chenhg5/cc-connect · info

dingtalk: marshal image message: %w

Error message

dingtalk: marshal image message: %w

What it means

This error is returned by Platform.SendImage when json.Marshal fails on the oToMessages batchSend request body (robotCode, userIds, msgKey, msgParam). It means the image-send request could not be serialized to JSON before being POSTed to DingTalk. Because the body is assembled entirely from strings and string slices in memory, a marshal failure is a defensive guard that is effectively unreachable in normal operation.

Source

Thrown at platform/dingtalk/dingtalk.go:1047

	slog.Debug("dingtalk: image uploaded", "media_id", mediaID, "size", len(img.Data))

	token, err := p.getAccessToken()
	if err != nil {
		return fmt.Errorf("dingtalk: get access token: %w", err)
	}

	msgParamBytes, _ := json.Marshal(map[string]string{"photoURL": mediaID})
	requestBody := map[string]any{
		"robotCode": p.robotCode,
		"userIds":   []string{rc.senderStaffId},
		"msgKey":    "sampleImageMsg",
		"msgParam":  string(msgParamBytes),
	}

	body, err := json.Marshal(requestBody)
	if err != nil {
		return fmt.Errorf("dingtalk: marshal image message: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost,
		"https://api.dingtalk.com/v1.0/robot/oToMessages/batchSend",
		bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("dingtalk: create image request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("x-acs-dingtalk-access-token", token)

	resp, err := p.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("dingtalk: send image request: %w", err)
	}
	defer func() { _ = resp.Body.Close() }()

	respBody, _ := io.ReadAll(resp.Body)

View on GitHub (pinned to 4000b2338a)

Solutions

1. Retry the operation — no user configuration or input causes this
2. If you modified the payload construction, revert changes that add non-JSON-serializable values
3. Report to maintainers with the wrapped error if it reproduces on stock code

if err := p.SendImage(ctx, rctx, img); err != nil {
    if strings.Contains(err.Error(), "marshal image message") {
        slog.Warn("dingtalk image marshal (unexpected)", "err", err)
    }
}

When it happens

Trigger: json.Marshal(requestBody) errors inside SendImage — only possible if a non-serializable value entered the requestBody map (channels/funcs), which the current construction (plain strings) prevents.

Common situations: Effectively none for library users; would only surface from a code modification that inserts dynamic values into the payload.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• marshal payload: %w
• marshal request: %w
• dingtalk: marshal emotion request: %w
• dingtalk: marshal file message: %w
• dingtalk: marshal proactive message: %w

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/e065db0cae873cfd. Report an issue: GitHub.