iCustomMapping LinkFieldValue errors in Sandbox solutions

Problem:  I was trying to use the iCustomMapping interface to add additional columns of type LinkFieldValue to a sandox solution I am getting the error:
{"Type 'Microsoft.SharePoint.Publishing.Fields.LinkFieldValue' in Assembly 'Microsoft.SharePoint.Publishing, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' is not marked as serializable."}

Initial Hypothesis: I could not see why I as getting the error but a Google search found me a post that gave me the answer.

Resolution:  Change the code from
SPListItem item = (SPListItem)listItem;
this.ContentLinkField = item["LT1"];
To:
SPListItem item = (SPListItem)listItem;
string value = item.GetFormattedValue("LT1");
this.ContentLinkField = new LinkFieldValue(value);

More info:
http://www.alexbruett.net/?p=255 

WebControls not supported in sandbox solutions

Problem:  I wanted to use a SPGridView in a sandbox solution, so I added the code an intellesense doesn't pick it up.  Looked up the SPGridView class documentation on MSDN and it's not supported.  Not really sure why but hardly anything in the Microsoft.SharePoint.WebControls assembly works with sandbox solutions.

Initial Hypothesis:
Microsoft.SharePoint.WebPartPages.ListViewWebPart is another example of a control that can't be added progratically, however it can be added using SharePoint Designer.  I'm baffled!

File Upload Size Limits

Problem: Need to store files in excess of 2GB in SharePoint.
Initial Hypothesis:

• 50MB is the default upload limit set by SharePoint OOTB.  You can change this on the farm as described here by Dave Coleman up to 2GB or 2047MB. 
• A common misconception is that by using RBS and not you content database to store the blob you can overcome this 2GB limit.  We it's partly true...  The maximum file size for a file in SQL Server is 2GB however, the next restraint is SharePoint 2010 Server Object Model and this has a hard limit of 2GB for an upload so moving to RBS won't overcome the problem.
• I believe SharePoint limit's the upload to 2GB due to IIS's worker process w3wp.exe, to upload a file you need to use all the IIS available memory to upload the full stream.  Each w3wp.exe worker process runs well with 2-4GB of memory, this is not a boundary just a good idea (on x64), therefore this makes sense to me that the SP2010 team have limited any file upload to 2GB.
• Also be aware that increasing you upload file size to 2 GB has performance ramifications so it a user uploads a file and there is no memory available no new requests can be handled until the memory is available again.

Resolution:  Store large files outside SharePoint and surface them in SharePoint.  I believe there is another solution available using a Telerik Silverlight upload control but I haven't tried it.
More Info:
http://blah.winsmarts.com/2010-3-Large_File_Upload_in_SharePoint_2010.aspx

Update 24/07/2013: SharePoint 2013 has the same hard limit of 2 GB for the maximum upload size.  Technet states 50 MB is the default limit for SP2013, the default from an OOTB install is 250MB which is the same value you get with SharePoint Online/Office 365.

Corrupt site column cannot be deleted

Problem: I have deployed a site column (field) and Content Type declaratively, the site column is not valid and I get the following error when looking at my site columns using SharePoint 2010's UI: "Field type xxx is not installed properly. Go to the list settings page to delete this field."

Initial Hypothesis:  The cause of the issue is simply that I create a site column of type "Bool", Type bool does not exist, boolean is the correct type, as show below:

Resolution: Delete the Site Column, can't do this I tried SharePoint's UI (as shown in the problem image), SharePoint Designer, Solution Explorer with CKSDev extensions.  All tools error as the Site Column object cannot in instantiated.

So now it was time to try Powershell which will fail as it can't instantiate the Site column object either. 
PS> $web = Get-SPweb http://demo1/sites/sponline
PS> $fields = $web.Fields
PS> foreach($field in $fields) {  write-host $field.Id }

This proves the site column exists but it is corrupted.  I tried deleting it using PS.
Obviously the site column won't be removed. 

Summary:  At this point I am in a knot.  The site column is causing errors and it can't be removed, so the option is to delete the site collection or to do the bad stuff and fix the error directly in the database.

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

Problem:  A corrupt site column needs to be deleted using T-SQL.

Initial Hypothesis: Find the corrupt/offending field, as you can't use SharePoint's API to remove the field, it will need to be done directly in the content database using T-SQL.

Resolution:

1. Find the site column causing the issue using Powershell.
2. I opened the field.text file and found:   I did a search for "bool" in the text document, there are a lot of results but all the other found "boolean".  So simply search for the type that is shown in your error message.
3. Find the content database that is storing the offending Site Column using Central Admin.

4.> Open "Microsoft SQL Server Management Studio" and perform a query to find the offending record

T-SQL:  SELECT * FROM [Demo_PortalDB].[dbo].[ContentTypes] WHERE Definition LIKE ('%332B55548E6C%')
5.> Delete the offending record

T-SQL: DELETE FROM [Demo_PortalDB].[dbo].[ContentTypes] WHERE Definition LIKE ('%332B55548E6C%')

Summary:  Editing SharePoint database directly is not supported by Microsoft and should not be done under any circumstances.  I can't find another way to fix this issue - so if anyone has a suggestions I'd love to know it.

Error Message Examples:
Field type Bool is not installed properly. Go to the list settings page to delete this field.
Field type Financials Gross Value Certified is not installed properly. Go to the list settings page to delete this field.
Field type UKTelephone is not installed properly. Go to the list settings page to delete this field.

SharePoint Retreat South West London

Overview:  Ashraf Islam & I are presenting a SharePoint Retreat on 14 May in Cobham (South West London).  We are looking at LINQ to SharePoint & InfoPath on the day.  This event broadly follows Andrew Woodward's SharePoint Retreat format: so it's free, everyone attending will get real world coding practice and we to retrospectives after each session.  http://www.21apps.com/sharepoint/spretreat-swlondon2011/
To book for the event: http://spretreatswlondon.eventbrite.com/

LINQ to SharePoint Session Downloads:

VS project - create lists & set up referential integrity.

VS project - deploy a visual user control web part via a sandbox solution. 

Slide Deck

Update 14 May 2011 - Thanks to everyone - i gained a lot from the day, good to meet a and discuss things with some passionate devs & architects - paul

Update 15 May 2011 - SPRetreat roundup - http://blog.sharepointsite.co.uk/2011/05/sharepoint-retreat-roundup.html

Update 28 May 2011 - Video I recorded on using LINQ to SharePoint

SP2010 Data Access options for developers

Overview:  This post contains 4 wmv's that explain both client side and server side data access options for developers.  This was a single pesentation that I have broken up into 4 smaller units of 10-15 minutes each is about 15 Megs in size. 

Part 1 - Overview of Data Access options for SharePoint 2010 developers
Part 2 - Introduction to LINQ to SharePoint
Part 3 - More options
Part 4 - LINQ to SharePoint tips

SP2010 lists vs DB tables

Overview:  When developing using the SP2010 Server Object Model you don't have to store data in SharePoint lists, especially considering the BCS in SP2010.  This presentation video was part of a session present on data access options for Sharepoint 2010 in April 2011. It specifically looks are comparing database table vs SharePoint lists to help me decide which option to use. 
http://www.youtube.com/watch?v=8ecYVdR3a1g