Method evalField

util/jsonpath/jsonpath.go:339–377

evalField evaluates field of struct or key of map.

(input []reflect.Value, node *FieldNode)

// evalField evaluates field of struct or key of map.
func (j *JSONPath) evalField(input []reflect.Value, node *FieldNode) ([]reflect.Value, error) {
	results := []reflect.Value{}
	// If there's no input, there's no output
	if len(input) == 0 {
		return results, nil
	}
	for _, value := range input {
		var result reflect.Value
		value, isNil := template.Indirect(value)
		if isNil {
			continue
		}

		if value.Kind() == reflect.Struct {
			var err error
			if result, err = j.findFieldInValue(&value, node); err != nil {
				return nil, err
			}
		} else if value.Kind() == reflect.Map {
			mapKeyType := value.Type().Key()
			nodeValue := reflect.ValueOf(node.Value)
			// node value type must be convertible to map key type
			if !nodeValue.Type().ConvertibleTo(mapKeyType) {
				return results, fmt.Errorf("%s is not convertible to %s", nodeValue, mapKeyType)
			}
			result = value.MapIndex(nodeValue.Convert(mapKeyType))
		}
		if result.IsValid() {
			results = append(results, result)
		}
	}
	if len(results) == 0 {
		if j.allowMissingKeys {
			return results, nil
		}
		return results, fmt.Errorf("%s is not found", node.Value)
	}
	return results, nil
}

// evalWildcard extracts all contents of the given value
func (j *JSONPath) evalWildcard(input []reflect.Value, node *WildcardNode) ([]reflect.Value, error) {