Fetch associations for an array of models when `autoFetch` is off (similar to Mongoose's `populate`) ?

[cheapsteak]

I have two models with a many to many relationship, routes and stops (for buses)

given an api like below:

/routes   
/routes/12,13,22,555,103,23,19/stops  
/stops   
/stops/23,32/routes   

I don't want /routes nor /stops to autoload, there's too much data, but I do want /routes/:ids/stops to autoload, and same for /stops/:ids/routes.

Is this possible?

Also, what's a way to do it without using autoload?
I've gotten this far:

app.get( '/api/routes/:ids/stops', function (request, response){
    var ids = request.params.ids.split(',');
    return request.models.route
        .find({id: ids})
        .each(function (route) {
            route.getStops(function(err, stops){ 
                route.stops = stops; // <--- need to make sure this gets called before returning
            });
        })
        .get(function(routes) {
            return response.send( routes );
        });
});

but I'm currently stuck trying to figure out how to make sure all the route.getStops have returned before sending the response.

Would I need a promise library to deal with this?

---

edit: dug around the source, found this but I don't seem to be using it correctly

request.models.route.settings.set('instance.autoFetch', true);
request.models.stop.settings.set('instance.autoFetch', true);

setting this doesn't seem to affect anything

---

edit: setting it as an option passed to find doesn't seem to work either

return request.models.route.find({id: ids}, {autoFetch: true}, function(err, routes){
    return response.send( routes );
});

---

edit: ~~~possibly solved?~~~ (nvm, apparently this messes up caching)
changed line 245 of Model.js from

autoFetch      : (options.autoFetchLimit === 0 ? false : opts.autoFetch)

to

autoFetch      : (options.autoFetchLimit === 0 ? false : options.autoFetch)

to allow specifying autoFetch as an option when calling find.

was this a typo or was the autoFetch not intended to be override-able?

---

edit: apparently changing that messes up caching.

request.models.route.find({id: ids}, {autoFetch: false})

or

request.models.route.find({id: ids}, {autoFetch: true})

whichever one gets called first ends up determining autoFetch forever.

setting instance settings via request.models.model.settings.set didn't work either

app.get( '/api/routes/:ids', function (request, response){
    request.models.route.settings.set('instance.autoFetch', false); 
    request.models.route.find({id: ids}, {autoFetch: false})
}

app.get( '/api/routes/:ids/stops', function (request, response){
    request.models.route.settings.set('instance.autoFetch', true);
    request.models.route.find({id: ids}, {autoFetch: true})
});

The setting does change but it doesn't seem to affect the output

[dresende]

I'm sorry for not replying earlier but I'm a little short in time. I have to take some time to test more properly before answering you.

[dresende]

It seems there is some trouble with passing autoFetch to Model.find. I'm going to make some tests and fix this.

[dresende]

This fix doesn't magically solve your problem. I would advise you to do this way:

1. Don't enable autoFetch on Model definition, keep cache enabled (default);
2. When just wanting to fetch a Route info or Stop info, just go on and do Model.find(). It shouldn't fetch the association items and that's what you want;
3. When you need to fetch a Route and related Stops (or vice-versa), use Model.find(..., { cache: false, autoFetch: true }).

[cheapsteak]

Yup, that works great, thanks!
How big of a deal is caching? Would it be a good idea to try to implement separate instances depending on whether 'autoFetch' is on, or is that going to open up a can of worms?

[dresende]

Yeah, that might open the can, I have to think a bit more about the cache keys.