Question

三课：

CustomDbContext
ReusableContext
的DbContext

关联：

ReusableContext：DbContext
CustomDbContext：ReusableContext

代码：

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!
    }
}

然后我尝试像这样重用ReusableContext：

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

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

public class CustomMigrationsConfiguration : 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
    }
}

运行项目后

：

创建了ReusableTable和CustomTable
调用CustomMigrationsConfiguration的种子方法，然后单击“确定”
但是，没有调用ReusableMigrationsConfiguration的种子方法--------有什么问题？

Answer 1

问题解决了，这是解决方案。

班级：

CustomDbContext，CustomMigrationsConfiguration
ReusableContext，ReusableMigrationsConfiguration
的DbContext

关联：

ReusableContext：DbContext
ReusableMigrationsConfiguration ：DbMigrationsConfiguration 其中TContext：ReusableContext
CustomDbContext：ReusableContext
CustomMigrationsConfiguration：ReusableMigrationsConfiguration

代码：

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.
    }
}

现在我们可以像这样重用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
    }
}

运行项目后

：

创建了ReusableTable和CustomTable;
调用CustomMigrationsConfiguration的种子方法，然后单击“确定”;
ReusableMigrations的种子方法调用配置也可以。

现在一切似乎都没事了。）

Answer 2

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

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

这样做会起作用

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
    }
}

如何创建自定义可重用DbContext

2 个答案: