Cannot determine GraphQL output type

[repomaa]

I found several issues referencing this error and they made me think it has to be an issue with using babel instead of "real" transpiling with tsc so i went and extracted my type-graphql api, which was part of a nextjs project (thus babel). Compiling it with tsc and running the resulting javascript still gives me the same error. I've been debugging this for 8 hours straight now but have gotten nowhere. I hope you can help me out! <3

So the concrete error that occurs when the schema is built is this:

(node:1304860) UnhandledPromiseRejectionWarning: Error: Cannot determine GraphQL output type for 'content' of 'Page' class. Is the value, that is used as its TS type or explicit type, decorated with a proper decorator or is it a proper output value?
    at Function.getGraphQLOutputType (/.../demo/node_modules/type-graphql/dist/schema/schema-generator.js:519:19)
    at /.../demo/node_modules/type-graphql/dist/schema/schema-generator.js:175:47
    at Array.reduce (<anonymous>)
    at fields (/.../demo/node_modules/type-graphql/dist/schema/schema-generator.js:166:53)
    at resolveThunk (/.../demo/node_modules/graphql/type/definition.js:480:40)
    at defineFieldMap (/.../demo/node_modules/graphql/type/definition.js:692:18)
    at GraphQLObjectType.getFields (/.../demo/node_modules/graphql/type/definition.js:633:27)
    at collectReferencedTypes (/.../demo/node_modules/graphql/type/schema.js:366:81)
    at collectReferencedTypes (/.../demo/node_modules/graphql/type/schema.js:368:9)
    at new GraphQLSchema (/.../demo/node_modules/graphql/type/schema.js:153:7)

Here's a minimal project which demonstrates the issue.

https://p.jokke.space/5IT/

[MichalLytek]

TAR file? Really? On a GitHub?

Please make a proper github repository for me to browse the code, or just paste a snippet with the Page class file.

[repomaa]

Alright, sure. Was just the fastest way for me. Anyway, here you go: https://github.com/repomaa/type-graphql-demo

[MichalLytek]

Missing decorator call @ in src/graphql/schema/page/bard/content.ts

[repomaa]

OMG! Thank you so much! I was secretly hoping it would be something so trivial! Saved my day! I have to get used to decorators i guess. There's no way to make a function only work as a decorator, right?

[MichalLytek]

No, decorators are functions that are called with class metadata. It happens during the TS transpilation process.