Result Class — supabase Architecture

Source Code

apps/docs/features/helpers.fn.ts lines 34–186

export class Result<Ok, Error> {
  constructor(private internal: { data: Ok; error: null } | { data: null; error: Error }) {}

  static ok<Error = unknown, Ok = unknown>(data: Ok): Result<Ok, Error> {
    return new Result<Ok, Error>({ data, error: null })
  }

  static error<Ok = unknown, Error = unknown>(error: Error): Result<Ok, Error> {
    return new Result<Ok, Error>({ data: null, error })
  }

  static tryCatchSync<Ok, Error, Args extends Array<unknown>>(
    fn: (...args: Args) => Ok,
    onError: (error: unknown) => Error,
    ...args: Args
  ): Result<Ok, Error> {
    try {
      return Result.ok(fn(...args))
    } catch (error: unknown) {
      return Result.error(onError(error))
    }
  }

  static async tryCatch<Ok, Error, Args extends Array<unknown>>(
    fn: (...args: Args) => Promise<Ok>,
    onError: (error: unknown) => Error,
    ...args: Args
  ): Promise<Result<Ok, Error>> {
    try {
      return Result.ok(await fn(...args))
    } catch (error: unknown) {
      return Result.error(onError(error))
    }
  }

  static async tryCatchFlat<
    Ok,
    Args extends Array<unknown> = [],
    OuterError = unknown,
    InnerError = unknown,
  >(
    fn: (...args: Args) => Promise<Result<Ok, InnerError>>,
    onError: (error: unknown) => OuterError | InnerError,
    ...args: Args
  ): Promise<Result<Ok, OuterError | InnerError>> {
    try {
      return await fn(...args)
    } catch (error: unknown) {
      return Result.error(onError(error))
    }
  }

  static transposeArray<Ok, Error>(
    array: Array<Result<Ok, Error>>
  ): Result<Array<Ok>, MultiError<Error>> {
    let data: Array<Ok> = new Array(array.length)
    let error: MultiError | null = null

    for (const result of array) {
      if (result.isOk()) {
        data.push(result.internal.data!)
      } else {
        ;(error ??= new MultiError('MultiError:')).appendError(
          extractMessageFromAnyError(error),
          result.internal.error
        )
      }
    }

    if (error) return Result.error(error)
    return Result.ok(data)
  }

  isOk(): this is Result<Ok, never> {
    return this.internal.error == null
  }

  map<Mapped>(fn: (data: Ok) => Mapped): Result<Mapped, Error> {
    if (this.isOk()) return Result.ok(fn(this.internal.data!))
    return this as unknown as Result<Mapped, Error>
  }

  async mapAsync<Mapped>(fn: (data: Ok) => Promise<Mapped>): Promise<Result<Mapped, Error>> {
    if (this.isOk()) return Result.ok(await fn(this.internal.data!))
    return this as unknown as Result<Mapped, Error>
  }

  mapError<MappedError>(fn: (error: Error) => MappedError): Result<Ok, MappedError> {
    if (this.isOk()) return this as unknown as Result<Ok, MappedError>
    return Result.error(fn(this.internal.error!))
  }

  flatMap<Mapped>(fn: (data: Ok) => Result<Mapped, Error>): Result<Mapped, Error> {
    if (this.isOk()) return fn(this.internal.data!)
    return this as unknown as Result<Mapped, Error>
  }

  flatMapAsync<Mapped>(
    fn: (data: Ok) => Promise<Result<Mapped, Error>>
  ): Promise<Result<Mapped, Error>> {
    if (this.isOk()) return fn(this.internal.data!)
    return Promise.resolve(this as unknown as Result<Mapped, Error>)
  }

  match<Mapped, MappedError>(
    onOk: (data: Ok) => Mapped,
    onError: (error: Error) => MappedError
  ): Mapped | MappedError {
    if (this.isOk()) return onOk(this.internal.data!)
    return onError(this.internal.error!)
  }

  unwrap(): Ok {
    if (!this.isOk()) {
      throw new Error(`Unwrap called on Err: ${this.internal.error}`, {
        cause: this.internal.error,
      })
    }
    return this.internal.data!
  }

  unwrapOr(deflt: () => Ok): Ok {
    if (this.isOk()) return this.internal.data!
    return deflt()
  }

  unwrapError(): Error {
    if (this.isOk()) {
      throw new Error(`UnwrapError called on Ok`)
    }
    return this.internal.error!
  }

  unwrapErrorSafe(): Error | null {
    return this.internal.error
  }

  unwrapEither(): Ok | Error {
    if (this.isOk()) return this.unwrap()
    return this.unwrapError()
  }

  join<OtherOk, OtherError>(
    other: Result<OtherOk, OtherError>
  ): Result<[Ok, OtherOk], [Error, OtherError]> {
    if (!this.isOk() || !other.isOk())
      return Result.error([this.internal.error, other.internal.error]) as Result<
        [Ok, OtherOk],
        [Error, OtherError]
      >
    return Result.ok([this.internal.data!, other.internal.data!])
  }
}