HOW TO: Not allow a user to add multiple items of a meeting at the same time & date in a Calendar list for a user in SharePoint 2010
This post is a contribution from Bharat Rathod, an engineer with the SharePoint Developer Support team.
By default, SharePoint 2010 allows you to add multiple items in the calendar for the same date and time. Below screenshot shows that Meeting1 and Meeting2 occur at the same date and time for the same user.
In real world scenario, we do not let a user have multiple entries of meetings at the same date and time. For example, Outlook warns the user of the clashes of the meeting that occur at the same date and time.
Here’s a sample feature that will prevent this from occurring in your Calendar list.
The Feature.xml file
<?xml version="1.0" encoding="utf-8"?>
<Feature Scope="Site"
Title="Simple Event Handler Registration"
Id="853A4952-122D-4F97-8239-A2B02FFFDA68"
xmlns="https://schemas.microsoft.com/sharepoint/">
<ElementManifests>
<ElementManifest Location="Elements.xml"/>
</ElementManifests>
</Feature>
The Elements.xml file
<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="https://schemas.microsoft.com/sharepoint/">
<Receivers ListTemplateId="106">
<Receiver>
<Name>doublemeeting</Name>
<Type>ItemAdding</Type>
<SequenceNumber>10001</SequenceNumber>
<Assembly>doublemeeting, Version=1.0.0.0, Culture=neutral, PublicKeyToken=30c59cdee5e7a547</Assembly>
<Class>doublemeeting.PreventDoubleBooking</Class>
<Data></Data>
<Filter></Filter>
</Receiver>
<Receiver>
<Name>doublemeeting</Name>
<Type>ItemUpdating</Type>
<SequenceNumber>10001</SequenceNumber>
<Assembly>doublemeeting, Version=1.0.0.0, Culture=neutral, PublicKeyToken=30c59cdee5e7a547</Assembly>
<Class>doublemeeting.PreventDoubleBooking</Class>
<Data></Data>
<Filter></Filter>
</Receiver>
</Receivers>
</Elements>
And the complete code file
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;
namespace doublemeeting
{
public class PreventDoubleBooking : SPItemEventReceiver
{
/// <summary>
/// This event is triggered when the user adds a new item
/// </summary>
/// <param name="properties"></param>
public override void ItemAdding(SPItemEventProperties properties)
{
//Our query string variable
string strQuery = null;
try
{
//Get the Sharepoint site instance
using (SPWeb oWebsite = new SPSite(properties.SiteId).OpenWeb(properties.RelativeWebUrl))
{
//Get the collection of properties for the Booking item
SPListItemCollection collItems = oWebsite.Lists[properties.ListTitle].Items;
//Get the Calendar List that we will be querying against
SPList calendar = oWebsite.Lists[properties.ListId];
//Get the internal name of the fields we are querying.
//These are required for the CAML query
string start_internal = collItems.List.Fields["Start Time"].InternalName;
string end_internal = collItems.List.Fields["End Time"].InternalName;
string Category_Internal = collItems.List.Fields["Category"].InternalName;
//Get the query string parameters
string start_str = properties.AfterProperties[start_internal].ToString();
string end_str = properties.AfterProperties[end_internal].ToString();
string Category_str = properties.AfterProperties[Category_Internal].ToString();
//Construct a CAML query
SPQuery query = new SPQuery();
//Create the CAML query string that checks to see if the booking we are attemping
//to add will overlap any existing bookings
strQuery = string.Format(@"
<Where>
<And>
<Or>
<Or>
<And>
<Leq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Leq>
<Gt>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Gt>
</And>
<And>
<Lt>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Lt>
<Geq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Geq>
</And>
</Or>
<Or>
<And>
<Leq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Leq>
<Geq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Geq>
</And>
<And>
<Geq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Geq>
<Leq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Leq>
</And>
</Or>
</Or>
<Eq>
<FieldRef Name='Category' />
<Value Type='Choice'>{2}</Value>
</Eq>
</And>
</Where>
<OrderBy>
<FieldRef Name='EventDate' />
</OrderBy>
", start_str, end_str, Category_str);
//Set the query string for the SPQuery object
query.Query = strQuery;
//Execute the query against the Calendar List
SPListItemCollection existing_events = calendar.GetItems(query);
//Check to see if the query returned any overlapping bookings
if (existing_events.Count > 0)
{
//Cancels the ItemAdd action and redirects to error page
properties.Cancel = true;
//Edit the error message that will display on the error page
properties.ErrorMessage += "This booking cannot be made because of one or more bookings in conflict. <BR><BR>";
//Here you can loop through the results of the query
//foreach (SPListItem oListItem in existing_events)
//{
// ....
