Just wondering if there is a way to set my meteor subscription to load only new documents from a mongo collection, avoiding to sync deletes and updates (Since they are not relevant in the data that is shown to user).
Why I need that? It seems anytime I do a Meteor.subscribe after an offline period, the WHOLE collection is sent again from server to client, while I only need the new records.
I think this happen to keep local/remote database integrity, but since my app is planned to work online/offline (I'm using also groundDB), it seems to me It will be very inefficient in terms of data usage.
Thanks in advance.
You can create a publish which sends only new documents. Like:
Meteor.publish('newDocumentsOnly', () => {
let initializing = true;
const handle = Collection.find().observeChanges({
added: (id, fields) => {
if (initializing) return;
this.added('Collection', id, fields);
}
});
initializing = false;
this.ready();
this.onStop(() => {
handle.stop();
});
});
Related
I have a REST api which has this endpoint for getting an assignment -
'/classes/<str:code>/assignments/<int:assignment_id>'
I have created a custom hook for querying an Assignment:
const getAssignment = async ({ queryKey }) => {
const [, code, assignmentId] = queryKey
const { data } = await api.get(`/classes/${code}/assignments/${assignmentId}`)
return data
}
export default function useAssignment(code, assignmentId) {
return useQuery(['assignment', code, assignmentId], getAssignment)
}
This works as expected, but is this the right way to deal with relational data in react-query?
code looks right to me. react-query doesn't have a normalized cache, just a document cache. So if you request assignments with a different query key, e.g. assignments for a user, they will be cache separately.
The straight forward approach to tackle this would then be to structure your query keys in a way that you can invalidate everything at the same time.
People register for an event. There are two collections in the database. One for new registrations coming in and one for the registrations of previous years. Both contain an email field as unique identifier.
I would like to know if its possible to check if a newly registered person has registered before in previous years. If so add a field, for example: returningCustomer: true. Otherwise add returningCustomer: false
I am using Mongoose and have a User model for new registrations. I don't have a model (yet) for previously registered users. Would that be neccesary? If it is possible to check if a person has registered before and a field can be added before saving, it might be handy to save the user to the returning customers collection immediatly as well.
I know it is possible to access the current document and collection using a pre save hook, but how about doing a lookup in another collection, write a bit of logic and add a field to the current document pre save?
userSchema.pre('save', function (doc, next) {
const exists = otherCollection.find({ email: doc.email });
exists ? doc.returningCustomer = true : doc.returningCustomer = false;
next();
});
You should have a model for the collection you want to lookup.
Then you can query the other collection before saving the current collection.
CurrentModel.pre('save', async function (next) {
const doc = await OtherModel.find({ field: this.field });
doc.length ? this.returningCustomer = false : this.returningCustomer = true;
next();
});
import {favRestaurants} from '/lib/collections';
import {Meteor} from 'meteor/meteor';
import {check} from 'meteor/check';
export default function () {
Meteor.methods({
'favRestaurants.create' (id, name, rating, priceLevel, type) {
check(id, String);
check(name, String);
check(rating, Number);
check(priceLevel, Number);
check(type, String);
const createdAt = new Date();
const restaurant = {id, name, rating, priceLevel, type, createdAt};
if(check(Meteor.user()) == null){
console.log('onlye logged in users can data');
}else{
FavRestaurants.insert(restaurant);
}
}
});
}
This is my insert method for adding data to the restaurants collections. When i console log the 'check(Meteor.user())' in the console i get null as output. By that logic you shouldn't be able to add data to the collection, although this is still possible.
I would also like to make the FavResaurants collection personal for each user. Iv'e tried to check if there is a user and then adding a collection in the main.js file on the client side.
Meteor.loggingIn(() => {
console.log('check for user method');
var restId = 0;
if(Meteor.user() != null){
console.log('created new collection for the user');
const FavRestaurants = new Mongo.Collection('favRestaurants' + restId);
}
restId++;
});
I dont get any output to console using this method, which i found in the meteor docs. Is the code in the wrong place? Any help is much appriciated.
According to the docs the Accounts.ui.config is the method i should use. But I'm not sure in code i should put it. So far the placement of this method has resulted in my application crashing.
