Ncc: @now/node error: Cannot find module 'pug'

[coetry]

When using the stable or canary builder, express deployments that depend on pug will run into the following error: Error: Cannot find module 'pug'

To reproduce this issue, I made a repo that you can clone and deploy: https://github.com/coetry/wtf-pug

Note that i've included a test-server.js file, which works fine locally. Also note that this is not an ncc error because if you run ncc build index.js && cp test-server.js dist && cd dist && node test-server.js, it will work as expected. This error is only encountered when deploying.

[styfle]

@guybedford I was able to reproduce this issue.

Steps to reproduce

git clone https://github.com/coetry/wtf-pug
cd wtf-pug
npm install
ncc build test-server.js
rm -rf node_modules # this step is important
node dist/index.js

Error

When you visit http://localhost:3000 you'll see the following error

Error: Cannot find module 'pug'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:582:15)
    at Function.Module._load (internal/modules/cjs/loader.js:508:25)
    at Module.require (internal/modules/cjs/loader.js:637:17)
    at require (internal/modules/cjs/helpers.js:22:18)
    at new View (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:16535:14)
    at Function.render (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:3765:12)
    at ServerResponse.render (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:13687:7)
    at module.exports.318.app.get (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:6966:7)
    at Layer.handle [as handle_request] (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:3942:5)
    at next (/Users/styfle/Desktop/foobar/wtf-pug/dist/index.js:14058:13)

Workaround

There is a workaround to get this to work as expected thanks to @TooTallNate 🙌

Our users would never think about this solution so it's a hack to get around the dynamic require.

--- a/index.js
+++ b/index.js
@@ -3,6 +3,7 @@ const path = require("path");

 const app = express();

+app.engine("pug", require("pug").__express);
 app.set("view engine", "pug");
 app.set("views", path.join(__dirname, "views"));

@guybedford Is this fixable? (related to #254)

[guybedford]

The fix here sounds exactly right to me.

The only alternative we have would be to explicitly support this ExpressJS usage pattern that is:

• If there is a require to "express"
• And that require is called as a function and assigned to another variable
• And that instance has app.set("view engine", ...) called, then include the line app.engine("pug", require("pug").__express);

This would be a bit of work to integrate and would be only for this use case, but it would be possible to ensure this exact use case is fixed.

[styfle]

@guybedford Let's solve this for all express templates.

Since express expects the default export to be __express from the template, I think it can be fixed for all template engines, not just pug.

Express is probably the most popular node.js http framework so we need to have this working in ncc.

[coetry]

I agree, solving this for all express template engines would be ideal.

[guybedford]

Fix created in https://github.com/zeit/webpack-asset-relocator-loader/pull/11.