Utilizing this method can greatly enhance code readability and flexibility, but it requires a specific approach.
As mentioned by @Cohars, Sails expects controller actions to be functions. While you can't directly pass a generator like Koa, there are workarounds available. Essentially, a generator on its own is not very useful; you need a function to call and iterate it. Koa handles this at the framework level, but at the library level, options like co or yortus/asyncwait/ provide similar functionality. Personally, I prefer using yortus/asyncawait/ due to its flexibility with Node fibers being implemented as functions compared to ES6 generators.
Here's how to implement it:
Start by running npm install co and require it in your controller or add it globally in config/bootstrap.js for frequent use. Once setup is complete, integrate it into your controllers.
module.exports = {
hi: function(req, res){
co(function* (){
// You can incorporate it with model calls like this
let user = yield User.findOne(req.param('id'))
return res.send("Hello " + user.name + "!");
})
}
};
That's the basic implementation.
If you prefer using async/await, the process is quite similar:
module.exports = {
hi: function(req, res){
async(function(){
let userName = await(User.findOne(req.param('id'))).name
return res.send("Hi there " + userName + "!");
})();
}
};
A point to note is that when calling other methods of your controller using this, ensure to preserve the context since it will reference the generator function, or the regular function if you're utilizing async/await. Using fat arrows with async/await can help maintain contexts efficiently.
I've been utilizing the second approach for several months now, finding success with both methods. The async/await module appears slightly faster and aligns well with CoffeeScript usage.
UPDATE:
An async-handler wrapper has been developed to complement yortus async/await functionality. Feel free to modify it for compatibility with other libraries if needed.
You can access the wrapper at https://www.npmjs.com/package/async-handler. It's currently in alpha, but I've tested it in my applications with positive results. Should you encounter any issues, kindly submit them for resolution.
With the async-handler in place, errors related to async/promise handling propagate correctly within Sails unless caught by a try/catch block.