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In Sharepoint 2010 calendars, how can I stop users to create more than one item in the same day and hour? We'd like to prevent meeting time conflicts.

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up vote 2 down vote accepted

I think you can do this by changing the config of the calendar to a group calendar, but they would have to click the "Check Double Booking" button on the UI...i.e. enabling this feature wouldn't prevent them from saving the event/meeting, it would just warn them that there is a double-booking. Here's a walk-thru on configuring a SharePoint calendar as a group calendar:

  1. In a SharePoint calendar, in the ribbon, click the Calendar tab, and then click List Settings.
  2. Under General Settings, click Title, description and navigation.
  3. In the Group Calendar Options section, set Use this calendar to share member’s schedules to Yes. This enables you to create events in the calendar with attendees.
  4. If you want to use this calendar to scheduled resources, such as conference rooms, as well as people, set Use this calendar for resource reservation to Yes. This enables you to create events in the calendar that include resources, such as conference rooms. NOTE: if the Use this calendar for resource reservation option is not available, the Group Work Lists feature needs to be enabled for the site.

  5. Click Save.

I don't think this is a perfect solution, but it is a no-code solution. I'm not sure I would recommend an event receiver because short of throwing an unhandled exception (...ugly) there's not much you can do to provide feedback to the user on what went wrong.

You might want to consider a custom SPField that simply (...and automatically) checks for the existence of a dupe event/meeting during the same time slot in it's validation event and throws an exception if there is a dupe...the exception would surface as an error message in the event item UI, giving them the opportunity to correct it.

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There are several options to achieve that:

  1. We can enable the Enforce Unique Value option to the Field
  2. By using ItemAdding event handler, we can check the new item with old items and prevent the user from adding items.
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Welcome to SharePoint Stack Exchange! I edited your question to improve its formatting. Take a look at our editing help page for details on how to make your posts look great! – Alex Angas Aug 22 '11 at 3:57

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