Unable to infer GraphQL type from TypeScript reflection system

Question

I'm trying to create an Alert class as follows:

@ObjectType()
export class Alert {
  @Field()
  status: 'error' | 'success' | 'warning' | 'info' | undefined

  @Field(() => [String])
  messages: string[];
}

However, it gives me the following error message:

Error: Unable to infer GraphQL type from TypeScript reflection system. You need to provide explicit type for 'status' of 'Alert' class.

Answer 1

Create a type for 'error' | 'success' | 'warning' | 'info' | undefined 'error' | 'success' | 'warning' | 'info' | undefined 'error' | 'success' | 'warning' | 'info' | undefined and add it to the field definition as such: @Field(() => StatusType)

It's basically complaining that it can't infer the type of that field as it's not a primitive, whenever a field is an object or other user defined type you will need to provide type information like I've described

Answer 2

my work around for the problem was an enum and tuple type.

//anything after EnumStatus is optional. depends on how much control you want.
type TSuccessArray = [EnumStatus.ERROR, EnumStatus.SUCCESS,EnumStatus.WARNING,EnumStatus.INFO,EnumStatus.UNDEFINED]

export enum EnumStatus {
        ERROR = "error",
        SUCCESS = 'success',
        WARNING = 'warning',
        INFO = "info",
        UNDEFINED = "undefined"
      }

    @ObjectType()
export class Alert {
  @Field(() => [String])
  status: TSuccessArray[];

  @Field(() => [String])
  messages: string[];
}

and somewhere in your code create a table or object with those options.

`const myArr:succesArray = [EnumStatus.ERROR, EnumStatus.SUCCESS,EnumStatus.WARNING,EnumStatus.INFO,EnumStatus.UNDEFINED]`;

Answer 3

You can try adding this to your tsconfig.json file

"experimentalDecorators": true,
"emitDecoratorMetadata": true,