I am running into a problem and I am not sure how to solve it: How could I save a mapped class that doesn't have all fields specified? I am looking for a solution that would work with a n-tier website with an optimistic locking strategy in place.

Example: There is a class, Company. Company has several fields, id, name, website, employees, etc. This company record will exist in a core database that other modules will use. However, not all modules may care or allow for all of the traits of a Company. Module A may only allow for the name and number of employees to be modified. How can a developer for module A quickly save the new information it may have for the Company record?

Is it really a matter of having to do a database, on some tier, call to fetch the, hopefully, original graph? Is there something that I am missing?

Thanks for your help.

Is company class used by many other classes and each time there are different attributes which are important ?

I will suggest you handle this in the business layer instead of database layer.

You can ensure that all required fields for database layer are taken care of either with actual values or default values in the absence of actual value provided by the user. This can be done with the help of utility function.

A has 1,2,3,4,5 attributes

A saved with B needs only 4,5
A saved with C needs only 1,2
A saved with D needs only 1,5

Have utility function which will take care of mandatory and optional values and send populated 1,2,3,4,5 to database layer.

I think I understand what you're saying, but I am looking at a scenario of updating a Company record.

In the database there is a record, it's at version 1 status. Id: 1, Name: Jeff's Co, Website: www.jeffsco.com, Employees: 10, etc.

Module A loads up that company, and presents the Name, and Website to the user to be edited. Id is thrown into a hidden field.
User makes any relevant changes to Name and/or website, then clicks save.

What is the best way to save the updated information? Without overwriting Employees or other fields? Am I going to have to take the database hit to reload the object?