I am new to JS and I am utilizing the MEAN stack to create a place where students can add classes to their user profile. I already have a session store in my database, so "req.user" will return the currently logged in user information and specifically "req.user.id" will return the currently logged in user's id. Also, I have figured out how to search a course in my database from my application. Ultimately, my goal is that when the user makes the post request to search in the database, I also want those "values" to be pushed into the classes "key". I have provided two options, both of which do not add the respective strings to the database. Thank you for any help!
Portion of Search.JS Option #1
router.post('/', ensureAuthenticated, function (req,res,next) {
var query = {course: req.body.coursename};
db.collection('courses').find(query).toArray()
.then(db.collection('DefaultUser').update({_id: req.user.id}, {$push: {classes: req.body.coursename}}));
res.render('search', {title: 'search'})
});
Portion of Search.JS Option #2
router.post('/', ensureAuthenticated, function(req,res,next) {
var query = {course: req.body.coursename};
db.collection('courses').find(query).toArray((err, results) => {
if (err) {
throw err;
} else {
db.collection('DefaultUser').updateOne({_id: '5c17161d3347e79410ff29ba'}, {
$push: {
classes: req.body.coursename
}
})
console.log(results)
res.render('search', {courses: results, title: 'search'})
}
})
});
Some tips may help:
req.body will hold nothing if you forget to use app.use(express.urlencoded()) to parse the posted data.
You may use ObjectId('<string>') (in option #2) for finding and updating queries, not just the string, because mongodb stores _id as ObjectId type by default.
You may use $addToSet instead of $push modifier to add a unique element to an array, or you may get one student subscribed with two more same class, if he repeatedly submit the form.
In your code, you find in the courses collection first and then update, but since you did nothing with the find result, it is not necessary (empty result does not throw any error). Checking the data is valid is good practice, if you would like to do so, in both options, you need to use findOne instead of find to make sure the course is existed, and .then(course => {/* check if the course is null and then throws an error */} ).
I don't have the full code of your project so I can only guess there may be the problems listed above, wish you good luck!
Related
I want to access resources from a SQLite database table. I have one table for accounts, one for movies and one for reviews. The reviews-table is constructed like this:
CREATE TABLE IF NOT EXISTS reviews (
id INTEGER PRIMARY KEY,
authorId INTEGER,
movieId INTEGER,
review TEXT,
rating INTEGER,
FOREIGN KEY('authorId') REFERENCES 'accounts'('id'),
FOREIGN KEY('movieId') REFERENCES 'movies'('id')
)
What I want to do is that I want to be able to get all reviews, made by one author. But I also want to be able to get all reviews, made for the same movie. Below is my code for getting all reviews made by the same user/author. The code looks the same when getting the reviews based on the movie, with a few changes.
Both of them does what I want them to do. But of course only the one written first in the file are running.
const authorId = request.params.authorId;
const query = "SELECT * FROM reviews WHERE authorId = ?";
const values = [authorId];
db.all(query, values, function (error, review) {
if (error) {
response.status(500).end();
} else if (!review) {
response.status(404).end();
} else {
response.status(200).json(review);
}
});
});
The url will look the same no matter which of them I want running; http://localhost:3000/reviews/3. How can I differentiate the url so that they know which one should run?
I have tried to experiment with query strings, but I'm not sure how that works, and after hours of searching for something that worked on my code, I gave up.
I have also been thinking about using something like
app.use(function (request, response, next) {
if (request.method == "GET" && request.uri == "/reviews/:authorId") {
response.send("Hello World");
} else {
next;
}
});
This didn't work, and it didn't work if I tried to remove ":authorId" from the url either. The page just keeps loading.
So how do I solve this?
The most dynamic would be a single route /reviews and use the query string with the params like ?author=123 or ?movie=123, they can be combined like ?author=123&movie=123. As you want to return JSON the code will be used via API, so the pretty path is usually not as important as when it is a web-url. To make the implementation effective, most people use a function where you can drop the query object in and get the where-clause, or use an ORM.
