sails many to many associations failing to save - save

Question

My sails many to many associations have stopped saving changes, that is, if I deselect one of the items in my checkbox list, or select a new one, the changes are not saved (populated to the join table).
It used to work, although I am not sure how long it's been broken for.
All the other fields on the page save correctly.
So I know the mechanics of most of it are correct, just the many to many associations, ie, updating the list of active records in the join table.
Any hints on what I can be doing wrong in my save?
I have the following models:
/**
* User.js
*/
module.exports = {
attributes: {
projects: {
collection: 'project',
via: 'users'
},
}
/**
* Project.js
*/
module.exports = {
attributes: {
users: {
collection: 'user',
via: 'projects',
dominant: true
},
}
In my form I am returning a checkbox list like such
{ projectname: 'AS Story Database',
userlist: [ '10', '3', '1' ], <-- this line is the many to many line from the check boxs
projecttype: 'Development',
companyid: '1',
startdate: 'Sat Jan 01 2011 00:00:00 GMT+1100 (AUS Eastern Daylight Time)',
enddate: '' }
}
I tried populating the result set
Project.findOne({'id':id})
.populate('users') <--------- heres the populate I added but didnt seem to have effect
.exec(function(err,project){
This is the save dialog in my sails controller
var a=req.param('project',null);
console.log(a); <-- note this is where the json above is output
project.projecttype= a.projecttype,
project.projectname= a.projectname,
project.companyid= a.companyid,
project.users= a.userlist, <-- this is the many to many association that used to work
project.startdate = a.startdate,
project.enddate = a.enddate
project.save(function(err,updated){ <-- here is the save function
if (err) {
req.session.flash = {'err':err};
sails.controllers.project.edit(req,res);
}else{
req.session.flash = {};
res.redirect('project/index');
}
});

Answer 1

#Sangharsh is correct in his comment above; you cannot update a collection by assigning an array to it and calling .save(). You may be thinking of .update(), which in Sails v0.12.x allows you to provide an array of objects to replace the existing set (although this has been removed in Sails 1.0 since it caused a lot of bugs and confusion).
The correct way to update an existing instance's collection in Sails v0.12.x is to use the .add() and .remove() methods. See the many-to-many associations doc page for more info.
In Sails 1.0, the .save() method of individual records has been removed to make things clearer; you always use the .addToCollection(), .removeFromCollection() and .replaceCollection() model class methods to manipulate plural associations.

Answer 2

Ok; I finally figured this out.
The method above (replaceCollection) only works on the older (0.x) versions of sails.
To get it working in the modern version, use
<model>.update('id':<the recordID>},{'<association name>':<list of new records>})
.exec(function(err,updated){
-do something-
});
ie -
Project.update({'id':id},{'users': a.userlist}).exec(function(err,updated){
project.save(function(err,updated){
//console.log(updated);
if (err) {
console.log(err);
req.session.flash = {'err':err};
sails.controllers.project.edit(req,res);
}else{
req.session.flash = {};
res.redirect('project/index');
};
});
});