Class identifiers is unique but still getting error.

[mdragoss]

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@JsonObject('City') // Make sure "City" is a unique identifier for this class export class City {}

Get an error Error: Fatal error in JsonConvert. You must use unique class identifiers in the @JsonObject() decorator. Class identifier: City

 "next": "12.2.5",
 "react": "18.2.0",
 "react-dom": "18.2.0",
 "typescript": "4.7.4"

[andreas-aeschlimann]

Can you provide a minimal example in a Stackblitz?

I don't think it is possible to get this error with a class definition like above, unless you have a conflict of multiple class names.

[mdragoss]

Hello, here is example, can be made some changes after saving getting error. https://stackblitz.com/edit/nextjs-9n54xo?file=pages/index.tsx

[andreas-aeschlimann]

I don't know what's going on under the hood with nextjs, but the problem seems that your file hello.ts is loaded twice in this application. I was able to verify this fact by adding a console.log into this file. Thus, the class City is read twice and json2typescript throws the error about not having a unique class City.

If you manage to work around this duplicate loading, you will fix the error.

[mdragoss]

Ok, thanks, I should try to play with reactStrictMode enable and disable in next js config.