Dependency loading issue in canary with Experimental API Support

I am trying out the canary build with the experimental API support https://github.com/zeit/next.js/pull/7296.

I am using Mongoose as my ORM and when I try load a schema from the /pages/api/product.js like

const Category = require('../../models/category')
export default async (req,res) => {
  const data = Category.find{...}
 res.json(data)
}

I am getting this error

{ OverwriteModelError: Cannot overwrite `Category` model once compiled.
    at new OverwriteModelError (/Users/rameshvel/work/dailybasket/node_modules/mongoose/lib/error/overwriteModel.js:20:11)
    at Mongoose.model (/Users/rameshvel/work/dailybasket/node_modules/mongoose/lib/index.js:423:13)
    at Object../models/category.js (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:142:27)
    at __webpack_require__ (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:23:31)
    at Module../pages/api/category.js (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:498:16)
    at __webpack_require__ (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:23:31)
    at Object.3 (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:605:18)
    at __webpack_require__ (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:23:31)
    at /Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:91:18
    at Object.<anonymous> (/Users/rameshvel/work/dailybasket/.next/server/static/development/pages/api/category.js:94:10)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:20:18)
    at DevServer.handleApiRequest (/Users/rameshvel/work/dailybasket/node_modules/next-server/dist/server/next-server.js:180:59)
  message: 'Cannot overwrite `Category` model once compiled.',
  name: 'OverwriteModelError' }
[ event ] disposing inactive page(s): /api/category
[ ready ] compiled successfully

If I comment out the mongoose model loading and just return any random json it works fine.

System information

• OS: macOS
• Version of Next.js: [Latest Canary]

Seems something is forcing to recreate the mongoose model. any ideas?

[johnbarhorst]

I ran into this same issue today, with next v- 9.5.2. New to next, it took me a bit to stumble on this solution. Ultimately it looks like making sure I’m consistent with using import statements, instead of copy paste my old require syntax from old mongo files fixed a lot of things. In case anyone else has a head v wall day like I did today. Also an npm rebuild was thrown in with a server restart.

[joshleblanc]

Instead of exporting the mongoose.model(‘Category’, schema), try requiring the file and using mongoose.Model('Category') to use the model. It kind of seems like next is running the import twice and trying to re-create the Category model.