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Entity Framework - Hybrid Code First

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Let's talk about an interesting subject related to Entity Framework (EF). When you are using EF there are different mechanism to map your model:
  • Code First - we write the code first and the DB is generated automatically based on the code
  • Database First - we define the DB structure and POCO entities are created automatically
  • Model First - we design the model in a 'nice' designer. This designer will generate the classes and the database model
All of them are perfect and works great. Based on our needs, preferences and team skills we can decide to go with an approach or another, but in the end we will end up with the same thing. I will follow up later on with a different post where I will compare them.

Now, let's talk about different scenarios that is used by people. I saw in a lot of implementation where people are afraid of Code First or Model First. Because of this I realize that most of them are using a hybrid solution that I called Hybrid Code First.

Why I called Hybrid Code First? 
Well, people don't trust EF to generate the database schema. Because of this they are defining the model in the code as classes (POCO). Once this is done, they are defining the database schema - tables, indexes, keys, the relationship between entities. 
Once this step is done, they are defining the mapping between their classes (POCO) and database schema using Fluent API. In this way they are connecting each C# entity model to each table, column or key.

Is this a good approach?
Well...there is no the right answer. This approach it is used because people don't trust EF enough. People don't trust that EF can generate a database schema good enough. Based on this fears they combine Code First with Database First using Fluent API. 
This way they have full control to database schema and also to the model (C# entities). 
Of course, because of this versioning needs to be made manually, but they don't trust out of the box versioning of Code First, even if with EF 4.1 version, it works pretty great.

This is another approach to define and manage the entities model. Even if it is more time consuming, it offers a safety nest for developing team. Offering them control for both part (DB and Code).  
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Comments

  1. tudor_turcuJune 11, 2015 at 7:21 PM

    We are using exactly this model - and not because we don't trust EF to generate the database create/update scripts - it's because very often the DB schema can't be inferred only from the mappings.

    An example:
    - all C# classes are mapped to database views, that perform (custom) queries over the DB tables - how could EF by itself generate such a database? :)

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