17.翻译系列：将Fluent API的配置迁移到单独的类中【EF 6 Code-First系列】

时间 2019-11-06

标签翻译系列 fluent api 配置迁移单独 code 繁體版

原文原文链接

原文连接：https://www.entityframeworktutorial.net/code-first/move-configurations-to-seperate-class-in-code-first.aspxhtml

EF 6 Code-First系列文章目录：数据库

你在前面的章节中已经看到，咱们在OnModelCreating()方法中，使用Fluent API为全部的实体类进行配置。然而这样作，当配置的实体类不少的时候，就变得很难维护了。EF 6 容许你单独为每一个实体，在单独的类中进行配置。app

看看下面咱们在Student实体中配置的代码：ide

public class SchoolDBContext: DbContext { public SchoolDBContext(): base() { } public DbSet<Student> Students { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Student>().ToTable("StudentInfo"); modelBuilder.Entity<Student>().HasKey<int>(s => s.StudentKey); modelBuilder.Entity<Student>() .Property(p => p.DateOfBirth) .HasColumnName("DoB") .HasColumnOrder(3) .HasColumnType("datetime2"); modelBuilder.Entity<Student>() .Property(p => p.StudentName) .HasMaxLength(50); modelBuilder.Entity<Student>() .Property(p => p.StudentName) .IsConcurrencyToken(); modelBuilder.Entity<Student>() .HasMany<Course>(s => s.Courses) .WithMany(c => c.Students) .Map(cs => { cs.MapLeftKey("StudentId"); cs.MapRightKey("CourseId"); cs.ToTable("StudentCourse"); }); } }

你能够将上面的配置部分，移动到单独的类中，这个类继承自EntityTypeConfiguration<TEntity>。看看下面的StudentEntityConfigurations类，它包含全部Student类的配置：函数

public class StudentEntityConfiguration: EntityTypeConfiguration<Student> { public StudentEntityConfiguration() { this.ToTable("StudentInfo"); this.HasKey<int>(s => s.StudentKey); this.Property(p => p.DateOfBirth) .HasColumnName("DoB") .HasColumnOrder(3) .HasColumnType("datetime2"); this.Property(p => p.StudentName) .HasMaxLength(50); this.Property(p => p.StudentName) .IsConcurrencyToken(); this.HasMany<Course>(s => s.Courses) .WithMany(c => c.Students) .Map(cs => { cs.MapLeftKey("StudentId"); cs.MapRightKey("CourseId"); cs.ToTable("StudentCourse"); }); } }

正如上面的代码你所看到的那样，咱们将全部Student的配置部分，放到了StudentEntityConfiguration类的构造函数中。测试

如今你须要使用Fluent API添加这个配置类：ui

public class SchoolDBContext: DbContext { public SchoolDBContext(): base() { } public DbSet<Student> Students { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // Moved all Student related configuration to StudentEntityConfiguration class
        modelBuilder.Configurations.Add(new StudentEntityConfiguration()); } }

因此你能够，使用不少的单独的配置类，这样就使得代码，更加可读，更加可维护。this