Entity Framework Database first How to alter entities to make them derive from a base class

Question

I have a database already full of tables with data in them. What I have seen is that all tables have 5 columns in common:

• Id-long, key
• IsDeleted, bit
• DateDeleted, SmallDatetime
• LastUpdated, SmallDatetime
• LastUpdatedUser, nvarchar

Now, there are some common operations that are done based on those fields which currently are replicated everywhere

What I want is to create a base class containing just these common attributes and the methods done to them and make every other entity derive from this.

I don't need or want to have this base entity on the database per se, this is just something I want to help the coding part.

The issue is this is Database first, I cannot alter the database so all I have to work with are the POCO classes and the EDMX.

How can i achieve this?

Answer 1

What you are looking for is something similar to TPH (http://msdn.microsoft.com/en-us/data/jj618292.aspx)

I don't think this will work for you however, as you have multiple existing tables.

One of the possible solutions is:

1. Create a base class called "BaseModel" (or something like that)
2. Add those properties as abstracts to force them to be overridden
3. Create a method in that base class to populate those fields, or create a helper which takes BaseModel, IsDeleted,LastUpdated, LastUpdatedUser as a parameter and update the model.
4. Extend the partial classes generated by the model.tt file and inherit from the BaseModel class.

Thanks, Dave