know which one I am going for?
There are a few mistakes you are making. First of all, you are making a POST request but your route accepts a PUT request. I have updated your code so it accepts a POST.
When posting objects, your data is inside req.body. req.params is used for url parameters. This is also the case when using a PUT request.
Populating dogs is not really necessary. You are sending your dog_id to your function so you can delete your item from your array which removes your dog from your event. This should do the trick. Please note that this does not remove your dog from your DB but only from your event.
Last but not least. I am using lodash. _.remove is a lodash function. You should definitely check it out, it will help you a lot.
Take a look at my code. It should get you going:
router.route('/events/:event_id')
// Since you are posting, you should use POST from JavaScript instead of PUT
.post(function(req, res) {
// Your data is inside req.body
Event
.findById({ _id: req.body.event_id })
// execute the query
.exec(function(err, eventData) {
// Do some error handing
// Your dogs are inside eventData.dogs
_.remove(eventData.dogs, function(d) {
return d._id === req.body.dog_Id;
});
// Update your eventDate here
Event.update({_id: req.body.event_id}, eventData)
.exec(function(err, update) {
// Do some error handing
// And send your response
});
});
});
UPDATE:
I do not think there is a way to add items to an array with lodash but you can simply use push like you did in your code example. That works just fine.
Your update is not working because your are executing the findById and update at the same time. You will have to find the item first, add the id and THEN update the item :) Move your update function inside the callback of your findById function and that should be fixed. So it looks like this:
router.route('/events')
.post(function(req, res) {
// Your data is inside req.body
Event
.findById({ _id: req.body.event_Id })
// execute the query
.exec(function(err, eventData) {
// Do some error handing
// Your dogs are inside eventData.dogs
eventData.dogs.push(req.body.dog_Id);
console.log(eventData)
// Update your eventDate here
Event.update({_id: req.body.event_id}, eventData)
.exec(function(err, update) {
// Do some error handing
// And send your response
});
});
});
You can add different functions on the same route as long as the method is different from the others. Take a look at REST at this answer. You can have a GET, POST, PUT & DELETE on /events. This is defined by this rule:
router.route('/events').post();