How to prevent overlapping events using Linq + Entity Framework

Question

I'm wondering if anyone can help me? I'm trying to prevent events from overlapping in a room booking system. Each event has a start date/time and an end date/time. What I want to happen is if a user tries to book an event between times that already exist for an event it should error.

So for example the following should error as they overlap:-

Event 1:
- Start Date/Time: 10/08/2012 09:00
- End Date/Time: 10/08/2012 11:00

Event 2:
- Start Date/Time: 10/08/2012 10:00
- End Date/Time: 10/08/2012 12:00

I'm using MVC and Entity Framework, so a Linq solution would be preferable.

Any help would be much appreciated :)

See http://stackoverflow.com/questions/4446112/search-for-interval-overlap-in-list-of-intervals for solutions. — Martin Liversage, Aug 10 '12 at 09:21

dommer · Accepted Answer · 2012-08-10T11:10:38.910

3

Do you mean something like this:

new List<Event>()
{
    new Event() { StartsAt = DateTime.Now.AddHours(-1), EndsAt = DateTime.Now.AddHours(1) } 
};

Event newEvent = new Event() { StartsAt = DateTime.Now.AddHours(-3), EndsAt = DateTime.Now.AddHours(-2) };
bool newEventBookable = !existingsEvents.Any(x => x.StartsAt <= newEvent.EndsAt && x.EndsAt >= newEvent.StartsAt);

You can then just throw an error if newEventBookable is false.

I think this logic is OK for prior, subsequent, overlapping and contained events - but I'll soon find out if it it's not!

edited Aug 10 '12 at 11:10

answered Aug 10 '12 at 11:01

dommer

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Thank you thats exactly what i was after :) – Vince Ashby-Smith Aug 10 '12 at 14:25
Agrees with http://stackoverflow.com/a/2368885/610832, though I find yours easier to follow. – zacharydl Oct 31 '14 at 03:43
I wanted to allow back-to-back appointments, so I changed `<=` and `>=` to only `` – zacharydl Oct 31 '14 at 04:11

How to prevent overlapping events using Linq + Entity Framework

1 Answers1