EF Code-First 學習之旅 Fluent API

Mappings	To Database
Model-wide Mapping	Set default Schema Set Custom Convetions
Entity Mapping	To Single or Multiple Tables and Schema To Complex type Inheritance Hierarchies
Property Mapping	To Column, Column Name, Column Type, Nullable or Not Null Column, Column size, Columns Order To Concurrency column To Foreign key column To configure relationships

public class SchoolContext: DbContext 
{
    public SchoolDBContext(): base() 
    {
    }

    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
        
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Configure domain classes using modelBuilder here

        base.OnModelCreating(modelBuilder);
    }
}

 

在OnModelCreating方法中配置Fluent API

Code First配置優先順序為：Fluent API > DataAnnotations > default conventions

EntityTypeConfiguration

EntityTypeConfiguration是一個重要的類，

Method Name	Return Type	Description
HasKey<TKey>	EntityTypeConfiguration	為實體類配置主鍵
HasMany<TTargetEntity>	ManyNavigationPropertyConfiguration	配置多對多的關系
HasOptional<TTargetEntity>	OptionalNavigationPropertyConfiguration	配置從這個實體中可選的關系，這個實體的實例可以沒有和關系就保存到數據庫中，數據庫中的外鍵可為nullable
HasRequired<TTargetEntity>	RequiredNavigationPropertyConfiguration	配置從這個實體中必須的關系，實體的實例如果沒有指定關系不能保存在數據庫中，數據庫外鍵為non-nullable
Ignore<TProperty>	Void	排除實體的屬性不映射到數據庫中
Map	EntityTypeConfiguration	允許與此實體類型映射到數據庫架構的高級配置有關。
Property<T>	StructuralTypeConfiguration	配置在該類型上定義的結構屬性
ToTable	Void	配置此實體類型映射到的表名。

 

 

Entity Mappings

 

public class Student
{
    public Student()
    { 
        
    }
    public int StudentID { get; set; }
    public string StudentName { get; set; }
    public DateTime? DateOfBirth { get; set; }
    public byte[]  Photo { get; set; }
    public decimal Height { get; set; }
    public float Weight { get; set; }
        
    public Standard Standard { get; set; }
}
    
public class Standard
{
    public Standard()
    { 
        
    }
    public int StandardId { get; set; }
    public string StandardName { get; set; }
    
    public ICollection<Student> Students { get; set; }
   
    }

 

 

 

Configure Default Schema

 

public class SchoolContext: DbContext 
{
    public SchoolDBContext(): base() 
    {
    }

    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
        
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Configure default schema
        modelBuilder.HasDefaultSchema("Admin");
    }
}

 

 配置實體映射到表

namespace CodeFirst_FluentAPI_Tutorials
{
        
    public class SchoolContext: DbContext 
    {
        public SchoolDBContext(): base() 
        {
        }

        public DbSet<Student> Students { get; set; }
        public DbSet<Standard> Standards { get; set; }
        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
                //Configure default schema
            modelBuilder.HasDefaultSchema("Admin");
                    
            //Map entity to table
            modelBuilder.Entity<Student>().ToTable("StudentInfo");
            modelBuilder.Entity<Standard>().ToTable("StandardInfo","dbo");

        }
    }
}

 

 

配置實體到多個表中

namespace CodeFirst_FluentAPI_Tutorials
{
        
    public class SchoolContext: DbContext 
    {
        public SchoolDBContext(): base() 
        {
        }

        public DbSet<Student> Students { get; set; }
        public DbSet<Standard> Standards { get; set; }
        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Student>().Map(m =>
            {
                m.Properties(p => new { p.StudentId, p.StudentName});
                m.ToTable("StudentInfo");

            }).Map(m => {
                m.Properties(p => new { p.StudentId, p.Height, p.Weight, p.Photo, p.DateOfBirth});
                m.ToTable("StudentInfoDetail");

            });

            modelBuilder.Entity<Standard>().ToTable("StandardInfo");

        }
    }
}

 

 

 

 

Property Mappings 

public class SchoolContext: DbContext 
{
    public SchoolDBContext(): base() 
    {
    }

    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
        
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Configure primary key
        modelBuilder.Entity<Student>().HasKey<int>(s => s.StudentKey);
        modelBuilder.Entity<Standard>().HasKey<int>(s => s.StandardKey);

        //Configure composite primary key
        modelBuilder.Entity<Student>().HasKey<int>(s => new { s.StudentKey, s.StudentName }); 
    }
}

 

 

 

public class SchoolContext: DbContext 
{
    public SchoolDBContext(): base() 
    {
    }

    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
        
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Configure Column
        modelBuilder.Entity<Student>()
                    .Property(p => p.DateOfBirth)
                    .HasColumnName("DoB")
                    .HasColumnOrder(3)
                    .HasColumnType("datetime2");
    }
}

 

 

 

 

配置nullable和non-nullable

namespace CodeFirst_FluentAPI_Tutorials
{
        
    public class SchoolContext: DbContext 
    {
        public SchoolDBContext(): base() 
        {
        }

        public DbSet<Student> Students { get; set; }
        public DbSet<Standard> Standards { get; set; }
        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
                //Configure Null Column
            modelBuilder.Entity<Student>()
                    .Property(p => p.Heigth)
                    .IsOptional();
                        
                //Configure NotNull Column
                modelBuilder.Entity<Student>()
                    .Property(p => p.Weight)
                    .IsRequired();
        }
    }
}

 

配置列的長度

namespace CodeFirst_FluentAPI_Tutorials
{
        
    public class SchoolContext: DbContext 
    {
        public SchoolDBContext(): base() 
        {
        }

        public DbSet<Student> Students { get; set; }
        public DbSet<Standard> Standards { get; set; }
        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //Set StudentName column size to 50
            modelBuilder.Entity<Student>()
                    .Property(p => p.StudentName)
                    .HasMaxLength(50);
                        
            //Set StudentName column size to 50 and change datatype to nchar 
            //IsFixedLength() change datatype from nvarchar to nchar
            modelBuilder.Entity<Student>()
                    .Property(p => p.StudentName)
                    .HasMaxLength(50).IsFixedLength();
                        
            //Set size decimal(2,2)
                modelBuilder.Entity<Student>()
                    .Property(p => p.Height)
                    .HasPrecision(2, 2);
        }
    }
}

 

配置並發列

namespace CodeFirst_FluentAPI_Tutorials
{
        
    public class SchoolContext: DbContext 
    {
        public SchoolDBContext(): base() 
        {
        }

        public DbSet<Student> Students { get; set; }
        public DbSet<Standard> Standards { get; set; }
        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            //Set StudentName as concurrency column
            modelBuilder.Entity<Student>()
                    .Property(p => p.StudentName)
                    .IsConcurrencyToken();
        }
    }
}

 

也可以用IsRowVersion()來配置byte[]數組