In express, when you have routers like '/reviews/:authorId' and then '/reviews/:movieId', then the second one will never be called, because the first one will always match. That is something to be careful about when organizing your express routes.
I've been trying to build my first solo CRUD app (without following a tutorial) and came across something a little weird which I can't wrap my head around. Apologies if it's rather obvious, but I couldn't find anything on here about it.
I added my delete route for one of my models and used the following code:
// delete list
router.delete("/lists/:id", function(req, res){
// find list by ID and remove it
List.findOneAndRemove(req.params.id, function(err, deletedList){
if(err) {
console.log("ERROR DELETING LIST");
console.log(err);
res.redirect("/lists");
} else {
// if list is removed successfully, remove each item
console.log(deletedList);
Item.remove({_id: {$in: deletedList.items}}, function(err, deletedItems){
if(err) {
console.log("ERROR DELETING ITEMS");
console.log(err);
} else {
console.log("SUCCESSFULLY DELETED LIST & ALL ITEMS");
res.redirect("/lists");
}
});
}
});
});
Now, it deletes things from the database, however it doesn't delete the right thing. I have a button on my web page which submits a form. The form's action is generated based on the page content where I insert the ID of the model into the action using EJS. When I submit the form to delete the model and it's referenced items, it ends up deleting the first document in the database, even though (to my understanding), I've specified that only documents which match the provided ID should be deleted.
I did fix it, by replacing
List.findOneAndRemove(req.params.id, function(err, deletedList){
if(err) {
console.log("ERROR DELETING LIST");
console.log(err);
res.redirect("/lists");
} else {
with
List.findOneAndRemove({_id: {$in: req.params.id}}, function(err, deletedList){
if(err) {
console.log("ERROR DELETING LIST");
console.log(err);
res.redirect("/lists");
} else {
though I'm not completely sure on why this works and req.params.id doesn't. I was just hoping for some clarification in case I come across something similar in the future.
I believe it is deleting the first item in your array because you are using "FindOneAndRemove" - as is suggested in the name, this will limit the match to a single document. And in your first version of the code:
List.findOneAndRemove(req.params.id, function(err, deletedList){
You aren't specifying your _id field, so i believe it is matching everything, and is only removing a single document due to the method you are using. Where as in the second one, you are
List.findOneAndRemove({_id: {$in: req.params.id}}, function(err, deletedList){
Here's a possible reason I can point. When you pass req.params.id to findOneAndRemove, since JS is not a strongly typed language and you are not specifically typing it, Mongoose isn't sure about what to delete.
The first parameter to findOneAndRemove is the filter object and Mongoose is not able to find the right filtering since the data type that is passed here is a string.
I think then Mongoose consider an empty filter and as usual, empty filter deletes the first item.
One try you can do is to explicitly type the _id, say like
var id = new mongoose.mongo.ObjectID(req.params.id)
and pass this id to the findOneAndRemove() function.
Hope this helps.
I am building a web application, and I am spending so long time to take care of updates between related documents.
For example, I have 'Task' document and 'User' document. When task is made, multiple users will be assigned to it. Thus,
taskA.assigned = ["1321231fsdfsdf"(userA's _id), "12312313asdasdasd"(userB's _id)]
userA.tasks = [..., "1231321"(taskA's _id),...]
userB.tasks = [..., "12313211"(taskB's _id),...]
I could handle it well when it comes to just creating tasks. However, it becomes too tricky when I am going to edit tasks. If user B is deleted from taskA, I have to delete userB's id and go to the userB's tasks property and delete taskA's id too.
Is there any shortcut and automatic way to deal with it? Thank you for your time to read it. Let me know if I was too vague, I will add more detail.
In a relational database like MySQL using foreign keys and cascade updates could be done automatically, but in MongoDB that's not possible.
But I see in the tags you are using Moongose, so using a post save hook could do the trick. You can set a hook that updates automatically the user collection each time a task is updated, or viceversa.
Other option would be changing your data estructure, but this depends on your case, there are some facts to take into account. I think we don't have enough information to judge, but there are many resources speaking about data normalization in MongoDB, you can check for example the official MongoDB manual.
