BoundaryML/baml · error

failed to get as url

Error message

failed to get as url: %w

What it means

Wraps any error from the FFI call to the runtime's `as_url` method, which converts media content into a URL when possible. The underlying cause is preserved via %w. Note this error is distinct from AsUrl returning nil, which simply means the runtime produced no URL for this media.

Solutions

1. Check the wrapped cause with errors.Unwrap(err)
2. Verify media.IsUrl() is true (or IsBase64) before expecting a URL conversion; use AsBase64 for base64 media
3. Re-acquire the media object from a fresh BAML response
4. Upgrade Go client and native runtime to matching versions

Example fix

// before
url, err := media.AsUrl() // may fail on base64 media
// after
isUrl, _ := media.IsUrl()
if isUrl {
    url, err := media.AsUrl()
    ...
} else {
    b64, err := media.AsBase64()
    ...
}

isUrl, err := media.IsUrl()
if err != nil || !isUrl { return nil }

url, err := media.AsUrl()
if err != nil {
    log.Printf("as_url failed: %v", err)
    if b64, berr := media.AsBase64(); berr == nil { return useBase64(b64) }
    return nil
}

When it happens

Trigger: Calling AsUrl() on media whose runtime handle is invalid/freed, or when the Rust-side `as_url` method itself errors (e.g. the stored content cannot be represented as a URL).

Common situations: Calling AsUrl on base64 data or raw bytes that have no URL form; stale handles from released responses; client/runtime version skew.

Understand the failure class

Background: "invalid response format", "malformed payload", "missing data field": when an API returns 200 but the response shape is wrong — this error's family across 23 libraries.

Related errors

• failed to get as base64
• failed to get is base64
• failed to get is url
• failed to get mime type
• decodeLiteralValue: valueLiteral is nil

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/251663c9ec39d05f. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_client_go/pkg/rawobjects_media.go:122

		return false, fmt.Errorf("failed to get is url: %w", err)
	}

	return result.(bool), nil
}

func (m *mediaHolder) IsBase64() (bool, error) {
	result, err := raw_objects.CallMethod(m, "is_base64", nil)
	if err != nil {
		return false, fmt.Errorf("failed to get is base64: %w", err)
	}

	return result.(bool), nil
}

func (m *mediaHolder) AsUrl() (*string, error) {
	result, err := raw_objects.CallMethod(m, "as_url", nil)
	if err != nil {
		return nil, fmt.Errorf("failed to get as url: %w", err)
	}

	if result == nil {
		return nil, nil
	}

	as_url, ok := result.(string)
	if !ok {
		return nil, fmt.Errorf("unexpected type for as_url: %T", result)
	}

	return &as_url, nil
}
func (m *mediaHolder) AsBase64() (*string, error) {
	result, err := raw_objects.CallMethod(m, "as_base64", nil)
	if err != nil {
		return nil, fmt.Errorf("failed to get as base64: %w", err)
	}

View on GitHub (pinned to bd85ce9dee)