- 1-0:1
1 student to 0:1 StudentAddress.
- Model classes:
public class Student
{
public int Id { get; set; }
public string LastName { get; set; }
public string FirstMidName { get; set; }
public StudentAddress Address { get; set; }
}
public class StudentAddress
{
public int StudentId { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string City { get; set; }
public string State { get; set; }
public string Zip { get; set; }
public Student Student { get; set; }
}
- Mappings:
public class StudentMap : IEntityTypeConfiguration<Student>
{
public void Configure(EntityTypeBuilder<Student> builder)
{
builder.ToTable(nameof(Student));
builder.HasKey(x => x.Id);
}
}
public class StudentAddressMap : IEntityTypeConfiguration<StudentAddress>
{
public void Configure(EntityTypeBuilder<StudentAddress> builder)
{
builder.ToTable(nameof(StudentAddress));
builder.HasKey(u => u.StudentId); // StudentAddress.StudentId is primary key
builder.HasOne(u => u.Student)
.WithOne(b => b.Address)
.HasForeignKey<StudentAddress>(b => b.StudentId); // StudentAddress.StudentId is foreign key to Student.Id, too.
}
}
public class SchoolContext : DbContext
{
public SchoolContext (DbContextOptions<SchoolContext> options)
: base(options)
{
}
public DbSet<Student> Students { get; set; }
public DbSet<StudentAddress> StudentAddresses { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.ApplyConfiguration(new StudentMap());
modelBuilder.ApplyConfiguration(new StudentAddressMap());
}
}
- Generated tables:
CREATE TABLE [Student] (
[Id] int NOT NULL IDENTITY,
[LastName] nvarchar(max) NULL,
[FirstMidName] nvarchar(max) NULL,
CONSTRAINT [PK_Student] PRIMARY KEY ([Id])
);
CREATE TABLE [StudentAddress] (
[StudentId] int NOT NULL,
[AddressLine1] nvarchar(max) NULL,
[AddressLine2] nvarchar(max) NULL,
[City] nvarchar(max) NULL,
[State] nvarchar(max) NULL,
[Zip] nvarchar(max) NULL,
CONSTRAINT [PK_StudentAddress] PRIMARY KEY ([StudentId]),
CONSTRAINT [FK_StudentAddress_Student_StudentId] FOREIGN KEY ([StudentId]) REFERENCES [Student] ([Id]) ON DELETE CASCADE
);
2. 0:1-m
- 1 Auther to 1:m Book.
public class SampleContext : DbContext{ public DbSet<Book> Books { get; set; } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Author>() .HasMany(a => a.Books) .WithOne(b => b.Author); }}
public class Author{ public int AuthorId { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public ICollection<Book> Books { get; set; }}
public class Book{ public int BookId { get; set; } public string Title { get; set; } public Author Author { get; set; }}
public class SampleContext : DbContext{ public DbSet<Book> Books { get; set; } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Author>() .HasMany(a => a.Books) .WithOne(b => b.Author); }}
public class Author{ public int AuthorId { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public ICollection<Book> Books { get; set; }}
public class Book{ public int BookId { get; set; } public string Title { get; set; } public Author Author { get; set; }}3. 1-1:m
- 1 Auther to 0:m Book.
Same as 1-0:m except IsRequired() is added in relation definition as below:
public class SampleContext : DbContext{public DbSet<Book> Books { get; set; }protected override void OnModelCreating(ModelBuilder modelBuilder){modelBuilder.Entity<Author>().HasMany(a => a.Books).WithOne(b => b.Author).IsRequired();}}
