Using Entity Framework Code First with an existing database – Part 1

If you do any sort of .NET development using a relational database then chances are pretty good that you’d use Entity Framework as your ORM (object-relational mapping) technology – and in particular Entity Framework Code First since that’s the Entity Framework approach that Microsoft appears to favor going forward.

So what exactly is Entity Framework Code First?

The Entity Framework Code First approach allows us to write Plain Old CLR Objects (POCOs) for our data models and then persist them in a data store using the DbContext class. Model classes are much cleaner this way and they are developer-friendly – gone are the days of complex (and often buggy) XML .edmx files which were needed in the past with Entity Framework in order to describe and map the model layer to the physical data storage layer.

Below is a simple example of such a POCO class:

We can see here that certain attributes are used to describe some of the physical properties of the SQL table and its columns. Entity Framework Code First makes heavy use of conventions in order to determine what to expect at the physical data storage layer given a particular POCO class that describes the model.

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