Entity Framework : Object is null but the foreign key isn't

Question

I'm learning .NET Core and EF Core, but I already have an issue.

I created my code from scratch,

Here's my code :

public class DBContext : DbContext
{
    public DbSet<Muscle> Muscle { get; set; }
    public DbSet<Exercice> Exercice { get; set; }
}
public class Muscle
{
    [Key]
    public int id { get; set; }
    public string nom { get; set; }

    public virtual ICollection<Exercice> Exercices { get; set; }
}
public class Exercice
{
    [Key]
    public int id { get; set; }
    public string libelle { get; set; }

    public int MuscleId { get; set; }
    public virtual Muscle Muscle { get; set; }
}

When I try to get my first "Exercice", his "MuscleId" is "1" but his "Muscle" is null... And if I try to get my first "Muscle", "Exercices" is null aswell ...

Is there something I have to do to make this work? Thanks

Answer 1

Your Muscle class primary key should match foreign key on Exercise class. Like this.

public class Muscle
{
    [Key]
    public int MuscleId { get; set; }
    public string nom { get; set; }
    public virtual ICollection<Exercice> Exercices { get; set; }
}

Or use [ForeignKey] Attribute. You can read more here. http://www.entityframeworktutorial.net/code-first/foreignkey-dataannotations-attribute-in-code-first.aspx