serverMiddleware 访问 Nuxt 实例或上下文

Question

im trying to access Nuxt runtime variables from a serverMiddleware

Example i have this context.$db which i added from this plugin

nuxt.config.js :

    plugins: [
        { src: '~/plugins/db_runtime.js', mode: 'server' }
    ]

~/plugins/db_runtime.js :

    db = 'test'
    
    export default ({ app }, inject) => {
        inject('db', db)
    }

Then i added a serverMiddleware:

    serverMiddleware: [
        { path: '/api', handler: '~/api/index.js' },
    ],

The serverMiddleware: ~/api/index.js :

    export default function(res, req) {
    }

Is there anyway to access context.$db from there? ie

    export default function(res, req) {
        $config.db = null
    }

Answer 1

For static data, what i usually did is using either environment variables (.env) or modules declared in nuxt.config.js to pass the data.

For dynamic data, since serverMiddleware is always invoked in the same lifecycle of your nuxt app, you can safely send the data as HTTP request using asyncData() or fetch() or axios

Please refer to the following link/diagram for serverMiddle lifecycle:

Understanding modules, serverMiddleware and plugins in Nuxt.js configuration

Answer 2

So I'm not 100% versed in the Nuxt lifecycle (v2.x), but afaik you CANNOT access the Nuxt app context during the serverMiddleware lifecycle phase. serverMiddleware is really connect -based (used internally by Express, btw) for processing req , res and next parameters, which represent the request, the response, and next which is connect s flow management parameter.

The basic conceptual reason is that the Nuxt app context supports both the server and client-side, and the default 'universal' mode is a core objective of Nuxt. connect is really a server-side only library designed to handle the request and response nature of an application server.

Since you need config.$db , provided the configuration values you need are static, there may be an alternative way to use the nuxt.config env and the general environment variables in serverMiddleware . $config is a newer Nuxt construct intended to allow more flexible runtime environment variables (as well as normal env vars).

Here is the current 2.x link to the middleware vs serverMiddleware explanation provided by Nuxt. I've also cut/paste the text info in case the link on Nuxt decays.

serverMiddleware vs middleware!

Don't confuse it with routes middleware which are called before each route by Vue in Client Side or SSR. Middleware listed in the serverMiddleware property runs server-side before vue-server-renderer and can be used for server specific tasks like handling API requests or serving assets.

Do not add serverMiddleware to the middleware/ directory.

Middleware, are bundled by webpack into your production bundle and run on beforeRouteEnter. If you add serverMiddleware to the middleware/ directory it will be wrongly picked up by Nuxt as middleware and will add wrong dependencies to your bundle or generate errors.

Btw, as always, if I'm incorrect on any of the above, I'm always appreciative of Stackflow users who point out what is wrong or can be explained better