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RecurrenceRule.TryParse -- throwing exceptions

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Scheduler

This is a migrated thread and some comments may be shown as answers.

Richard asked on 15 Apr 2014, 04:45 PM

We've found some cases where calling RecurrenceRule.TryParse ends up throwing an exception.
//in namespace Telerik.Web.UI
RecurrenceRule blah;
RecurrenceRule.TryParse("DTSTART:20140417T224500Z\r\nDTEND:20140417T234500Z\r\nRRULE:FREQ=YEARLY;INTERVAL=8;COUNT=1;\r\n", out blah); //exception
RecurrenceRule.TryParse("DTSTART:20140417T224500Z\r\nDTEND:20140417T234500Z\r\nRRULE:FREQ=DAILY;INTERVAL=8;COUNT=1;\r\n", out blah); //ok
RecurrenceRule.TryParse("DTSTART:20140417T224500Z\r\nDTEND:20140417T234500Z\r\nRRULE:FREQ=MONTHLY;INTERVAL=8;COUNT=1;\r\n", out blah); //exception
RecurrenceRule.TryParse("DTSTART:20140417T224500Z\r\nDTEND:20140417T234500Z\r\nRRULE:FREQ=MONTHLY;INTERVAL=1;COUNT=1;\r\n", out blah); //exception
RecurrenceRule.TryParse("DTSTART:20140417T224500Z\r\nDTEND:20140417T234500Z\r\nRRULE:FREQ=YEARLY;INTERVAL=1;COUNT=1;\r\n", out blah); //exception

Now, we can obviously wrap these calls in try/catch blocks or try to make the strings valid, but that defeats the entire purpose of the TryParse methods. They should return false if the string being passed in representing the datatype's value is invalid and/or not well formatted.

3 Answers, 1 is accepted

answered on 18 Apr 2014, 05:11 PM

Storing the values in a proper format is really a side issue at this point. My primary complaint is with the TryParse method's behavior when it gets a bad string.

From my OP:
"Now, we can obviously wrap these calls in try/catch blocks or try to make the strings valid, but that defeats the entire purpose of the TryParse methods. They should return false if the string being passed in representing the datatype's value is invalid and/or not well formatted."

There's no point in having a TryParse method at all if it's going to throw an exception when it can't parse the string into the data type. Our only recourse at this point is to wrap this "TryParse" method in a try/catch block and use exception handling to detect validation problems, which is inefficient and a bad practice.