SharePoint 2010 - Customizing the rendering and behavior of a List field

In my SharePoint List, I have an "Employee" column that is a User type field. I would like to add some custom Business Logic to the processing of this field. Currently, when the user adds a row, I check to see if the user is an Employee or a Manager and then change the behavior on this column accordingly. I do this by statically rendering the field in my custom "ListForm Rendering Template", just before my custom ListFieldIterator. I simply use a standard SharePoint FormField (and FormLabel) control. In the markup of the FormField control, I specify the FieldName (Employee) and an event handler for the Load event. In this Load event, I will check to see if the current user is an Employee or Manager (using two different SharePoint groups). If the user is an Employee I set the value of the field to the current user (this part works perfectly). I also want to change the field so it can't be modified. I thought I might be able to just change the ControlMode on the field (in the code of the OnLoad Event Handler) to Display, but for some reason this has no effect. The field still renders with the full, people picker editor. Am I not changing the fields control mode soon enough? Or is this simply not the correct approach? The other logic I want to put in is if the user is a Manager, I would like to allow that user to select the person from a list (SharePoint group) of Employees. It may be easier to just use the people picker and limit the selectable users to that group. (I think I can do this with the SelectionGroup property.) Although, it would be bette开发者_如何学Gor if I could just provide a dropdownlist of users, which I could possibly do with a hidden dropdownlist that I would show and event handlers that I could use (handle event selectedindexchanged) to pull the value selected and populate the (now hidden) Employee (user) field. Does this approach make sense? Assuming all that will work, the real difficulty I am having is with changing the ControlMode (rendering) on the field (when the user is an employee) to a label or some kind of read only control, which is how that field renders when viewing the row, which is why I think if I can just trick the control into thinking it is in Display mode then it should work perfectly!

I am still learning SharePoint, but I am very proficient in ASP .Net. This is why I would like to keep my customizations in this Custom Rendering Template, using code behind and leverage my existing skill set as much as properly.

Any thoughts, opinions or advice? Does anyone know why I can't get the column to switch the "Control Mode"?

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I do not think that I fully understand your scenario. Some code samples could help.

But anyway it sounds like you want some heavy customizations of the user field. In that case you might want to have a look at creating a custom field with all its advantages and disadvantages. Have a look at MSDN: http://msdn.microsoft.com/en-us/library/gg132914.aspx

Another option might be - in case you do not want to re-use this column in many list definitions - that you can get away with your custom rendering template and create a custom create/edit form where you implement the specific edit behaviour for the field (plain ASP.NET with some SharePoint controls). Here is a nice walk-through on how to grab a custom edit form from SharePoint designer: http://community.bamboosolutions.com/blogs/sharepoint-2010/archive/2011/05/12/sharepoint-2010-cookbook-how-to-create-a-customized-list-edit-form-for-development-in-visual-studio-2010.aspx

I hope this helps. Kr., Bernd.