I have difficult time to get latest bucket documents after any operation (insert/delete). I use node.js + express + couchbase, and here's my code, derived from its official website. it basically just a simple address book web-app and has three function: insert, show or delete contact.
After delete or insert operation, I use res.redirect("\") to reload my page. The problem is: it just show old data, only after I reload it for second time, it shows up. I just don't know what's wrong here. Can anybody help?
/* GET home page. */
router.get('/', function(req, res) {
var query = ViewQuery.from('view_people', 'by_id');
bucket.query(query, function(err, results){
return res.render('index', {people: results});
});
});
/* INSERT Contact here */
router.post('/insert', function(req, res){
var name = req.body.name;
var address = req.body.address;
var job = req.body.job;
var age = req.body.age;
bucket.insert(name, {
name : name,
address : address,
job : job,
age : age
}, function(err, reply){
if(err) return res.send(err);
return res.redirect('/');
})
});
/* REMOVE the contact */
router.get('/remove', function(req, res){
var id = req.query.id;
bucket.remove(id, function(err, response){
if (err) {return res.send(err);}
return res.redirect('/');
})
});
module.exports = router;
In Couchbase, views are eventually consistent and it looks like you are using views, thus the lag you are seeing. You'd be better off getting the document by key if you can, then Couchbase is strongly consistent. You'd get the most performance if you had a meta-data object that is a manual index of all of that user's contacts. Then when you want their contacts, you pull that meta-data object, then do a parallelized bulk get of the objects you want by key. That should perform VERY well and do the exact same thing. On top of that, you have a key pattern that uniquely identifies the object to the user.
Another option is to have a counter object per user that is a key value with just the counter. So For example have a key pattern
username::contacts::counter
Filled out, the object's key might look like
hernandez94::contacts::139
the counter would be the upper bound of the array of contacts for that user. to get the most recent contact, you just get the counter object, take that integer, construct the key and get exactly that object. It'd be very fast. To get all contacts, you get the counter object and then generate the keys to do a parallelized bulk get. Again, that'd be very fast. No querying, just raw speed that scales consistently.
Looks like you need to use stale=false in your view query . See : https://forums.couchbase.com/t/how-does-stale-query-work/870
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 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!
I know it will be a trivial thing, but for this, I have not found much around, I'm using node/express js to query a database (MySQL), I'm using the following mode for queries:
index.js
exports.view= function(req, res){
var name = req.params.name;
req.getConnection(function(err,connection){
var query = connection.query('SELECT * FROM event WHERE linkname = ?',[name],function(err,rows)
{
if(err){
console.log("Error Selecting : %s ",err );
res.redirect('/');
}else{
console.log("rows: %s",rows);
var body = JSON.parse(JSON.stringify(rows));
console.log("body: %s",body);
res.render('form_payment',{page_title:"Showroom",data:rows});
}
});
});
};
I would like to view the video, or in any case be able to use part of the query data, I read that you can use JSON.stringify(), JSON.parse() or both, but I always print the empty string on the screen, even when I try to print rows:
rows:
body:
The query works perfectly, in fact, I can pass the json of rows to the next activity with res.render (), but in this function (view) I just can not get and then use this data. My idea would be to be able to easily use the contents of rows, for example, something like rows[0].name, rows[0].id or rows.name, rows.code, ...
[SOLVED]
Remember to check if the variables that are passed to the query are correct, once this problem has been solved everything is back to work correctly and access to the rows elements, can occur with rows[0].id, rows[0].name, ...
I hope you can also help you find yourself in this situation.
I actually have 2 questions. One is what is the best way to go about adding other information to my user object? I have a very simple passportjs login/register system and I want to expand and also add things like coins and other things that are specific to a user's account. Currently, I just added a new property called "coins" along with the password/email and stuff.
My second question is with my coins property for my user object, how do I edit it? Currently I just have a simple request to add a coin for the user and it isn't working.
router.get('/coin', function(req, res) {
User.getUserByUsername(req.user.username, function(err, user){
user.coins = user.coins + 1
console.log(user.coins)
});
res.redirect('/')
});
It is just console logging 1 every time I press the button(the button calls for /coin)
You are loading the user, incrementing one coin, but you are not saving it. So, every time you call the function, load previous state of User.
You should call User.update or whatever as the function of your api is called to save the user data before redirecting.
router.get('/coin', function(req, res) {
User.getUserByUsername(req.user.username, function(err, user){
user.coins = user.coins + 1
User.update(user) // Stores modified data.
console.log(user.coins)
});
res.redirect('/')
});
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