//}
properties.ErrorMessage += "Please go back and schedule a new time.";
}
}
}
catch (Exception ex)
{
//Cancels the ItemAdd action and redirects to error page
properties.Cancel = true;
//Edit the error message that will display on the error page
properties.ErrorMessage = "Error looking for booking conflicts: " + ex.Message;
}
}
/// <summary>
/// This event is triggered when the user edits an calendar item
/// </summary>
/// <param name="properties"></param>
public override void ItemUpdating(SPItemEventProperties properties)
{
string strQuery = null;
try
{
//Get the Sharepoint site instance
using (SPWeb oWebsite = new SPSite(properties.SiteId).OpenWeb(properties.RelativeWebUrl))
{
//Get the collection of properties for the Booking item
SPListItemCollection collItems = oWebsite.Lists[properties.ListTitle].Items;
//Get the Calendar List that we will be querying against
SPList calendar = oWebsite.Lists[properties.ListId];
//Get the internal name of the fields we are querying.
//These are required for the CAML query
string start_internal = collItems.List.Fields["Start Time"].InternalName;
string end_internal = collItems.List.Fields["End Time"].InternalName;
string Category_Internal = collItems.List.Fields["Category"].InternalName;
string guid_internal = collItems.List.Fields["GUID"].InternalName;
//Get the query string parameters
string start_str = properties.AfterProperties[start_internal].ToString();
string end_str = properties.AfterProperties[end_internal].ToString();
string Category_str = properties.AfterProperties[Category_Internal].ToString();
string guid_str = properties.AfterProperties[guid_internal].ToString();
//Construct a CAML query
SPQuery query = new SPQuery();
//Create the CAML query string that checks to see if the booking we are attemping
//to change will overlap any existing bookings, OTHER THAN ITSELF
strQuery = string.Format(@"
<Where>
<And>
<And>
<Or>
<Or>
<And>
<Leq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Leq>
<Gt>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Gt>
</And>
<And>
<Lt>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Lt>
<Geq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Geq>
</And>
</Or>
<Or>
<And>
<Leq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Leq>
<Geq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Geq>
</And>
<And>
<Geq>
<FieldRef Name='EventDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{0}</Value>
</Geq>
<Leq>
<FieldRef Name='EndDate' />
<Value Type='DateTime' IncludeTimeValue='TRUE'>{1}</Value>
</Leq>
</And>
</Or>
</Or>
<Eq>
<FieldRef Name='Category' />
<Value Type='Choice'>{2}</Value>
</Eq>
</And>
<Neq>
<FieldRef Name='GUID' />
<Value Type='GUID'>{3}</Value>
</Neq>
</And>
</Where>
<OrderBy>
<FieldRef Name='EventDate' />
</OrderBy>
", start_str, end_str, Category_str, guid_str);
//Set the query string for the SPQuery object
query.Query = strQuery;
//Execute the query against the Calendar List
SPListItemCollection existing_events = calendar.GetItems(query);
//Check to see if the query returned any overlapping bookings
if (existing_events.Count > 0)
{
//Cancels the ItemAdd action and redirects to error page
properties.Cancel = true;
//Edit the error message that will display on the error page
properties.ErrorMessage += "This booking cannot be made because of one or more bookings in conflict. <BR><BR>";
//Here you can loop through the results of the query
//foreach (SPListItem oListItem in existing_events)
//{
// ....
//}
properties.ErrorMessage += "Please go back and schedule a new time.";
}
}
}
catch (Exception ex)
{
//Cancels the ItemAdd action and redirects to error page
properties.Cancel = true;
//Edit the error message that will display on the error page
properties.ErrorMessage = "Error looking for booking conflicts: " + ex.Message;
}
}
}
}
Below are the source code and the feature file samples for your reference.
Feature: DoubleMeeting Feature
Sample source code: DoubleMeetingSource
Hope this post was helpful!
Comments
Anonymous
January 01, 2003
@TrevoR2300: You should be able to implement the same in a SP 2010 Foundation. For more details of Event Receivers in SP 2010 Foundation, you can refer this MSDN link:-msdn.microsoft.com/.../gg749858(v=office.14).aspxAnonymous
January 01, 2003
Hi Can you tell me please how can intall it in a sharepoint foundation? ThanksAnonymous
January 01, 2003
@Anahr: so, this is a custom Event Receiver solution which we are deploying. We would also need to modify the Feature.xml associated with the Feature and the Element.xml & code-behind files for the Event Receiver as mentioned above. For more details onto how to create a sample Event Receiver solution, you can refer this MSDN link:- msdn.microsoft.com/.../gg252010(v=office.14).aspxAnonymous
January 01, 2003
See if this helps - www.ehow.com/how_5905423_publish-existing-outlook-calendar-sharepoint.html.Anonymous
August 03, 2012
Many thanks for this post. This will allow me to use this in my office environment. I am just checking with you; is there any way we can link Outlook 2010 - room booking calendar with sharepoint calendar. Just a check. Cheers SathyaAnonymous
August 27, 2013
Can you please provide some guidance on how this is deployed?Anonymous
June 09, 2014
Nice solution, but it will not work for new recurring events. You need to extract the RecurrenceData and parse it....Anonymous
March 08, 2015
This code does not validate duplicate recurring event occurrences. Appreciate if you can help on this....