if defined param('end_date'){$user_input->{end_date} = param('end_date
+')};
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In addition to the other comments, the };, while not syntactically wrong, is probably not what you mean. Read on...

else $user_input->{end_date} = param('start_date');
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This, on the other hand, is quite wrong. With the closing }; on the if, the else no longer has meaning. Also, it should be else {..._date');}.