How to do cascaded delete, update and reactive update in existing joined documents? Say for example I join Posts collection with Meteor.users collection with userId() as author. I could do transform function on the Posts collection to get user data of the author, like username and display username of the author on any post. The problem is when user changes his/her username, existing posts won't update author's username reactively. And when you delete parent document child documents are still there. I used popular smart packages like publish-composite and collection-helpers but problem still exists. Any expert meteor dev can help me on this? Thank you.
If you want to use collection-hooks to solve this problem, the following pseudo code should get you going:
// run only on the server where we have access to the complete dataset
if (Meteor.isServer) {
Meteor.users.after.update(function (userId, doc, fieldNames, modifier, options) {
var oldUsername = this.previous.username;
var newUsername = doc.username;
// don't bother running this hook if username has not changed
if (oldUsername !== newUsername) {
Posts.update({
// find the user and make sure you don't overselect those that have already been updated
author: userId,
authorUsername: oldUsername
}, {$set: {
// set the new username
authorUsername: newUsername
}}, {
// update all documents that match
multi: true
})
}
}, {fetchPrevious: true});
}
Related
This Meteor code is working fine, but I would like to ask if it is the way Meteor does things or it is a un predictable side effect that may change under some condition later.
The things is that when I do
DisplayCol.insert({action: 'task1', element: 'p', value: value_variable});
Meteor also inserts the correct userId (using 2 different browsers logged in as 2 different users) which I did not explicitly included in the document.
The above line of code is inside a server side function which is called from Meteor method.
here is the relevant information;
//lib/collection.js
DisplayCol = new Mongo.Collection('displayCol');
//server.js
Meteor.publish('displayCol', function () {
return DisplayCol.find({userId: this.userId});
});
DisplayCol.before.insert(function (userId, doc) {
doc.userId = userId;
});
In the docs of Collection hooks > Additional notes > second bulleted paragraph says:
userId is available to find and findOne queries that were invoked within a publish function.
But this is a collection.insert. So should I explicitly include the userId in the document or let the collection hook do its hidden magic? Thanks
No, there is no hidden magic in that code, your before hook is inserting the userId field in the document.
When you do an insert like this,
DisplayCol.insert({action: 'task1', element: 'p', value: value_variable});
the doc that your are inserting is { action: 'task1', element: 'p', value: value_variable }
Because, you have this hook,
DisplayCol.before.insert(function (userId, doc) {
doc.userId = userId;
});
it changes the doc before inserting into collection. So the above hook will change your doc to {action: 'task1', element: 'p', value: value_variable, userId: 'actual-user-id' }
This is the expected behaviour.
Regarding your other point in the question,
userId is available to find and findOne queries that were invoked
within a publish function.
Previously userId parameter in the find and findOne returns null, so user needs to pass userId as a parameter as mentioned in this comment. Additional notes mentions that the hack is not required any more. It has nothing to do with inserting userId field into the collection document.
To have a quick test, remove the DisplayCol.before.insert hook above, you will not see userId field in the newly inserted documents.
UPDATE
Just to clarify your doubt further, from the 4th point in the docs that you provided
It is quite normal for userId to sometimes be unavailable to hook
callbacks in some circumstances. For example, if an update is fired
from the server with no user context, the server certainly won't be
able to provide any particular userId.
which means that if the document is inserted or updated on the server, there will be no user associated with the server, in that case, userId will return null.
Also you can check the source code yourself here. Check the CollectionHooks.getUserId method, it uses Meteor.userId() to get the userId.
CollectionHooks.getUserId = function getUserId() {
var userId;
if (Meteor.isClient) {
Tracker.nonreactive(function () {
userId = Meteor.userId && Meteor.userId(); // <------- It uses Meteor.userId() to get the current user's id
});
}
if (Meteor.isServer) {
try {
// Will throw an error unless within method call.
// Attempt to recover gracefully by catching:
userId = Meteor.userId && Meteor.userId(); // <------- It uses Meteor.userId() to get the current user's id
} catch (e) {}
if (!userId) {
// Get the userId if we are in a publish function.
userId = publishUserId.get();
}
}
return userId;
};
I have got problem accessing the user profile details of the users other then the current user.
The goal is to display a little footer under a each of the posts in the kind of blog entries list . Footer should consist of the post and author details (like date, username etc.).
