Use AdminJS with Nuxt/H3

route.ts

// server/routes/admin/[...].ts
// server/routes/admin/index.ts

import { adminRouter } from '~~/server/admin/router';

export default useBase('/admin', adminRouter.handler);

router.ts

// server/admin/router.ts

import { adminApp } from '~~/server/admin';
import { Router as AdminRouter } from "adminjs";
import { getRouterParams, type Router, sendStream } from 'h3';
import { readFiles } from 'h3-formidable';
import path from 'node:path';
import { createReadStream } from 'node:fs';

const checkAuthentication = (event: any) => {
    return { email: 'abc' };
}

const buildRoute = ({ route, router }: {
    route: (typeof AdminRouter)["routes"][number];
    router: Router;
}) => {
    router.add(
        route.path.replace(/{/g, ":").replace(/}/g, ""),
        eventHandler(async event => {
            const auth = checkAuthentication(event);
            if (!auth) {
                throw createError({
                    statusCode: 401,
                    statusMessage: 'Unauthorized',
                });
            }
            const controller = new route.Controller({ admin: adminApp }, auth);

            const query = getQuery(event);
            const params = getRouterParams(event);
            const method = event.method.toLowerCase();
            const { fields, files } = await readFiles(event);
            const payload = {
                ...(fields || {}),
                ...(files || {}),
            };
            const html = await controller[route.action](
                {
                    ...event.node.req,
                    params,
                    query,
                    payload,
                    method,
                },
                event.node.res,
            );
            if (route.contentType) {
                event.node.res.setHeader('Content-Type', route.contentType);
            }
            if (html) {
                return html;
            }
            return null;
        }),
        route.method.toLowerCase() as 'get' | 'post',);
}

const buildRouter = () => {
    const { routes, assets } = AdminRouter;

    const router = createRouter();

    const componentBundlerRoute = routes.find(
        r => r.action === "bundleComponents"
    );
    if (componentBundlerRoute) {
        buildRoute({ route: componentBundlerRoute, router });
    }

    assets.forEach((asset) => {
        router.get(
            asset.path,
            eventHandler(event => {
                let mimeType = undefined;
                if (asset.path.endsWith('.js')) {
                    mimeType = 'application/javascript';
                } else if (asset.path.endsWith('.css')) {
                    mimeType = 'text/css';
                }
                if (mimeType) {
                    event.node.res.setHeader('Content-Type', mimeType);
                }
                return sendStream(event, createReadStream(path.resolve(asset.src)))
            })
        );
    });

    routes.forEach(route => {
        buildRoute({ route, router })
    })

    return router;
}

export const adminRouter = buildRouter();