Creating Models and Migrations in Entity Framework Code First Approach
Introduction
Entity Framework (EF) is an open-source object-relational mapper (ORM) that enables .NET developers to work with relational data using domain-specific objects. EF Code First allows developers to create a model using classes and then generate a database from it. In this guide, we will discuss how to create models and migrations in the EF Code First approach.
Creating Models in EF Code First
To create a model in EF Code First, we need to create a class that represents the table in the database. We can then add properties to the class, which will represent the columns in the table. Here is an example of a model class:
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public string Address { get; set; }
}
The Id property acts as the primary key and will be automatically configured as such. We can also add relationships between the models, such as one-to-many or many-to-many, by adding navigation properties to the classes.
Creating Migrations in EF Code First
Once we have created the model classes, we can generate a database from them using EF Code First Migrations. To enable migrations, we need to open the Package Manager Console and run the command Enable-Migrations. This will create a Migrations folder in the project. We can then add a new migration by running the command Add-Migration MigrationName. This will create a new migration class with an Up and Down method. The Up method will contain the code to create the tables and columns in the database, while the Down method will contain the code to delete the tables and columns.
We can then run the command Update-Database to apply the migrations and create the database.
Tips
- Remember to add the
Idproperty to each model class, as it will be used as the primary key. - Make sure to add navigation properties to the model classes to represent relationships between them.
- Don’t forget to run the
Enable-Migrationscommand before adding a migration. - Always use descriptive names for the migrations, as it will help you keep track of the changes you have made.
- When you are ready to apply the migrations, remember to run the
Update-Databasecommand.
Conclusion
In this guide, we discussed how to create models and migrations in the EF Code First approach. We looked at how to create model classes and add properties to them, as well as how to enable and add migrations. We also included some tips to help you remember important steps in the process.