siyuan-note/siyuan · error

Field [assets. .box] should be of type [String]

Error message

Field [assets.%d.box] should be of type [String]

What it means

The optional box field of a rich clipboard asset must be a JSON string when present. Sending null or a non-string value (number, boolean, object, array) is rejected; the field must simply be omitted if not needed.

Solutions

1. Omit the box key entirely when there is no notebook box to specify
2. Ensure box is a string notebook ID (e.g. "20210808180117-czj9hvh") when present
3. Strip null-valued optional fields before sending the request

Example fix

// before
{index: 0, path: "/assets/a.png", box: null}
// after
{index: 0, path: "/assets/a.png"}

if ('box' in asset && (asset.box === null || typeof asset.box !== 'string')) delete asset.box;

const hasValidBox = (a) => !('box' in a) || (typeof a.box === 'string' && a.box !== null);

When it happens

Trigger: Sending {"index":0,"path":"/a.png","box":null} or box: 123 / box: {"id":"x"} in an asset of the /api/clipboard/prepareRichText payload.

Common situations: A client framework serializes undefined/absent notebook IDs as null instead of omitting the key; typed bindings pass a number where a notebook box ID string is expected; copy-pasting payload templates with placeholder null values.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Field [assets. ] should be of type [Object]
• Field [groups. ] should be of type [String]
• attr must be a string or null (got %T)
• block [ ] type is locked: expected , got
• createDocTree definition must be a list

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/30ba2d8fac023b54. Report an issue: GitHub.

Appendix: source

Thrown at kernel/apicontract/clipboard_input.go:37

			return request, err
		}
		if len(assets) == 0 {
			return request, fmt.Errorf("Field [assets] must not be empty")
		}
		request.Assets = make([]RichClipboardAsset, 0, len(assets))
		for i, raw := range assets {
			var asset map[string]json.RawMessage
			if json.Unmarshal(raw, &asset) != nil || asset == nil {
				return request, fmt.Errorf("Field [assets.%d] should be of type [Object]", i)
			}
			var index float64
			var path, box string
			if bytes.Equal(asset["index"], []byte("null")) || json.Unmarshal(asset["index"], &index) != nil || index < 0 || index != float64(int(index)) || json.Unmarshal(asset["path"], &path) != nil || strings.TrimSpace(path) == "" {
				return request, fmt.Errorf("Invalid rich clipboard asset at index [%d]", i)
			}
			if value, exists := asset["box"]; exists {
				if bytes.Equal(value, []byte("null")) || json.Unmarshal(value, &box) != nil {
					return request, fmt.Errorf("Field [assets.%d.box] should be of type [String]", i)
				}
			}
			request.Assets = append(request.Assets, RichClipboardAsset{Index: int(index), Path: strings.TrimSpace(path), Box: strings.TrimSpace(box)})
		}
		return
	}
	CleanupRichText.decodeRequest = func(reader io.Reader) (request CleanupRichTextRequest, err error) {
		fields, err := blockRequestFields(reader, "/api/clipboard/cleanupRichText")
		if err != nil {
			return request, err
		}
		request.Batch, err = legacyField[string](fields, "batch", "String", true)
		if err != nil {
			return request, err
		}
		request.Batch = strings.TrimSpace(request.Batch)
		if request.Batch == "" {
			return request, fmt.Errorf("Field [batch] must not be empty")

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