Subscribing to Meteor.Users Collection - mongodb

// in server.js
Meteor.publish("directory", function () {
return Meteor.users.find({}, {fields: {emails: 1, profile: 1}});
});
// in client.js
Meteor.subscribe("directory");
I want to now get the directory listings queried from the client like directory.findOne() from the browser's console. //Testing purposes
Doing directory=Meteor.subscribe('directory')/directory=Meteor.Collection('directory') and performing directory.findOne() doesn't work but when I do directory=new Meteor.Collection('directory') it works and returns undefined and I bet it CREATES a mongo collection on the server which I don't like because USER collection already exists and it points to a new Collection rather than the USER collection.
NOTE: I don't wanna mess with how Meteor.users collection handles its function... I just want to retrieve some specific data from it using a different handle that will only return the specified fields and not to override its default function...
Ex:
Meteor.users.findOne() // will return the currentLoggedIn users data
directory.findOne() // will return different fields taken from Meteor.users collection.

If you want this setup to work, you need to do the following:
Meteor.publish('thisNameDoesNotMatter', function () {
var self = this;
var handle = Meteor.users.find({}, {
fields: {emails: 1, profile: 1}
}).observeChanges({
added: function (id, fields) {
self.added('thisNameMatters', id, fields);
},
changed: function (id, fields) {
self.changed('thisNameMatters', id, fields);
},
removed: function (id) {
self.removed('thisNameMatters', id);
}
});
self.ready();
self.onStop(function () {
handle.stop();
});
});
No on the client side you need to define a client-side-only collection:
directories = new Meteor.Collection('thisNameMatters');
and subscribe to the corresponding data set:
Meteor.subscribe('thisNameDoesNotMatter');
This should work now. Let me know if you think this explanation is not clear enough.
EDIT
Here, the self.added/changed/removed methods act more or less as an event dispatcher. Briefly speaking they give instructions to every client who called
Meteor.subscribe('thisNameDoesNotMatter');
about the updates that should be applied on the client's collection named thisNameMatters assuming that this collection exists. The name - passed as the first parameter - can be chosen almost arbitrarily, but if there's no corresponding collection on the client side all the updates will be ignored. Note that this collection can be client-side-only, so it does not necessarily have to correspond to a "real" collection in your database.
Returning a cursor from your publish method it's only a shortcut for the above code, with the only difference that the name of an actual collection is used instead of our theNameMatters. This mechanism actually allows you to create as many "mirrors" of your datasets as you wish. In some situations this might be quite useful. The only problem is that these "collections" will be read-only (which totally make sense BTW) because if they're not defined on the server the corresponding `insert/update/remove' methods do not exist.

The collection is called Meteor.users and there is no need to declare a new one on neither the server nor the client.
Your publish/subscribe code is correct:
// in server.js
Meteor.publish("directory", function () {
return Meteor.users.find({}, {fields: {emails: 1, profile: 1}});
});
// in client.js
Meteor.subscribe("directory");
To access documents in the users collection that have been published by the server you need to do something like this:
var usersArray = Meteor.users.find().fetch();
or
var oneUser = Meteor.users.findOne();

Related

Mongoose Querying Views

I'm currently using mongoose v. 5.25, against mongoDB v.3.6.
My application is supposed to query data from many different views, for instance, a view I currently have at my DB: db.joboffers_view.find()
will return many records that have been aggregated from different collections.
For a normal collection model, I query it like so:
const model = db.model(attribute);
/*where attribute, can be any registered schema */
model.find().
then((result) => {
resolve(result);
}).
catch((err) => {
reject(err);
});
Then way I register my models is something like this (simplified code):
//...
//abstracting boring connection methods
const db = mongoose.connection
//...
//simple model schema
const users_schema = {
_id: ObjectId,
another_field: String
};
//here I'm registering a schema for a VIEW, instead of normal collection
const view_schema = {
_id: ObjectId,
another_field: String
};
//...
//then
db.model('users', users_schema);
db.model('view', view_schema);
When I run a query from any of my registered models, I get the results just fine. However, when I run it against a model that represents a view on my mongo database, it returns an empty array.
No errors, no nothing, just an empty array.
I have looked through mongoose documentation, and I didn't find any specific method or pattern for querying a view, instead of a collection data.
It seems to be the same way I would do for any other collection I have in my system.
Am I missing something?
I also faced the same issue and figured out the problem is that mongoose, by default, reads collection names by pluralizing the model/view name.
So when you create any view and want to use it in mongoose, either make sure your view name is plural (add s to end of view name) or pass a collection name when initializing a schema.
Example
const users_schema = {
_id: ObjectId,
another_field: String
};
mongoose.model('vw_user_info', users_schema, 'vw_user_info');
I have same problem, but i solved it, please check the name of the view in mongodb, it must be same with db.model('view_name', view_schema);
You can open Mongoose debug by config like this mongoose.set('debug', true);
Add 3rd argument
db.model('view', view_schema, 'view_name_in_db')

