#4479·hapi

[TS] Defining the handler and the return type

Author: jaclasCreated Feb 7, 2024Updated Jun 9, 2024

Labelssupport

Runtime

Node

Runtime version

Module version

21.3.3

Used with

standalone

Any other relevant information

No response

How can we help?

I would like the handler to explicitly return the DataResultObject type (my object type), the handler type declaration in Hapi looks like this:

javascript

export namespace Lifecycle {
    /**
     * Lifecycle methods are the interface between the framework and the application. Many of the request lifecycle steps:
     * extensions, authentication, handlers, pre-handler methods, and failAction function values are lifecycle methods
     * provided by the developer and executed by the framework.
     * Each lifecycle method is a function with the signature await function(request, h, [err]) where:
     * * request - the request object.
     * * h - the response toolkit the handler must call to set a response and return control back to the framework.
     * * err - an error object available only when the method is used as a failAction value.
     */
    type Method<
        Refs extends ReqRef = ReqRefDefaults,
        R extends ReturnValue<any> = ReturnValue<Refs>
    > = (
            this: MergeRefs<Refs>['Bind'],
            request: Request<Refs>,
            h: ResponseToolkit<Refs>,
            err?: Error | undefined
        ) => R;

So I declare the route object like this:

typescript

const poemsRoutings: ServerRoute<ReqRefDefaults, DataResultsObject>[] = [
    {
        method: "GET",
        path: "/api/poems/pages/count",
        options: {
            handler: poems.getPoemsPagesCountHandler,
            auth: {
                mode: "try"
            }
        }
    },

and the environment (vscode) correctly develops this type, showing that my type will be returned:

But at the same time, I get a TS compilation error (which you can also see in the screenshot) that reads:

Generic type 'ServerRoute<Refs>' requires between 0 and 1 type arguments.ts(2707)

How to do this correctly?

Source: hapijs/hapi

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