Blog entry is identified by authors' _id but the point is that I can not access
Meteor.users.find({_id : authorId});
Resulting cursor seems to be the same as Meteor.user (not 'users') and consists of one only document, and is valid for the current user ID only. For others, like authors ID, I can only get an empty collection.
The question is, if is there any way, other then next Meteor.users subscription to get authors profile (like username profile.nick etc) ???
Update: You can Publish Composite package if you want to get blog entry and user details in a single subscription. See the following sample code and edit as per your collection schemas,
Meteor.publishComposite('blogEntries', function (blogEntryIds) {
return [{
find: function() {
return BlogEntries.find({ courseId: { $in: blogEntryIds }});
// you can also do -> return BlogEntries.find();
// or -> return BlogEntries.find({ courseId: blogEntryId });
},
children: [{
find: function(blogEntry) {
return Meteor.users.find({
id: blogEntry.authorId
}, {
fields: {
"profile": 1,
"emails": 1
}
});
}
}}
}]
});
End of update
You need to publish Meteor.users from the server to be able to use it on client. accounts package will publish current user, that's why you are only seeing current user's information.
In a file in server folder or in Meteor.isServer if block do something like this
//authorIds = ["authorId1", "authorId2];
Meteor.publish('authors', function (authorIds) {
return Meteor.users.find({ _id : { $in: authorIds }});
});
or
Meteor.publish('author', function (authorId) {
return Meteor.users.find({ _id : authorId });
});
Then on client side subscribe to this publication, in template's onCreated function, with something like this
Meteor.subscribe('author', authorId); //or Meteor.subscribe('author', authorIds);
or
template.subscribe('author', authorId); //or template.subscribe('author', authorIds);
If you want to show only username (or a few other fields), you can save them in post document along with authorId. For example:
post:{
...
authorId: someValue,
authorName: someValue
}
You can use them in your templates as a field of a post.
If you have too many fields which you do not want to embed in post document, (so you want to keep only authorId), you can use publish-composite when you make your posts publication. (See example 1)
You do not need to publish all your users and their profiles.
I have a simple todo schema: (just a sample to draw my question)
{
title: {
type: string
},
value: {
type: string
},
author: {
type: object
},
"author._id": {
type: string
},
"author.firstName": {
type: string
},
"author.lastName": {
type: string
},
}
The author entries are from meteor.user. If the meteor user changes the firstName or lastName i have to update the todo. I have two possibilities:
observerChanges (server side) to users collection and update all todos from this user with the new firstname/lastname
if i call the user update method i can call a method to update all todos
when it's better to use cursor.observeChanges and when it's better to call a update method manual? And why?
As the comment says, you should not store the author name / email in the document if it is mutable:
Store the ID of the user only in the document, the UserID is immutable.
When building your ToDo template, look up the User information by ID: you would need to publish a Publication for user by Id, and subscribe to it on the client with the userId as parameter.
Meteor.publish('userById', function(userId) {
return Meteor.users.find({_id: userId}, {limit:1});
});
in your route / template.onCreated depending on your Router, assuming the document is called doc
this.subscribe('userById', this.doc.author._id);
in the template helper
Template.todoTemplate.helpers({
'Author': function() {
return Meteor.users.findOne({_id: this.doc.author._id});
}
});
and call the Author info in the template
<Template name="todoTemplate">
First Name: {{Author.first_name}}
Last Name: {{Author.last_name}}
</Template>
I think you shouldn't rely on the second method, because sometimes you (or your teammate) might forget to update it. Moreover, if you're denormalizing user data in other collections, users knowing Meteor might just call your Meteor.method or manipulate db from the browser console...
You can use this package:
meteor add matb33:collection-hooks
It adds some hooks to your mongo insert/update/remove call
For example:
Meteor.users.after.update(function (userId, doc, fieldNames, modifier, options) {
if (this.previous.firstName === doc.firstName && this.previous.lastName === doc.lastName) {
return;
}
Todos.update({'author._id': doc._id}, {
$set: {
'author.firstName': doc.firstName,
'author.lastName': doc.lastName,
}
})
}, {fetchPrevious: true})
(To update the Todos collection efficiently, make sure to add index to author field)
This is just a handier way than writing your own observeChanges, and better than manually updating Todos collection every time you update the users collection, because you might forgot to call it in some case, or some hacker user just calls Meteor.users.update(Meteor.userId(), {...}) perhaps...
