--- a/static/admin/lotteries/script.js
+++ b/static/admin/lotteries/script.js
@@ -229,7 +229,11 @@
             var patternWinAmounts = [];

            pattern_win_amount.each(function () {
-               patternWinAmounts.push($(this).val());
+               if ($(this).val()) {
+                   patternWinAmounts.push($(this).val());
+               } else {
+                   patternWinAmounts.push(0);
+               }
             });

             $('.pattern-win-amount-field').val(JSON.stringify(patternWinAmounts));