SharePoint DateTime format is incorrect

Problem: The SharePoint DateTimeControl displays the date in US format i.e. 1033 or mm/dd/yyyy despite me changing the site collections regional settings.
Site Settings > Regional Settings > Locale > Select [English (United Kingdom)]

Inital Hypothesis: In MOSS changing the Locale did not change the format of the DateTimeControl. 
Resolution: This is still the case, you need to explicitly set the local on eash DateTimeControl.  You can set it to be the same as the site's local.
E.g. myDateTimeControl.LocaleId = SPContext.Current.Web.Locale.LCID 
Or set the "LocaleId"attribute of the SharePoint DateTime control
E.g. SharePoint:DateTimeControl runat="server" LocaleId="2057"

=========================
Tip: Changing the Regional settings will affect the curreny columns.

List of Locale's: http://msdn.microsoft.com/en-us/goglobal/bb964664.aspx

====================

Using CAML and SPQuery to query using dates

Problem: Using SPQuery I can't filter using a datatime parameter.
Hypothesis: I can see my custom web part code is formatting the DateTime selection (SharePoint:DateTimeControl) differently in my custom code CAML than the CAML generated by U2U.
Resolution:
Use the Microsoft.SharePoint.Utilities.SPUtility.CreateISO8601DateTimeFromSystemDateTime() method to get your DateTime control value into the correct format.
SPUtility.CreateISO8601DateTimeFromSystemDateTime(DateTime.UtcNow)

More Info:
http://blogs.msdn.com/b/saurabhkv/archive/2008/05/05/spquery-with-boolean-and-datetime.aspx
http://snahta.blogspot.com/2009/07/spquery-few-important-things.html
http://www.aidangarnish.net/post/Using-SPQuery-and-CAML-to-filter-and-order.aspx

SPGridView explained

Overview:  The SPGridView is similar to the asp GridView.  The SPGridView is derived from the aspGridView and has additional functionality.  The SPGridView does not support the property AutoGenerateColumns, you must specify each SPBoundField.

Example: SPBoundFields such as "BoundField" are used to display datasource columns.

 

Example: To format a bound column use the property "DataFormatString", e.g. colDate.DateFormatString = "{0:d}";, this will display the short date only from a DateTime type.  If you need more advanced formating such as for a multi choice field, create a new class that derives from BoundField and use it in the SPGridView.

Tip: Don't use DataKeyName on the SPDataGrid, it causes the error "Unable to cast object of type 'System.Int32' to type 'System.String'.".

Read More:

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.webcontrols.spgridview.aspx

http://msdn.microsoft.com/en-us/library/bb466219(office.12).aspx

Multiple Choice Field

Multiple Choice Field

Field Class: SPFieldMultiChoice
Field Value Class: SPFieldMultiChoiceValue
Populating Information:

SPFieldMultiChoiceValue itemVal = new SPFieldMultiChoiceValue();
itemVal.Add("Choice a");
itemVal.Add("Choice b");
itemVal.Add("Choice c");
item["FieldName"] = itemVal;
item.Update();

Delimiter, you may want to delimite the multichoice field, this is ";#", or SPFieldMultiChoiceValue.Delimiter.  The delimiter can be useful for building SPFieldMultiChoiceValue objects or display purposes.

More Info:
http://sharepointcodeblock.blogspot.com/2008/07/properly-populating-and-retrieving.html
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spfieldmultichoicevalue.aspx

SPDataGrid error 'Unable to cast object of type int32 - SPDataGrid.NewPageIndex property and DataKeyNames

Problem: SPDataGrid can't use DataKeyNames, it results in the error "Unable to cast object of type 'System.Int32' to type 'System.String'." when paging or filtering.

Hypothesis: This looks like a bug in the implementation of the SPGridView.  The property DataKeyNames causes the error.

Resolution: To pass values using buttons or check boxes inside you SPGridView rather use the row index to get the row and read the Id or data you need from the row.

More info:
http://www.sharepointoverflow.com/questions/4481/using-code-compiled-for-moss-2007-in-2010

Programtically send email in SharePoint 2010

using Microsoft.SharePoint.Utilities;

if (!SPUtility.SendEmail(SPContext.Current.Web, false, false, "paul@demo.com", "subject", "Please read!"))
  {
    //TODO! log mail issue
  }

Creating a lookup list & project field lookup using a declaritive content type

Problem: Create a list that has a lookup column and a projected field from the lookup column.

Example:

• Some code I used to create a lookup column (Agency ID) in a list and a field to be brought in from the lookup list also (AgencyName)
• This should be plugged into the new list's content type (AgencyContact).
• The column being brought across also (Agency Name) needs to reference the GUID of the lookup column it relies on (Agency ID) using FieldRef.

Thanks to Paul W