SigNoz/signoz · error

key is empty

Error message

key is empty

What it means

AttributeKey.Validate() requires the Key string itself to be non-empty; everything else (dataType, type) is meaningless without an attribute name to bind to.

Source

Thrown at pkg/query-service/model/v3/v3.go:416

func (a AttributeKey) Validate() error {
	switch a.DataType {
	case AttributeKeyDataTypeBool, AttributeKeyDataTypeInt64, AttributeKeyDataTypeFloat64, AttributeKeyDataTypeString, AttributeKeyDataTypeArrayFloat64, AttributeKeyDataTypeArrayString, AttributeKeyDataTypeArrayInt64, AttributeKeyDataTypeArrayBool, AttributeKeyDataTypeUnspecified:
		break
	default:
		return fmt.Errorf("invalid attribute dataType: %s", a.DataType)
	}

	if a.IsColumn {
		switch a.Type {
		case AttributeKeyTypeResource, AttributeKeyTypeTag, AttributeKeyTypeUnspecified, AttributeKeyTypeInstrumentationScope:
			break
		default:
			return fmt.Errorf("invalid attribute type: %s", a.Type)
		}
	}

	if a.Key == "" {
		return fmt.Errorf("key is empty")
	}

	return nil
}

type FilterAttributeValueResponse struct {
	StringAttributeValues []string                      `json:"stringAttributeValues"`
	NumberAttributeValues []interface{}                 `json:"numberAttributeValues"`
	BoolAttributeValues   []bool                        `json:"boolAttributeValues"`
	RelatedValues         *FilterAttributeValueResponse `json:"relatedValues,omitempty"`
}

type QueryRangeParamsV3 struct {
	Start          int64                  `json:"start"`
	End            int64                  `json:"end"`
	Step           int64                  `json:"step"` // step is in seconds; used for prometheus queries
	CompositeQuery *CompositeQuery        `json:"compositeQuery"`
	Variables      map[string]interface{} `json:"variables,omitempty"`

View on GitHub (pinned to 5069bf80b0)

Solutions

1. Ensure every filter/group-by key object has a non-empty key string (e.g. "http.method")
2. Validate filter rows client-side for completeness before building the request
3. Check for JSON field-name mismatches if you're constructing keys manually

Example fix

// before
{"key":{"key":"","dataType":"string"},"value":"GET","operator":"="}

// after
{"key":{"key":"http.method","dataType":"string"},"value":"GET","operator":"="}

if key.Key == "" { return errors.New("attribute key name is empty") }

func hasKeyName(k v3.AttributeKey) bool { return strings.TrimSpace(k.Key) != "" }

When it happens

Trigger: A FilterItem or aggregate attribute in a /api/v3 query payload where the key object is present but its key field is "" — e.g. an incomplete filter row or a JSON path bug writing the attribute name to the wrong property.

Common situations: UI serializing a filter row before the user picks an attribute, struct field shadowing or typos (name vs key), default-constructed key objects.

Understand the failure class

Background: "Missing required field" and "field is required" errors: why libraries reject payloads that omit mandatory fields — this error's family across 20 libraries.

Related errors

• invalid attribute type: %s
• invalid operator: %s
• invalid reduce to operator: %s
• invalid query type: %s
• filterAttributeKey is required

AI-assisted analysis of SigNoz/signoz@5069bf80b0 (2026-08-28). Data as JSON: /api/errors/a839e0ede49311d2. Report an issue: GitHub.