Net核心:用变量类型声明新的DbContext

Question

如何声明DbContextOptionsBuilder，其中DbContext存储在变量中(在本例中，dbContext的实名为"OnlineShoppingStore“，但存储在下面的两个变量中)。

var dbContextType = dbContextAssembly.GetTypes().Where(d => d.BaseType.Name == "DbContext").First();
var businessDbContext = Activator.CreateInstance(dbContextType) as DbContext;
DbContextOptionsBuilder optionsBuilder = new DbContextOptionsBuilder();

// Attempting Line Below
var options = new DbContextOptionsBuilder<dbContextType>().UseInMemoryDatabase(databaseName: "Test").Options;

错误: dbContextType是一个变量，但被用作类型。

的最终目标是声明一个新的DbContext，给定来自上面程序集的类型。

示例：

var onlineStoreContext = new OnlineStoreContext(options)

Answer 1

你快到了。可以使用以下方法创建泛型类型的实例：

Type dbContextType = typeof(MyDbContext);
// 1st get type of Generic object
Type dbContextOptionsBuilderType = typeof(DbContextOptionsBuilder<>);
// 2nd call "MakeGenericType" method by passing the "T" type
Type dbContextOptionsBuilderGenericType = dbContextOptionsBuilderType.MakeGenericType(dbContextType);
// 3rd create an instance by using "Activator.CreateInstance"
DbContextOptionsBuilder dbContextOptionsBuilderInstance = Activator.CreateInstance(dbContextOptionsBuilderGenericType) as DbContextOptionsBuilder;

DbContextOptions dbContextOptions = dbContextOptionsBuilderInstance.UseInMemoryDatabase(databaseName: "Test").Options;

"How to use local variable as a type? Compiler says "it is a variable but is used like a type"“是最初的解决方案。