public function getSourceValue($fieldname, $options = [])
    {
        $valueMap = [
            'data' => 'getData',
            'query' => 'getQuery'
        ];
        foreach ($this->getValueSources() as $valuesSource) {
            if ($valuesSource === 'context') {
                $val = $this->_getContext()->val($fieldname, $options);
                if ($val !== null) {
                    return $val;
                }
            }
            if (isset($valueMap[$valuesSource])) {
                $method = $valueMap[$valuesSource];
                $value = $this->_View->getRequest()->{$method}($fieldname);
                if ($value !== null) {
                    return $value;
                }
            }
        }

        return null;
    }