[Calendar] - recurrent appointment with FREQ=WEEKLY throws an exception when BYDAY parameter is missing

[angel1st]

Hi there,
It's very easy to replicate error:

1. Define

@override
String getRecurrenceRule(int index) { return 'FREQ=WEEKLY;INTERVAL=1;' }

2. It throws an error:

E/flutter (10612): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: Invalid argument(s)
E/flutter (10612): #0 List.[] (dart:core-patch/growable_array.dart:146:60)
E/flutter (10612): #1 _getRecurrenceDateTimeCollection (package:syncfusion_flutter_calendar/src/calendar/appointment_engine/recurrence_helper.dart:124:47)
E/flutter (10612): #2 _getRecurrenceAppointments (package:syncfusion_flutter_calendar/src/calendar/appointment_engine/appointment_helper.dart:1416:20)
E/flutter (10612): #3 _getVisibleAppointments (package:syncfusion_flutter_calendar/src/calendar/appointment_engine/appointment_helper.dart:1240:5)
E/flutter (10612): #4 _SfCalendarState._updateVisibleAppointments (package:syncfusion_flutter_calendar/src/calendar/sfCalendar.dart:1079:36)
E/flutter (10612): #5 _SfCalendarState._getAppointment (package:syncfusion_flutter_calendar/src/calendar/sfCalendar.dart:1071:5)
E/flutter (10612): #6 _SfCalendarState.didUpdateWidget (package:syncfusion_flutter_calendar/src/calendar/sfCalendar.dart:1446:7)
E/flutter (10612): #7 StatefulElement.update (package:flutter/src/widgets/framework.dart:4690:58)
E/flutter (10612): #8 Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (10612): #9 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:5522:32)
E/flutter (10612): #10 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5957:17)
E/flutter (10612): #11 Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (10612): #12 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (10612): #13 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (10612): #14 Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (10612): #15 StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (10612): #16 Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (10612): #17 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (10612): #18 StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (10612): #19 Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (10612): #20 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2627:33)
E/flutter (10612): #21 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:883:20)
E/flutter (10612): #22 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:284:5)
E/flutter (10612): #23 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1113:15)
E/flutter (10612): #24 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1052:9)
E/flutter (10612): #25 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:968:5)
E/flutter (10612): #26 _rootRun (dart:async/zone.dart:1184:13)
E/flutter (10612): #27 _CustomZone.run (dart:async/zone.dart:1077:19)
E/flutter (10612): #28 _CustomZone.runGuarded (dart:async/zone.dart:979:7)
E/flutter (10612): #29 _invoke (dart:ui/hooks.dart:261:10)
E/flutter (10612): #30 _drawFrame (dart:ui/hooks.dart:219:3)

[Indumathi1195R]

Hi @angel1st ,

Based on the provided information, we have checked the mentioned issue “Issue with Weekly recurrence rule”. When we create the weekly recurrence appointment, we need to specify the weekday(s) on “BYDAY” property of the recurrence rule. It is a mandatory field for creating a recurrence appointment with weekly.

Please find the UG link for the recurrence rule.

UG link: https://help.syncfusion.com/flutter/calendar/appointments#recurrence-rule

Regards,
Indumathi R

[angel1st]

Hi @Indumathi1195R and thanks for the feedback.
I have two remarks on your answer:

1. I am aware of the UG link. This is the part regarding BYDAY parameter:

It holds the “DAY” values of an appointment to render. For example, when you create the weekly appointment, select the day(s) from the day options (Monday/Tuesday/Wednesday/Thursday/Friday/Saturday/Sunday). When Monday is selected, the first two letters of the selected day “MO” is stored in the “BYDAY” property. When you select multiple days, the values are separated by commas. Example: FREQ=WEEKLY;INTERVAL=1;BYDAY=MO,WE;COUNT=10

However, I don't find UG is quite clear about BYDAY mandatory nature in case FREQ=WEEKLY.

2. Even though the field is mandatory, you should have an assert statement inside the code, which IMO is a better programming practice rather than an exception that is currently thrown from your code.

[Indumathi1195R]

Hi @angel1st ,

We will provide assert for this exception and we will improve the documentation for the same.

Regards,
Indumathi R

[loicgeek]

hello @Indumathi1195R , byDay field should not be mandatory, this rrule, RRULE:FREQ=WEEKLY;UNTIL=20210326T065900Z;INTERVAL=1 is valid and works well here : https://jakubroztocil.github.io/rrule/