abhigyanpatwari/GitNexus · error

Missing "cypher" in request body

Error message

Missing "cypher" in request body

What it means

HTTP 400 from POST /api/query when req.body.cypher is falsy — undefined, null, or the empty string. The query endpoint requires a JSON body with a non-empty cypher string before it will resolve a repository and open the read-only LadybugDB connection. If instead you see a 500 with a TypeError message, your body was never parsed (missing Content-Type: application/json) — a different failure that this 400 is designed to preempt.

Source

Thrown at gitnexus/src/server/api.ts:651

      res.status(404).json({ error: 'File not found' });
    } else {
      // statusFromError returns err.status for BadRequestError / ForbiddenError
      // (assertString → 400 on array-form ?path=a&path=b; ForbiddenError → 403
      // on traversal). Falls back to 500 for unrecognized failures.
      res.status(statusFromError(err)).json({ error: err.message || 'Failed to read file' });
    }
  }
};

export const handleQueryRequest = async (
  req: express.Request,
  res: express.Response,
  resolveRepo: (repoName?: string) => Promise<{ storagePath: string } | undefined>,
): Promise<void> => {
  try {
    const cypher = req.body.cypher as string;
    if (!cypher) {
      res.status(400).json({ error: 'Missing "cypher" in request body' });
      return;
    }
    const queryParams = req.body.params;
    if (queryParams !== undefined && !isValidQueryParams(queryParams)) {
      res.status(400).json({
        error: '"params" must be a plain object with scalar values (string/number/boolean/null)',
      });
      return;
    }

    const entry = await resolveRepo(requestedRepo(req));
    if (!entry) {
      res.status(404).json({ error: 'Repository not found' });
      return;
    }
    const lbugPath = path.join(entry.storagePath, 'lbug');
    const result = await withLbugDb(lbugPath, () => executePrepared(cypher, queryParams ?? {}), {
      readOnly: true,

View on GitHub (pinned to aac7515d2a)

Solutions

1. Send JSON with the exact key: {"cypher": "MATCH (n) RETURN n LIMIT 5"} and header Content-Type: application/json
2. Client-side, assert a non-empty string before issuing the request
3. If you got a 500 mentioning 'cypher of undefined', your body was not parsed — set the content type
4. Pass query values via the optional params object rather than string interpolation

Example fix

// before
await fetch(`${base}/api/query`, {
  method: 'POST',
  body: JSON.stringify({ query }), // wrong key → 400
});

// after
await fetch(`${base}/api/query`, {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify({ cypher: query, params: { limit: 5 } }),
});

if (typeof cypher !== 'string' || cypher.trim() === '') throw new Error('cypher body field is required');
await fetch(`${base}/api/query`, { method: 'POST', headers: { 'content-type': 'application/json' }, body: JSON.stringify({ cypher }) });

function isQueryBody(b: unknown): b is { cypher: string; params?: Record<string, string | number | boolean | null> } {
  if (typeof b !== 'object' || b === null) return false;
  const c = (b as Record<string, unknown>).cypher;
  return typeof c === 'string' && c.length > 0;
}

When it happens

Trigger: POSTing {} or {query: 'MATCH ...'} (wrong key — the key must be exactly cypher); sending cypher: '' for a 'run nothing' call; omitting the Content-Type header so express.json skips parsing and req.body stays unset; sending form-encoded instead of JSON.

Common situations: Copy-pasting a client for the /api/grep endpoint and forgetting the query API uses a different body key; API explorers defaulting to text/plain content type; code paths that build the body conditionally and skip the cypher field when a template is empty.

Understand the failure class

Background: Missing required parameter errors: what 'X is required' and 'the required X param is missing' mean, and how to fix them — this error's family across 27 libraries.

Related errors

• "params" must be a plain object with scalar values (string/n
• "url" must be a string
• "path" must be a string
• Provide "url" (git URL) or "path" (local path)
• Missing path

AI-assisted analysis of abhigyanpatwari/GitNexus@aac7515d2a (2026-08-20). Data as JSON: /api/errors/dcf6c9819f60f1bc. Report an issue: GitHub.