def field_value_factor(settings, options = {})
      scoring = options.merge(field_value_factor: settings)
      chain { criteria.update_scores scoring }
    end
def field_value_factor(settings, options = {})
      scoring = options.merge(field_value_factor: settings)
      chain { criteria.update_scores scoring }
    end
Add a field value scoring to the search. All scores are
 added to the search request and combinded according to
 `boost_mode` and `score_mode`

 This function is only available in Elasticsearch 1.2 and
 greater

 @example
   UsersIndex.field_value_factor(
                {
                  field: :boost,
                  factor: 1.2,
                  modifier: :sqrt
                }, filter: { foo: :bar})
       # => {body:
              query: {
                function_score: {
                  query: { ...},
                  functions: [{
                    field_value_factor: {
                      field: :boost,
                      factor: 1.2,
                      modifier: :sqrt
                    },
                    filter: { foo: :bar }
                  }]
                } } }