Add custom error to handle invalid param in sort

Author: krishna-chaitanya-45

lib/query_helper/invalid_sort_param_error.rb

@@ -0,0 +1,18 @@
+class QueryHelper
+  class InvalidSortParamError < StandardError
+
+    attr_reader :sort_string
+
+    def initialize(msg='Invalid sort param', sort_string='')
+      @sort_string = sort_string
+      super(msg)
+    end
+    
+    def as_json
+      {
+        'error' => message,
+        'sort_param' => sort_string
+      }
+    end
+  end
+end

lib/query_helper/sql_sort.rb

@@ -34,7 +34,9 @@ def attributes_sql_expression(sort_attribute)
           direction = sort.split(":")[1]
           modifier = sort.split(":")[2]
           begin
-            sql_expression = @column_maps.find{ |m| m.alias_name.casecmp?(sort_alias) }.sql_expression
+            sort_col = @column_maps.find{ |m| m.alias_name.casecmp?(sort_alias) }
+            raise InvalidSortParamError.new("Invalid sort param", sort_alias) if sort_col.nil?
+            sql_expression = sort_col.sql_expression
           rescue NoMethodError => e
             raise InvalidQueryError.new("Sorting not allowed on column '#{sort_alias}'")
           end