[Vapor4] Creating custom asynchronous external API

Hello, everyone. I'm Vapor beginner.

I'm interested in Vapor 4 recently, started to make a toy project with it.
But having trouble with few things. Please help out if you have some ideas on it.

Here's what I want to create ;

  1. Define POST routes with one parameters.

  2. Asyncronous job with 3rd party library.

  3. Save to Database

func createHandler(_ req: Request) throws -> EventLoopFuture<CustomModel> {
     // 1.
     let param = try req.content.decode(ParamModel.self)
    // 2. Asyncronous
    ThirdPartyLibrary.request(with: param) { result in
          // 3. How to save model and return EventLoopFuture
         let saveModel = CustomModel(title: result.title,
                                     description: result.description)

         saveModel.save(on: req.db)

I found external API like this..


However, it is confused with the previous case.

Any idea how I can make this work?

Thank you.

Presumably, your third-party library does not return an EventLoopFuture and is just a 'normal' completion handler API. In that case, you need to bridge the two worlds by making a EventLoopPromise which is resolved in the body of the completion block. The NIO docs has a nice example of the pattern.

If you need to call this closure API many times, you can make an extension that is implemented with a promise, but only expose a future-based API to the rest of your project.

Hi, @bzamayo
Thanks for the reply.
I will study more with the information you informed.

Thank you! :pray: