Should redirect send an error?

[hiroki0525]

Goals

Developer Experiences: When using redirect, it must be determined whether an Error or a non Error object is thrown.

Background

First, Suppose that such a function has been defined.

import { InferOutput, object, ObjectEntries, safeParse } from 'valibot';

export type FormActionState = {
  isError: boolean;
  message: string;
};

type GenerateFormActionParams<T extends ObjectEntries> = {
  shema: ReturnType<typeof object<T>>;
  onValid: (output: InferOutput<ReturnType<typeof object<T>>>) => Promise<FormActionState> | never;
};

export const generateFormAction =
  <T extends ObjectEntries>(params: GenerateFormActionParams<T>) =>
  async (
    _prevState: FormActionState | null,
    formData: FormData,
  ): Promise<FormActionState | null> => {
    const validateResult = safeParse(params.shema, Object.fromEntries(formData.entries()));
    if (!validateResult.success) {
      return {
        message: validateResult.issues[0].message,
        isError: true,
      };
    }
    const { output } = validateResult;
    try {
      return await params.onValid(output);
    } catch (e) {
      if (e instanceof Error) {
        return { message: e.message, isError: true };
      }
    }
    return null;
  };

Next, suppose the following Server Action is defined using generateFormAction.

'use server';

import { redirect } from 'next/navigation';
import { object, string } from 'valibot';
import { generateFormAction } from '@/actions';
import { prisma } from '@/libs/clients';

const Shema = object({
  title: string()
});

export const submitAction = generateFormAction({
  shema: Shema,
  onValid: async (output) => {
    await prisma.article.create({
      data: {
        ...output,
      },
    });
    // This throws Error!!
    redirect('/articles');
    // Note that not always `generateFormAction` users use `redirect` like this.
    // return { message: "The article was created!!", isError: false };
  },
});

Finally, if submitAction is used as Server Action in a form tag with useActionState , the user will not be redirected to the specified path because of thrown by redirect and .

next.js/packages/next/src/client/components/redirect.ts

Line 49 in 8bac76a

throw getRedirectError(

This is what it looks like on screen because the e.message which is NEXT_REDIRECT is displayed.

Proposal

JavaScript is a flexible language. One option is to throw objects other than Error.

throw { digest: "error code", mutableCookies: 'mutableCookies' }