如何創建自定義ReusableDbContext

Question

三類：

• CustomDbContext
• ReusableContext
• 的DbContext

關係：

• ReusableContext：的DbContext
• CustomDbContext：ReusableContext

代碼：

public class ReusableDbContext : DbContext 
{ 
    public ReusableDbContext() 
     : base("name = myConnectionString") 
    { 
     Database.SetInitializer＜ReusableDbContext＞(new 
MigrateDatabaseToLatestVersion＜ReusableDbContext, ReusableMigrationsConfiguration＞()); 
    } 

    public DbSet＜ReusableTable＞ ReusableTables{ get; set; } 
} 

public class ReusableMigrationsConfiguration : DbMigrationsConfiguration＜ReusableDbContext＞ 
{ 
    public ReusableMigrationsConfiguration() 
     : base() 
    { 
     AutomaticMigrationsEnabled = true; 
     AutomaticMigrationDataLossAllowed = true; 
    } 

    protected override void Seed(ReusableDbContext context) 
    { 
     //ReusableMigrationsConfiguration Seed Logic here 
     // this Seed method is never called ----------- The Problem here! 
    } 
} 

然後我嘗試重用ReusableContext這樣的：

• ReusableTable和CustomTable：項目運行後

  public class CustomDbContext : ReusableDbContext 
  { 
      public CustomDbContext() 
       : base() 
      { 
       Database.SetInitializer＜CustomDbContext＞(new 
  MigrateDatabaseToLatestVersion＜CustomDbContext, CustomMigrationsConfiguration＞()); 
      } 
  
      public DbSet＜CustomTable＞ CustomTables{ get; set; } 
  } 
  
  public class CustomMigrationsConfiguration : DbMigrationsConfiguration＜CustomDbContext＞ 
  { 
      public CustomMigrationsConfiguration() 
       : base() 
      { 
       AutomaticMigrationsEnabled = true; 
       AutomaticMigrationDataLossAllowed = true; 
      } 
  
      protected override void Seed(CustomDbContext context) 
      { 
       //CustomMigrationsConfiguration Seed Logic 
       // this Seed method is called, no problem here 
      } 
  } 
  

  被創建

• CustomMigrationsConfiguration的種子方法被調用並確定
• 但是，ReusableMigrationsConfiguration的種子方法不被稱爲--------出了什麼問題？

Answer 1

問題解決了，這裏是解決方案。

類別：

• CustomDbContext，CustomMigrationsConfiguration
• ReusableContext，ReusableMigrationsConfiguration
• 的DbContext

關聯：

• ReusableContext：DbConte XT
• ReusableMigrationsConfiguration ：DbMigrationsConfiguration 其中TContext：ReusableContext
• CustomDbContext：ReusableContext
• CustomMigrationsConfiguration：ReusableMigrationsConfiguration

代碼：

public class ReusableDbContext : DbContext 
{ 
    public ReusableDbContext() 
     : base("name = myConnectionString") 
    { 
     Database.SetInitializer＜ReusableDbContext＞(new 
MigrateDatabaseToLatestVersion＜ReusableDbContext, ReusableMigrationsConfiguration＞()); 
    } 

    public DbSet＜ReusableTable＞ ReusableTables{ get; set; } 
} 

public class ReusableMigrationsConfiguration＜TContext＞ : DbMigrationsConfiguration＜TContext＞ where TContext : ReusableDbContext 
{ 
    public ReusableMigrationsConfiguration() 
     : base() 
    { 
     AutomaticMigrationsEnabled = true; 
     AutomaticMigrationDataLossAllowed = true; 
    } 

    protected override void Seed(TContext context) 
    { 
     //ReusableMigrationsConfiguration Seed Logic here 
     // is called and OK now. 
    } 
} 

現在我們可以像這樣重用ReusableContext：

public class CustomDbContext : ReusableDbContext 
{ 
    public CustomDbContext() 
     : base() 
    { 
     Database.SetInitializer＜CustomDbContext＞(new 
MigrateDatabaseToLatestVersion＜CustomDbContext, CustomMigrationsConfiguration＞()); 
    } 

    public DbSet＜CustomTable＞ CustomTables{ get; set; } 
} 

public class CustomMigrationsConfiguration : ReusableMigrationsConfiguration＜CustomDbContext＞ 
{ 
    public CustomMigrationsConfiguration() 
     : base() 
    { 
     AutomaticMigrationsEnabled = true; 
     AutomaticMigrationDataLossAllowed = true; 
    } 

    protected override void Seed(CustomDbContext context) 
    { 
     base.Seed(context); 



     //CustomMigrationsConfiguration Seed Logic 
     // this Seed method is called and OK 
    } 
} 

運行的項目後：

• ReusableTable和CustomTable創建;
• CustomMigrationsConfiguration的種子方法被調用並確定;
• ReusableMigrationsConfiguration的Seed方法也被調用，也可以。

所有事情似乎現在要罰款:)

Answer 2

public class CustomDbContext : **ReusableDbContext** 
{ 
    public CustomDbContext() 
     : base() 
    { 
     Database.SetInitializer＜CustomDbContext＞(new 
MigrateDatabaseToLatestVersion＜CustomDbContext, CustomMigrationsConfiguration＞()); 
    } 

    public DbSet＜CustomTable＞ CustomTables{ get; set; } 
} 

做到這一點，將工作

public class CustomMigrationsConfiguration : DbMigrationsConfiguration＜CustomDbContext＞ 
{ 
    public ReusableMigrationsConfiguration() 
     : base() 
    { 
     AutomaticMigrationsEnabled = true; 
     AutomaticMigrationDataLossAllowed = true; 
    } 

    protected override void Seed(CustomDbContext context) 
    { 
     //CustomMigrationsConfiguration Seed Logic 
     // this Seed method is called, no problem here 
    } 
}