Meteor: Increment DB value server side when client views page

I'm trying to do something seemingly simple, update a views counter in MongoDB every time the value is fetched.
For example I've tried it with this method.
Meteor.methods({
'messages.get'(messageId) {
check(messageId, String);
if (Meteor.isServer) {
var message = Messages.findOne(
{_id: messageId}
);
var views = message.views;
// Increment views value
Messages.update(
messageId,
{ $set: { views: views++ }}
);
}
return Messages.findOne(
{_id: messageId}
);
},
});
But I can't get it to work the way I intend. For example the if(Meteor.isServer) code is useless because it's not actually executed on the server.
Also the value doesn't seem to be available after findOne is called, so it's likely async but findOne has no callback feature.
I don't want clients to control this part, which is why I'm trying to do it server side, but it needs to execute everytime the client fetches the value. Which sounds hard since the client has subscribed to the data already.
Edit: This is the updated method after reading the answers here.
'messages.get'(messageId) {
check(messageId, String);
Messages.update(
messageId,
{ $inc: { views: 1 }}
);
return Messages.findOne(
{_id: messageId}
);
},
For example the if(Meteor.isServer) code is useless because it's not
actually executed on the server.
Meteor methods are always executed on the server. You can call them from the client (with callback) but the execution happens server side.
Also the value doesn't seem to be available after findOne is called,
so it's likely async but findOne has no callback feature.
You don't need to call it twice. See the code below:
Meteor.methods({
'messages.get'(messageId) {
check(messageId, String);
var message = Messages.findOne({_id:messageId});
if (message) {
// Increment views value on current doc
message.views++;
// Update by current doc
Messages.update(messageId,{ $set: { views: message.views }});
}
// return current doc or null if not found
return message;
},
});
You can call that by your client like:
Meteor.call('messages.get', 'myMessageId01234', function(err, res) {
if (err || !res) {
// handle err, if res is empty, there is no message found
}
console.log(res); // your message
});
Two additions here:
You may split messages and views into separate collections for sake of scalability and encapsulation of data. If your publication method does not restrict to public fields, then the client, who asks for messages also receives the view count. This may work for now but may violate on a larger scale some (future upcoming) access rules.
views++ means:
Use the current value of views, i.e. build the modifier with the current (unmodified) value.
Increment the value of views, which is no longer useful in your case because you do not use that variable for anything else.
Avoid these increment operator if you are not clear how they exactly work.
Why not just using a mongo $inc operator that could avoid having to retrieve the previous value?

Query sailsjs blueprint endpoints by id array using request

I'm using the request library to make calls from one sails app to another one which exposes the default blueprint endpoints. It works fine when I query by non-id fields, but I need to run some queries by passing id arrays. The problem is that the moment you provide an id, only the first id is considered, effectively not allowing this kind of query.
Is there a way to get around this? I could switch over to another attribute if all else fails but I need to know if there is a proper way around this.
Here's how I'm querying:
var idArr = [];//array of ids
var queryParams = { id: idArr };
var options: {
//headers, method and url here
json: queryParams
};
request(options, function(err, response, body){
if (err) return next(err);
return next(null, body);
});
Thanks in advance.
Sails blueprint APIs allow you to use the same waterline query langauge that you would otherwise use in code.
You can directly pass the array of id's in the get call to receive the objects as follows
GET /city?where={"id":[1, 2]}
Refer here for more.
Have fun!
Alright, I switched to a hacky solution to get moving.
For all models that needed querying by id arrays, I added a secondary attribute to the model. Let's call it code. Then, in afterCreate(), I updated code and set it equal to the id. This incurs an additional database call, but it's fine since it's called just once - when the object is created.
Here's the code.
module.exports = {
attributes: {
code: {
type: 'string'//the secondary attribute
},
// other attributes
},
afterCreate: function (newObj, next) {
Model.update({ id: newObj.id }, { code: newObj.id }, next);
}
}
Note that newObj isn't a Model object as even I was led to believe. So we cannot simply update its code and call newObj.save().
After this, in the queries having id arrays, substituting id with code makes them work as expected!

