Extending with Middlewares

Whereas HttpServerShim provides many default request pre and post handlers, you may want to add your own custom middleware to control body-parsing or header-parsing behavior in a globel level. Such server-wide middleware support is provided by HttpServerShim.addMiddleware(handler).

export class MyAppServer extends HttpServerShim {
    ...
}

server.addMiddleware(async (op) => {
    op.oriReq // you can access original request object from Express of Fastify
    op.oriRes // you can access original response object from Express of Fastify

    // no need for `next()` as `op` object will be passed to APIs
})

Custom `pre` and `post` Handlers

In HttpServerShim terms, pre handler runs during request reception, and post handler runs after op object returns. You can individually override the pre and post behavior of a standalone httpOp by providing callbacks config at the op definition

import { HttpServerShim, httpOp, httpParam, httpReturn, required } from 'ts-basis/nodejs'

export class MyAppServer extends HttpServerShim {
    ...
    async initialize() {
        ...
        // Preprocessors (e.g. JSON body-parsing)
        this.addDefaultProcessor(
            ReqProcessor.AUTH, // checks token in Authorization header if custom handler is not defined
            ReqProcessor.BASIC, // auto-parses body to JSON; much like json-parse middleware
        )
    }
}

server.addMiddleware(async (op) => {
    ...
})

// Define standalone server operation with well-known input/output
export const myApiFunction = httpOp(
    {
        params: {},
        callbacks: {
            onBeforePre: (op) => {
                // runs before pre-processing
            },
            onAfterPre: (op) => {
                // runs after pre-processing
            },
            onBeforePost: (op) => {
                // runs before post-processing
            },
            onAfterPost: (op) => {
                // runs after post-processing
            },
        },
        returns: httpReturn<{ data: string }>(),
    },
    async (op) => {
        return op.returnJson({ data: 'Hello World!' })

        // ==== Order of Processing ====
        //
        // custom middlewares (addMiddleware)
        // onBeforePre
        // ReqProcessor.AUTH
        // ReqProcessor.BASIC (json parser)
        // onAfterPre
        // this function: async (op) => {
        //     return op.returnJson({ data: 'Hello World!' })    
        // }
        // onBeforePost
        // Post-processing
        // onAfterPost
        //
    },
)

Custom pre and post Handlers​

Custom `pre` and `post` Handlers