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Code First and Data First Approaches in Entity Framework

  • 3 min
  • Beginner

As we saw in the introduction, in Entity Framework there are two main approaches for configuring and managing a database:

  • Data-First: We create the database first.
  • Code-First: We create the classes first.

These methods define the workflow. Specifically, how we are going to generate and synchronize the application classes and the database schema.

The first decision we will have to make in an Entity Framework project is whether we want to work with one or the other.

You must choose one or the other. They are not compatible, nor something we can change in the middle of the project (at least not easily).

In general, the more “modern” option is Code First. But, in reality, both have their advantages, disadvantages, and specific use cases.

In this article, we are going to compare both approaches, their workflows, and when it is more convenient to use them 👇.

What is Data-First?

The Data-First (or Database-First) approach means starting development from an already existing database.

With Data-First,

  • We manually create 🖐 the database.
  • We automatically generate 🤖 the application classes.

This approach is useful when working with a database that has already been designed or in projects where the database structure is imposed or managed by a separate team.

Steps of Data-First in Entity Framework Core

  1. Define the database: The database structure, with its tables, relationships, and constraints, must be previously defined.
  2. Generate the model: Entity Framework Core allows you to automatically create the C# classes from the database schema using the Scaffold-DbContext command.
  3. Automatic mapping: The ORM generates the necessary classes and automatically establishes the mappings between the database and the objects in C#.

What is Code-First?

The Code-First approach is the “opposite case”. It allows us to first define the models and classes in the code, and then automatically generate or update the database based on these models.

With Code-First,

  • We manually create 🖐 the application classes
  • We automatically generate 🤖 the database.

With Code-First, the C# code is what defines the database structure. This gives us greater control over the classes, relationships, and constraints of the database.

Steps of Code-First in Entity Framework Core

  1. Define the classes in C#: Entities and their relationships are created using classes and properties, utilizing data annotations or configurations in the code.
  2. Create migrations: With the Add-Migration command, the necessary migrations are generated to create or update the database schema based on changes in the classes.
  3. Update the database: When executing the Update-Database command, the migrations are applied to the database, synchronizing its structure with the class model.

At first, it’s a bit dizzying that someone “tinkers” with the database automatically.

Don’t worry, it’s normal, it has happened to all of us (and still does).

When to use Data-First and when to use Code-First?

So, when to use one or the other? In general, it will depend on the context, the type of project, and even the team’s preferences.

But, in general,

  • Data-First is ideal for projects where the database already exists and has a defined structure.
  • Code-First is preferable for new projects or those where the development team has full control over the data model and the evolution of the database.
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