Nest: Decorator for Cron Job and select by name on execution context

Created on 18 Apr 2018 · 6Comments · Source: nestjs/nest

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[ ] Regression 
[ ] Bug report
[x] Feature request
[ ] Documentation issue or request
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Current behavior

Resuming my case of use: I have a simple controller that GET /redirects, POST /redirects and POST /redirects/update.
This last one fetch an external URL and add to my database a list of redirects. Then, with my simple structure, I added a new decorator that I created.

@Post('/update')
@Cron('*/5 * * * * *')
update() {}

This Cron function is added to a list and after my app.listen I init and invoke the method update (or whatever I add the decorator).

The problem is, to call this update, I can do: this.app.select(RedirectsModule).get(RedirectsController).update();, but I can't run this by string name, only the component.

Expected behavior

What I need is that select and get accepts string, not the Module and Controller.

A workaround I found is to create an array like:

[
   { name: 'FooModule', module: FooModule },
   { name: 'BarModule', module: BarModule }
]

and search the .module based on .name. But I don't think it's the best to use.

Anyway, if anybody has a batter solution to add my "cron jobs", I would appreciate.

core discussion 🔥

Source

eliasjnior

Most helpful comment

Glad to hear! 🙂 v5.0.0 will hit final release very soon

kamilmysliwiec on 6 May 2018

👍3

All 6 comments

Well, looking deeper into the code, I found out some solutions. But this will need changes in the core, that I think it's nice to have.

I created a method decorator:

export const Cron = (period) => {
    return (target, paramName, descriptor) => {
        // Here I can add the descriptor to an array that I can access later. You will understand :P
        return descriptor;
    }
};

Then, after start the server with await app.listen(3000);, I have access to the app that returns me a INestApplication.

I looked into the code and saw that we have a property container, that has a method getModules(). So, I have to force the use of:

// Get the modules
const modules: ModulesContainer = app['container'].getModules();

That's not pretty, but the first thing I want to add is methods to access some part of this code, something like getContainer().

With this modules, I can loop in the list with modules.forEach(...) and check if the module is in my cron list, and call the method with (considering that I have methodName:

modules.routes.forEach(route => route.instance[methodName]());

So, I think we can add some things to make easier to access deeper in the code, so we can add more functionalities, like this Cron decorator that I'm looking for.

If I wasn't that clear, I try to explain in other way :P

eliasjnior on 23 Apr 2018

Hi @eliasjnior
Did you see https://github.com/OptimalBits/bull ?
it's The fastest, most reliable, Redis-based queue for Nodejs. _as said_

it also supports Scheduled and repeat jobs according to a cron specification.
so I think it will be suited here.
in fact, @fwoelffel created a Dynamic Module around it.
nest-bull, so it can be used in nest-ish way, _thanks Frédéric_ :smile: .

So back to the Monkey Patching :joy: that you did with nest container.
imo, it's very bad idea to get direct access to the container, as it was my idea at first :smile: see here #282

see also this pull #283 .
and now we have Dynamic Module so we can write our 3rd party module, did you checked out NestRouterModule it's a very good, simple example of how you could make your own dynamic modules that could be configured and change behavior as this this configuration .

Regards.