But still, I think you should always add some auto-correct mechanism to avoid wrong data being displayed, because no matter which method you choose, some error will occur (maybe the server watching the db just crashes right after users update). You can check on the client side when displaying content, if author.firstName doesn't match Meteor.users.findOne(author._id) (but you have to publish the user though...), than call a method to tell the server to update it.
I have a set of users defined like this:
Accounts.createUser({
username:'Simon',
email:'simon#email.com',
profile:{
firstname:'Simon',
lastname:'Surname',
location:'Home Address',
privacy: {
location:0,
emails:0 } //Location and emails are private and should not be disclosed
}
});
My question is how can I publish this user's record for other users to view, taking into account the profile privacy settings. In this example, I have set the privacy for location and emails to zero with the intention that this information is not published for this user.
I would like to publish it using the standard method:
Meteor.publish("usersWithPublicEmails", function () {
return Meteor.users.find();
});
But I cannot see a way to specify the selector or fields in such a way that only public information will be published.
I have tried adding additional publications of the form:
Meteor.publish("allUsers", function () {
return Meteor.users.find( {}, {fields:{username:1}} );
});
Meteor.publish("usersWithPublicEmails", function () {
return Meteor.users.find( {"profile.privacy.emails":1}, {fields:{username:1, emails:1}} );
});
but the selector does not seem to be returning the emails as I expected. I am looking for optimal way to do this from a performance point of view.
Mongodb is not a relational database so whenever I want to join or query based on metadata I remember I have to do things differently. In your case I would make a separate Collection for user privacy if I wanted to query on user privacy. In addition, if I cared about performance I probably would never want "all of x", I would just want enough to show the user, thus paginate. With these two ideas in mind you can easily get what you want: query based on privacy settings and performance.
Privacy = new Mongo.Collection("privacy");
Whenever we want to add privacy to an account:
Privacy.insert({
emails: 1,
userId: account._id,
});
Then later, one page at a time, showing ten results each page, tracking with currentPage:
Meteor.publish("usersWithPublicEmails function (currentPage) {
var results = []
var privacyResults = Privacy.find({"emails":1}, {skip: currentPage,
limit: 10});
var result;
while (privacyResults.hasNext() ) {
result = privacyResult.next();
results.append(Meteor.users.find({_id: result.userId});
}
return result;
});
I didn't test this code, it may have errors, but it should give you the general idea. The drawback here is that you have to keep privacy and users in sync, but these are the kinds of problems you run into when you're not using a relational database.
Mongodb has a way to do this kind of reference lookup with less code, but it still happens on demand and I prefer the flexibility of doing it myself. If you're interested take a look at Database references
That's because you have a typo in your publish function's fields object, instead of email you've typed emails
So the correct function would be:
Meteor.publish("usersWithPublicEmails", function () {
return Meteor.users.find( {"profile.privacy.emails":1}, {fields:{username:1, email:1}} );
});
Furthermore, you're already publishing all usernames in your allUsers publication, therefore, in order to add the missing data for relevant public users, you'll just need this:
Meteor.publish("usersWithPublicEmails", function () {
return Meteor.users.find( {"profile.privacy.emails":1}, {fields:{email:1}} );
});
and Meteor will automatically merge those records for you.
A simple solution in the end. I had missed the additional subscription in my router:
Router.route('/users', {
name: 'userList',
waitOn: function(){
return Meteor.subscribe('allUsers') &&
Meteor.subscribe('usersWithPublicEmails');
},
data: function(){
return Meteor.users.find();
}
});
A basic mistake:-(
I am saving logged in userId with each record saved in my Meteor app collection as shown in the example below, yet I was wondering if there was any way in Meteor where I can retrieve user name based on the user saved id without have to make another query on the users collection? In Node.js / mongoose there was this Populate function, but I can't seem to find similar package / function in Meteor. So I was wondering if someone can help me by suggesting a resolution to this problem (if any). thanks
var newInvoice = {
customerid: $(e.target).find('[name=customer]').val(),
userid: Meteor.userId(),
//....more fields here
}
Meteor.call('saveInvoice', newInvoice, function(error, id){
if(error)
return alert(error.reason);
});