Fluent API meaning in ASP.NET MVC when using Entity Framework - entity-framework

Question

I am learning ASP.NET MVC. And In order to create PK and FK I have added some code in models in .cs file as below
public class Courses
{
public int CourseID { get; set; }
[Key]
public string CourseName { get; set; }
public string Description { get; set; }
public int Duration { get; set; }
public virtual ICollection<Instructors> Instructors { get; set; }
}
public class Instructors
{
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string CourseName { get; set; }
[ForeignKey("CourseName")]
public virtual Courses Courses { get; set; }
}
My question is then what is the significance of Fluent API. I have successfully created PK and FK using above code in model. Then what is Fluent API and why it is needed?

Answer 1

Entity framework Fluent Api is an alternative way to define database schema using Entity framework Code First approach. The syntax that you used in your question uses data annotations which is other common approach.
The major advantage of FluentApi is that you don't have to have actual access to your model classes in order to decorate them. For example when you have your models in separate assembly decorating them with annotations is simply impossible. On the other hand by using EF FluentAPI you can easily do it with something like:
modelBuilder.Entity<Courses>().HasKey(c => c.CourseID);
At the bottom line both approaches generate exactly the same database schema.
So if you prefer to use data annotations and your project structure allows it, you can use it without any doubts. In those cases when you can not use the data annotations approach and you still want to use Code First approach, FluentApi is the right way to look at.