asp.net DI系统中DbContext寄存器的多种实现方式

Question

我试图在aspnet核心DI中注册多个DbContext实现。

所以我注册了DbContext，如下图所示。

services.AddScoped(c => new CoreDbContext(c.GetService<DbContextOptions<CoreDbContext>>()));
services.AddScoped(c => new TnADbContext(c.GetService<DbContextOptions<TnADbContext>>()));
services.AddScoped<Func<DbContextType, IDbContext>>(provider => key =>
{
    switch (key)
    {
        case DbContextType.Core:
            return provider.GetService<CoreDbContext>();
        case DbContextType.TnA:
            return provider.GetService<TnADbContext>();
        case DbContextType.Payroll:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
        default:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
    }
});

所以在仓库中，我试图请求如下的实例

private readonly IDbContext _context;
public Repository(Func<DbContextType, IDbContext> resolver)
{
    _context = resolver(DbContextType.TnA);
}

但是当我运行这个应用程序时，它却抛出了一个异常，如下所示

有些服务无法被构造（验证服务描述符'ServiceType.TestController'时出错。Web.Area.TestController Lifetime: Transient ImplementationType.Web.Areas.TestController': 在验证服务描述符'ServiceType: Web.Areas.TestController Lifetime: Transient ImplementationType: Web.Areas.TestController"。 当试图激活'Service.InterfaceService'时，无法解析'Data.IDbContext'类型的服务。)

基本上几乎所有的服务和控制器都在抱怨同一个问题。那么缺失的部分是什么呢？

更新

其实我在注册DB上下文时做了一些修改，现在可以了。

services.AddScoped<Func<DbContextType, IDbContext>>(provider => key =>
{
    switch (key)
    {
        case DbContextType.Core:
            return new CoreDbContext(provider.GetService<DbContextOptions<CoreDbContext>>());
        case DbContextType.TnA:
            return new TnADbContext(provider.GetService<DbContextOptions<TnADbContext>>());
        case DbContextType.Payroll:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
        default:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
    }
});

Answer 1

所以我想出了一个解决方案，注册Dbconfigs，如下所示

services.AddScoped<Func<DbContextType, IDbContext>>(provider => key =>
{
    switch (key)
    {
        case DbContextType.Core:
            return new CoreDbContext(provider.GetService<DbContextOptions<CoreDbContext>>());
        case DbContextType.TnA:
            return new TnADbContext(provider.GetService<DbContextOptions<TnADbContext>>());
        case DbContextType.Payroll:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
        default:
            throw new ArgumentOutOfRangeException(nameof(key), key, null);
    }
});

并确保IDbContext不注入任何服务，而不是你可以尝试以下方法

private readonly IDbContext _context;

public InterfaceService(Func<DbContextType, IDbContext> resolver)
{
    _context = resolver(DbContextType.TnA);
}

DbContext类型将是一个包含我需要注入的DB上下文类型的枚举。