How to call cascading find() in Meteor + MongoDB?

I use Meteor & Iron-router. I have the following data context defined in the router:
data: function() { return {
eventId: this.params._id,
registrants: Registrants.find({eventIds: {$elemMatch: { $in: [this.params._id]}}}, {sort: {name:1, phone:1, email:1}}),
}}
I want to enable Registrants to be filtered further by user input. In my case, I already have ReactiveVar called filterName which listen to input text from user. Whenever the input text changed, the filterName is updated. ( I followed this answer ng-repeat + filter like feature in Meteor Blaze/Spacebars)
Now, I want to add $and to the Registrants.find() method to derive new registrants data context. How should I do it so that the query is reactive to the filterName?
Another approach is by defining Template helper method filteredRegistrants. Initially, its value is the same as return this.registrants. Whenever filterName changed, I would do return this.registrants.find({name: filterName}), but somehow I can't invoke find from registrants cursor, can I? I got undefined is not function error when doing that.
this.registrants is already a cursor (result of Registrants.find()), and not a collection, thus it doesn't have the find() method you look for. However, there is nothing wrong with making another query in the helper if the functionality provided by your controller is not enough:
Template.registrantsTemplate.helpers({
filteredRegistrants: function() {
return Registrants.find(...query...);
},
});

Mongoose - update after populate (Cast Exception)

I am not able to update my mongoose schema because of a CastERror, which makes sence, but I dont know how to solve it.
Trip Schema:
var TripSchema = new Schema({
name: String,
_users: [{type: Schema.Types.ObjectId, ref: 'User'}]
});
User Schema:
var UserSchema = new Schema({
name: String,
email: String,
});
in my html page i render a trip with the possibility to add new users to this trip, I retrieve the data by calling the findById method on the Schema:
exports.readById = function (request, result) {
Trip.findById(request.params.tripId).populate('_users').exec(function (error, trip) {
if (error) {
console.log('error getting trips');
} else {
console.log('found single trip: ' + trip);
result.json(trip);
}
})
};
this works find. In my ui i can add new users to the trip, here is the code:
var user = new UserService();
user.email = $scope.newMail;
user.$save(function(response){
trip._users.push(user._id);
trip.$update(function (response) {
console.log('OK - user ' + user.email + ' was linked to trip ' + trip.name);
// call for the updated document in database
this.readOne();
})
};
The Problem is that when I update my Schema the existing users in trip are populated, means stored as objects not id on the trip, the new user is stored as ObjectId in trip.
How can I make sure the populated users go back to ObjectId before I update? otherwise the update will fail with a CastError.
see here for error
I've been searching around for a graceful way to handle this without finding a satisfactory solution, or at least one I feel confident is what the mongoosejs folks had in mind when using populate. Nonetheless, here's the route I took:
First, I tried to separate adding to the list from saving. So in your example, move trip._users.push(user._id); out of the $save function. I put actions like this on the client side of things, since I want the UI to show the changes before I persist them.
Second, when adding the user, I kept working with the populated model -- that is, I don't push(user._id) but instead add the full user: push(user). This keeps the _users list consistent, since the ids of other users have already been replaced with their corresponding objects during population.
So now you should be working with a consistent list of populated users. In the server code, just before calling $update, I replace trip._users with a list of ObjectIds. In other words, "un-populate" _users:
user_ids = []
for (var i in trip._users){
/* it might be a good idea to do more validation here if you like, to make
* sure you don't have any naked userIds in this array already, as you would
*/in your original code.
user_ids.push(trip._users[i]._id);
}
trip._users = user_ids;
trip.$update(....
As I read through your example code again, it looks like the user you are adding to the trip might be a new user? I'm not sure if that's just a relic of your simplification for question purposes, but if not, you'll need to save the user first so mongo can assign an ObjectId before you can save the trip.
I have written an function which accepts an array, and in callback returns with an array of ObjectId. To do it asynchronously in NodeJS, I am using async.js. The function is like:
let converter = function(array, callback) {
let idArray;
async.each(array, function(item, itemCallback) {
idArray.push(item._id);
itemCallback();
}, function(err) {
callback(idArray);
})
};
This works totally fine with me, and I hope should work with you as well