chenhg5/cc-connect · error

%s: resource download requires non-empty messageID and fileK

Error message

%s: resource download requires non-empty messageID and fileKey

What it means

downloadResourceChunked refuses to run when messageID or fileKey is empty/whitespace. These values come from the inbound message envelope and are required to build the Feishu resource-download URL; the guard exists because the function itself documents that callers must pre-validate them.

Source

Thrown at platform/feishu/resource_download.go:77

// Behaviour:
//   - Always issues a single Range bytes=0-0 GET first. If the server honours
//     Range (206) we then loop the remaining chunks; if it doesn't (200) we
//     already have the full body — done.
//   - On any transient network error mid-loop: retries with exponential
//     backoff up to maxTransientRetries before giving up.
//
// One GET is the minimum regardless of file size: small files return 200 and
// we are done; large files return 206 with the first chunk, then we loop.
// This avoids the wasted HEAD round-trip and keeps the "small file" path
// observable as exactly one outbound request, matching pre-#1741 behaviour
// for files under Feishu's streaming cap.
//
// messageID and fileKey come from the inbound message envelope; resType is
// the Feishu resource-type segment ("file", "image", ...). The caller MUST
// guarantee these have already been validated (no empty strings).
func (p *Platform) downloadResourceChunked(ctx context.Context, messageID, fileKey, resType string) ([]byte, error) {
	if strings.TrimSpace(messageID) == "" || strings.TrimSpace(fileKey) == "" {
		return nil, fmt.Errorf("%s: resource download requires non-empty messageID and fileKey", p.tag())
	}
	if p.resourceDownloadHTTP == nil {
		// Defensive: callers running outside the normal constructor (notably
		// unit tests that synthesise a Platform value) still get a sane
		// client. We log instead of panicking so one stale test fixture
		// doesn't crash the whole process.
		slog.Warn(p.tag() + ": resourceDownloadHTTP is nil; using default client")
		p.resourceDownloadHTTP = &http.Client{Timeout: 60 * time.Second}
	}
	if p.resourceChunkSize <= 0 {
		p.resourceChunkSize = defaultResourceChunkSize()
	}
	if p.resourceMaxBytes <= 0 {
		p.resourceMaxBytes = defaultResourceMaxBytes
	}

	token, err := p.fetchResourceTokenOrDefault(ctx)
	if err != nil {

View on GitHub (pinned to 4000b2338a)

Solutions

1. Validate messageID and fileKey are non-empty at the call site before invoking downloadResource/downloadImage
2. Inspect the inbound message envelope — the field was likely absent in the original message
3. Trim whitespace and reject earlier in the message-parsing layer with a clearer error
4. If the message legitimately lacks a fileKey, handle that message type separately instead of attempting a resource download

Example fix

// before
p.downloadResource(ctx, msgID, fileKey, "image")
// after
if strings.TrimSpace(msgID) == "" || strings.TrimSpace(fileKey) == "" {
    return nil, fmt.Errorf("feishu: cannot download resource: empty messageID or fileKey")
}
p.downloadResource(ctx, msgID, fileKey, "image")

if strings.TrimSpace(messageID) == "" || strings.TrimSpace(fileKey) == "" {
    return fmt.Errorf("feishu: resource download needs non-empty messageID and fileKey")
}

data, err := p.DownloadImage(ctx, msgID, fileKey)
if err != nil {
    if strings.Contains(err.Error(), "non-empty messageID") {
        // skip download; message lacked a usable key
    }
}

When it happens

Trigger: downloadImage/downloadResource called with an empty or whitespace-only messageID or fileKey — e.g. an inbound message missing an image key, or a caller passing zero-value strings.

Common situations: Upstream message parsing produced empty file_key (unsupported message type); caller forgot to trim/validate envelope fields; tests synthesizing Platform values with blank identifiers.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• app_id/app_secret are required
• invalid remote image URL
• invalid --platform-type %q, want feishu or lark
• unknown validation error
• decode response: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/14f8980b898fed99. Report an issue: GitHub.