realFetch.call is not a function

[jamespedid]

TypeError: realFetch.call is not a function
       at fetch (/usr/lib/leaguegamer/webserver/build/webpack:/datalibrary/node_modules/cross-fetch/dist/node-ponyfill.js:9:1)

When I inspect the import using the developer tools, the realFetch is an object, and not a function. On this object, there is the fetch function.

I'm unsure if this is a problem with the library or some kind of weird artifact that I have with the build. It would seem to be the latter, but I can't track it down. Any idea why require('node-fetch') is returning an object?

[lquixada]

that's strange. maybe node-fetch is not properly installed on your node_module. go to the /datalibrary/ and run node -p "require('node-fetch')". What's the output?

[jamespedid]

I actually figured it out last night. It had to do with the way webpack was building the file. (I use webpack on the server-side too.) It was having trouble loading node-fetch in the right way. I was able to add node-fetch to the list of excludes and it solved the problem.

If anyone else has a problem like this, then this will remain here for troubleshooting.

[alexvetter]

Hi @lquixada,
Hi @jamespedid,

I'm currently facing the same issue. I upgraded from cross-fetch@1.1.1 to cross-fetch@2.2.0. After the upgrade I got the runtime error TypeError: realFetch.call is not a function.

I'm using cross-fetch in a webpack-bundled TypeScript backend.

If I change the require to require('node-fetch').default in ./node_modules/cross-fetch/dist/node-ponyfill.js it works like a charm.
If I import node-fetch instead of cross-fetch it also works.

Looks like others have kinda the same problem with node-fetch (node-fetch/node-fetch#450).

But I'm not sure how to fix this in our code. Perhaps it has something to do with your rollup build?

[lquixada]

Hi @alexvetter! I've identified the issue. The newer node-fetch version has two entry-points: main and module. When you require node files (without a bundler), it uses main. When you require bundled file (with target: node), it uses module.

The module entry point uses es modules, thus the "default" property works. I'm already working on a solution.

[alexvetter]

Thank you very much! I would hoped I could have been of more value for fixing that issue. Really appreciate your fast response!

[lquixada]

no problem! btw, can you do npm install lquixada/cross-fetch in your project and make sure the patch worked?

[alexvetter]

I should have been more clear. Yes, it works! Thanks again. Looking forward to a official release.