I found a way to do this easily and with less lines of codes. Around 100 lines reduced to around 30 lines by doing this.
Long story short, I used 'update()' method and various mongo operators, such as $in, $push, or $pull.
Here is my final codes that are optimized with use of update method.
var edit = req.body;
edit.assignedTo = edit.assignedTo.split(',');
var old = req.task;
var idQueries = edit.assignedTo.map(function (x) {
return mongoose.Types.ObjectId(x);
});
User.update({tasks: old._id}, {$pull: {tasks: old._id}}, {multi: true}, function () {
// Update to remove original task's id from users assigned to it.
User.update({_id: {$in: idQueries}}, {$push: {tasks: old._id}}, {multi: true}, function () {
// Update to add edited tasks'id to new users assigned to it.
old.lastAction = 'edited';
old.edited = true;
old.editedAt = Date.now();
old.titke = edit.title;
old.desc = edit.desc;
old.dueBy = edit.dueBy;
old.assignedTo = edit.assignedTo;
old.save(function (err, task) {
if (err) return next(err);
User.populate(task, 'assignedTo', function (err, task) {
res.json(task);
});
});
});
});
Wish this help some people!
I'm having a big deal - the meteor app I've been developing the last weeks is finally online. But, for an update, I need to add a field to my users profile.
I thought that walling a methods with the following code would work :
updateUsrs_ResetHelps: function(){
if(Meteor.users.update({}, {
$set: {
'profile.helps': []
}
}))
console.log("All users profile updated : helps reset");
else
throw new Meteor.Error(500, 'Error 500: updateUsrs_ResetHelps',
'the update couldn\'t be performed');
}
The problem is that my users have the classic Meteor.accounts document, whith emails, _id, services, profile, etc... but, in the profile, they don't have a .helps fields. I need to create it.
For the future users, I've modified the accounts creation function to add this fields when they sign up, but for the 200 users I already got signed up, I do really need a solution.
EDIT : Might it be because of the selector in the update ? Is a simple {} selector valid to update all the users / documents of the collection at once ?
From the Mongo documentation (http://docs.mongodb.org/manual/reference/method/db.collection.update/):
By default, the update() method updates a single document. Set the
Multi Parameter to update all documents that match the query criteria.
If you've already taken care of adding the field for new users and you just need to fix the old ones, why not just do it one time directly in the database?
Run meteor to start your application, then meteor mongo to connect to the database. Then run an update on records where the field doesn't already exist. Something like:
db.users.update({"profile.helps": {"$exists": false}}, {"$set": {"profile.helps": []}}, {multi:true})
The Mongo documentation specifies the multi parameter as:
Optional. If set to true, updates multiple documents that meet the
query criteria. If set to false, updates one document. The default
value is false.
I have a problem I can't find an answer to in Loopback's docs.
Say I have a model Company and a modelEmployee. There is an 1Xn relation between the Company and its Employees. When /api/Employees is called, server returns all the employees.
I only want to return the list of employees who are in the same company with the user requesting the list.
For this, I created a remote hook
Employee.beforeRemote('find', function(context, modelInstance, next) {
var reject = function() {
process.nextTick(function() {
next(null, false);
});
};
// do not allow anonymous users
var userId = context.req.accessToken.userId;
if (!userId) {
return reject();
}
//I get the details of the user who sent the request
//to learn which company does he belong to
Employee.findById(userId, function(err, user) {
if(!context.req.query.filter) context.req.query.filter={};
context.req.query.filter.where = {brandId:user.companyId};
console.log(context.req.query);
next();
});
});
I thought this should work every time, but appearantly it only works when find already has some query filters like include - although the console.log prints a correct context.req.query object.
What am I missing? Any help would be greatly appreciated!
context.args.filter seems to work for this purpose.
As a side note, instead of replacing where, you might want to merge it with something provided by client. For implementation idea you can refer to: https://github.com/strongloop/loopback-datasource-juggler/blob/master/lib/utils.js#L56-L122