Answering your first question, to allow only logged-in clients to access a method, you should use something like:
if (!Meteor.userId()) {
throw new Meteor.Error('403', 'Forbidden');
}
Now, I see you want a collection to store favorite restaurants for each user in client side. But as I see it, there'd be only one logged in user per client, so you don't need a separate collection for each user (as the collection is in each client), you can just refer the user with it's id, and then fetch a user's favorite restaurants by a query like:
FavRestaurants.find({user: Meteor.userId()});
Moreover, as the docs suggest, Meteor.loggingIn is a method which tells you if some user is in the process of logging in. What you are doing is over-riding it, which doesn't make sense.
You should do something like:
if (Meteor.loggingIn()) {
// Do your stuff
}
Hope it gives you more clarity.
Creating a collection per user is a bad approach.
Define your favRestaurants collection once and add a owner field in the restaurant document before insert.
Create a publish method to publish to client side the userid favrestaurant only.
One more thing, check your userid first in your Meteor method, it will avoid unnecessary proces.
Regs
I have two collections A + B. Both are created at the same event. B is created some lines before A. Now I need to store in A the _id of B. How do I get the id of the just created B?
I am new to meteor and mongoDB, is the _id internally passed back on creation so that it is already available (I did not find an indication for this) or do I need to reread B? If so how do I do this best?
EDIT
I understand that the _id is passed back on the server after the insert.
Client:
Meteor.call('addB',b );
Server:
'addB':function(b){
return B.insert(b);
},
How can I pass B._id to the client so that I can do, on the client, something like:
a.id_of_B = B._id
Meteor.call('addA',a );
collection.insert returns the value of the created _id field. The docs says "Returns its unique _id.".
To return the values to the client a simple callback can be used:
Here again the link to the docs collection.insert
Client:
Meteor.call('addB',b function(error, result) {
BId = result;
});
Server:
'addB':function(b){
return B.insert(b);
},
Remember that in general you don't need Meteor.call() to insert into a collection. You can do both inserts on the client (if the collections are available there) and these inserts will automatically be synchronized back to the server.
var a = {...}; // some object
var b = {...}; // some other object
B.insert(b,function(err,id){ // asynchronous style
a.idOfB = id;
A.insert(a);
})
a.idOfB = B.insert(b); // synchronous style
A.insert(a);
I'm trying to add data to my mongo database with mongoose, but there is a high probability that most of the data is already in the database, only a small number of fields need to be updated. Creation time for the record and last time updated need to be saved.
My first attempt at solving this problem included using the Model.save function, given that my model is called server, and data is an object coming from an external http service, which specifies the unique _id in data.
var instance = new Server(data);
instance.save(function(err){
if(err)
console.log(err);
});
also my pre-save hook:
ServerSchema.pre('save', function(next) {
this.lastseen = Date.now();
if (!this.isNew)
return next() //if the entry isn't new, lets not change the date registred
this.registered = Date.now();
next() //Don't forget this!
})
The problem here is that on duplicate _id the save chokes, with error E11000 duplicate key error index...
This now makes sense as save only does an update when the document instance is not created using the new operator.
So in my next attempt, I added code to attempt to lookup the document, then used underscore.js's _.extend to merge the new document with the one found in the database, then saved that to the database. The problem with this approach is that it require an extra call to the database for each chunk of data being processed.
My third attempt uses the Model.findByIdAndUpdate with {upsert:true} this works, in terms of stroring the data in the database, but schema defaults and my pre-save hook isn't triggered.
The fourth attempt uses code suggested by #aheckmann in this gist: https://gist.github.com/2764948
var server = new Server();
server.init(ping);
server.save(function(err){
if(err) {
console.log("DB Error: ",err);
return res.send('DB Error')
}
//if server approved, tell the inworld server to sync textures
if(server.approved)
res.send('success')
else
res.send('skip')
user.servers.addToSet(ping._id); //add the server to the user's list
user.save(function(err, usr){
if(err)
console.log("DB Error: ", err);
})
})
Here again, the pre-save hook isn't triggered. Am I to understand that the only to upsert with hooks is to attempt to find the document first with a findById ?
Q:
Is there a way to "upsert" Insert or Update based on the primary unique key without making more than one database call per chunk of data? Is there a method, or obvious fact that I am overlooking?
I don't think that you can do it with less then two calls to DB, unless you'll drop mongoose part and use mongo driver directly. But you can create a static method to do all the job for you:
ServerSchema.statics.findOrCreate(function(doc, next) {
this.findById(doc._id, function(err, res) {
res || (res = new this);
_.extend(res, doc); // add new data to the document
next(err, res); // if (err != null) then something went wrong
});
});
findByIdAndUpdate not triggers presave hook because it calls mongo driver directly.