EF Core HasConstraintName

The Entity Framework Core Fluent API HasConstraintName method enables you to specify the name of the foreign key constraint for a relationship.

By default. EF Core will name a foreign key constraint according to the following pattern:

FK_<table name>_<principal table name>_<foreign key column name>

The following model will result in a foreign key constraint name of FK_Employees_Companies_CompanyId:

public class Company
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ICollection<Employee> Employees { get; set; }
}

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Company Company { get; set; }
}

The foreign key name is taken from the shadow property that will be created in the absence of a foreign key property being defined in the dependent Employee entity.

The HasConstraintName method is available on the ReferenceCollectionBuilder type, so the relationship requires configuring in order to make the method available:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Company>()
        .HasMany(c => c.Employees)
        .WithOne(e => e.Company)
        .HasConstraintName("MyFKConstraint");
}

Data Annotations

Constraint names cannot be configured with data annotation attributes.