1 files changed, 17 insertions, 7 deletions
diff --git a/src/guff/api-methods.cr b/src/guff/api-methods.cr
index 859e7ce..d8d1c44 100644
--- a/src/guff/api-methods.cr
+++ b/src/guff/api-methods.cr
@@ -36,6 +36,12 @@ module Guff
               required: false,
               default:  "date,desc",
             },
+
+            "cols": {
+              text:     "Column list",
+              type:     :text,
+              required: false,
+            },
           },
         },
 
@@ -296,17 +302,21 @@ module Guff
         # get value
         val = if arg_data[:required]
           params.fetch(arg_name)
-        else
+        elsif arg_data[:default]
           params.fetch(arg_name, arg_data[:default] as String)
+        else
+          nil
         end
 
-        # check value
-        if !TYPE_CHECKS[arg_data[:type]].match(val)
-          raise "invalid parameter format: %s" % [arg_name]
-        end
+        if val
+          # check value
+          if !TYPE_CHECKS[arg_data[:type]].match(val)
+            raise "invalid parameter format: %s" % [arg_name]
+          end
 
-        # add value to result
-        r[arg_name] = val
+          # add value to result
+          r[arg_name] = val
+        end
 
         # return result
         r