jackwener/OpenCLI · error · ArgumentError

Invalid subreddit name.

Error message

Invalid subreddit name.

What it means

`parseSubredditName` throws this ArgumentError when the name, after stripping an optional `r/` or `/r/` prefix, fails SUBREDDIT_NAME_RE (/^[A-Za-z][A-Za-z0-9_]{2,20}$/). Valid subreddit names are 3–21 characters, must start with a letter, and contain only letters, digits, and underscores. The library validates locally so bad names never reach Reddit's API.

Source

Thrown at clis/reddit/subreddit-info.js:19

import { ArgumentError, CommandExecutionError, EmptyResultError } from '@jackwener/opencli/errors';
import { cli, Strategy } from '@jackwener/opencli/registry';

// Reddit subreddit names: 3–21 chars, letters/digits/underscore, must start
// with a letter. Accept an optional `r/` prefix and normalise it off.
const SUBREDDIT_NAME_RE = /^[A-Za-z][A-Za-z0-9_]{2,20}$/;

export function parseSubredditName(raw) {
    let name = String(raw || '').trim();
    if (!name) {
        throw new ArgumentError(
            'Subreddit name is required.',
            'Pass a subreddit name like `python` (or `r/python`).',
        );
    }
    if (name.startsWith('/r/')) name = name.slice(3);
    else if (name.startsWith('r/')) name = name.slice(2);
    if (!SUBREDDIT_NAME_RE.test(name)) {
        throw new ArgumentError(
            'Invalid subreddit name.',
            'Subreddit names are 3–21 characters, start with a letter, and contain only letters, digits, and underscores.',
        );
    }
    return name;
}

cli({
    site: 'reddit',
    name: 'subreddit-info',
    access: 'read',
    description: 'Show metadata for a Reddit subreddit (subscribers, description, created date, NSFW)',
    domain: 'reddit.com',
    strategy: Strategy.COOKIE,
    browser: true,
    args: [
        { name: 'name', type: 'string', required: true, positional: true, help: 'Subreddit name (no `r/` prefix needed)' },
    ],

View on GitHub (pinned to 49907e53dc)

Solutions

1. Pass only the bare subreddit name: `sub python` or `sub r/python`, not a URL
2. Strip 'https://www.reddit.com/r/' prefixes from pasted URLs, keeping just the name segment
3. Verify the name is 3–21 chars, starts with a letter, and uses only [A-Za-z0-9_]
4. Validate with the same regex in your own code before calling, to give a friendlier message

Example fix

// before
await runCli(['reddit', 'sub', 'https://www.reddit.com/r/AskProgramming/']); // invalid
// after
const name = 'https://www.reddit.com/r/AskProgramming/'.match(/reddit\.com\/r\/([A-Za-z0-9_]+)/)?.[1];
await runCli(['reddit', 'sub', name]); // 'AskProgramming'

// Mirror the library's own regex before calling:
const SUBREDDIT_NAME_RE = /^[A-Za-z][A-Za-z0-9_]{2,20}$/;
function toSubredditName(raw) {
  let name = String(raw ?? '').trim().replace(/^\/r\//, '').replace(/^r\/, '');
  name = name.replace(/^https?:\/\/[^/]*reddit\.com\/r\//, '').split('/')[0];
  if (!SUBREDDIT_NAME_RE.test(name)) throw new Error(`Invalid subreddit name: ${name}`);
  return name;
}

function isValidSubredditName(v) {
  return typeof v === 'string' && /^[A-Za-z][A-Za-z0-9_]{2,20}$/.test(v.replace(/^(\/r\/|r\/)/, ''));
}

try {
  await runCli(['reddit', 'sub', raw]);
} catch (e) {
  if (e instanceof ArgumentError && /Invalid subreddit name/.test(e.message)) {
    console.error('Names are 3-21 chars, start with a letter, [A-Za-z0-9_] only. Pass `python` or `r/python`.');
  } else throw e;
}

When it happens

Trigger: Passing names like 'ab' (too short), '4chan' (starts with digit — though real subs cannot start with digits anyway), names with hyphens/dots/spaces, URLs like 'reddit.com/r/python' that were not reduced to just the name, or names longer than 21 characters.

Common situations: Pasting a full subreddit URL instead of the name; passing 'r/' with nothing after it; including query strings or trailing slashes; typos or non-Latin characters in the name.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• coingecko currency must look like a currency slug (got "${ar
• designer must be a Dribbble username or profile slug
• lichess username "${value}" is not a valid handle. Allowed:
• packagist package "${value}" is not a valid Composer name
• Subreddit name is required.

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/5b346181cd016cb4. Report an issue: GitHub.