应该是小写的accept

[Shylock]

nestjs-course-code/custom-decorator/src/my.decorator.ts

Line 7 in 556bb97

 return key ? request.headers[key] : request.headers; 

通过const request: Request = ctx.switchToHttp().getRequest();拿到的request中的属性都变成小写了

所以应该是

return key ? request.headers[key.toLocaleLowerCase()] : request.headers;