如何以编程方式选择 DbConfigurationType?

本文介绍了如何以编程方式选择 DbConfigurationType?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个DbContext:

[DbConfigurationType(typeof(MySqlEFConfiguration))] public class MyDbContext : DbContext { public DbSet<MyClass> MyClasses { get; set; } }

现在，如果我希望能够根据 AppSettings 值使用另一个 DbConfigurationType 怎么办?

Now, what if I want to be able to use another DbConfigurationType, according to AppSettings value?

因此，我将 AppSettings 的值从 MySQL 更改为 MSSQL，它变为:

So that, I change AppSettings value from MySQL to MSSQL and it becomes:

[DbConfigurationType(typeof(MsSqlEFConfiguration))] public class MyDbContext : DbContext { public DbSet<MyClass> MyClasses { get; set; } }

当然，我可以创建一个工厂，并使用反射创建一个具有自定义属性的新类.但是，有没有不反思的解决方案?

Of course, I can create a factory, and use reflection to create a new class with custom attribute. However, is there a solution without reflection?

推荐答案

我已经通过继承DbConfigurationTypeAttribute解决了这个问题:

I have solved the problem by inheriting from DbConfigurationTypeAttribute:

public class BaseEfConfiguration : DbConfigurationTypeAttribute { public BaseEfConfiguration() : base(SqlConfiguration) { } public static Type SqlConfiguration { get { string databaseTypeName = ConfigurationManager.AppSettings["DatabaseType"]; switch (databaseTypeName) { case "MySQL": return typeof(MySqlEFConfiguration); case "MSSQL": return typeof(MsSqlEFConfiguration); default: throw new NotImplementedException($"No such SQL configuration type {databaseTypeName}"); } } } } [BaseEfConfiguration] public class BaseDbContext : DbContext { }