c# - StructureMap 通用 Ctor 命名实例

Question

更新

我用下面的代码解决了这个问题，但这不是我要找的解决方案。 这仍然是一个更通用的解决方案的悬赏。如果我们有一个不是 int 的表或 string对于关键值，我们必须手动添加到此以使其工作。

c.For(typeof(ILogDifferencesCommand<,>)).Use(typeof(LogDifferencesCommand<,>))
                .Ctor<ILogDifferencesLogger<int>>()
                .Named(AppSettingsManager.Get("logDifferences:Target"))
                .Ctor<string>()
                .Named(AppSettingsManager.Get("logDifferences:Target"));

原始问题

我有三种类型的记录器，我在我的容器中为它们定义了命名实例:

c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesAllLogger<>))
    .Named("all");
c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesNLogLogger<>))
    .Named("nlog");
c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesDatabaseLogger<>))
    .Named("database");

LogDifferencesCommand收到 ILogDifferencesLogger<>作为它唯一的参数:

public LogDifferencesCommand(ILogDifferencesLogger<TKey> logDifferencesLogger)
{
    this.logDifferencesLogger = logDifferencesLogger;
}

如何正确配置 ILogDifferencesCommand<>根据应用程序设置获取正确的命名实例？现在我有这样的东西:

c.For(typeof(ILogDifferencesCommand<,>))
    .Use(typeof(LogDifferencesCommand<,>));

我遇到的问题是我无法拉入 Ctor<>因为我不能使用带有该签名的未绑定(bind)泛型，所以我不能使用 Named关闭方法 Ctor为此。

例如，我可以做这样的事情，但这不会影响所有可能的类型:

c.For(typeof(ILogDifferencesCommand<,>)).Use(typeof(LogDifferencesCommand<,>))
    .Ctor<ILogDifferencesLogger<int>>()
    .Named(AppSettingsManager.Get("logDifferences:Target"));

但问题是我必须处理每个 TKey系统使用的类型。

类和接口(interface)定义

public class LogDifferencesCommand<TModel, TKey> : ILogDifferencesCommand<TModel, TKey>
    where TModel : class, IIdModel<TKey>
{
    public LogDifferencesCommand(ILogDifferencesLogger<TKey> logDifferencesLogger)
    {
        this.logDifferencesLogger = logDifferencesLogger;
    }
}

public interface ILogDifferencesCommand<TModel, TKey>
    where TModel : class, IIdModel<TKey>
{
    List<LogDifference> CalculateDifferences(TModel x, TModel y);

    void LogDifferences(TModel x, TModel y, string tableName, string keyField, string userId, int? clientId);

    void RegisterCustomDisplayNameObserver(WeakReference<ICustomDisplayNameObserver<TModel>> observer);

    void RegisterCustomChangeDateObserver(WeakReference<ICustomChangeDateObserver<TModel>> observer);
}

public interface ILogDifferencesLogger<TKey>
{
    void LogDifferences(string tableName, string keyField, string userId, TKey id, List<LogDifference> differences, int? clientId);
}

原因TKey需要是因为 IIdModel界面。

Answer 1

想到的一个选项:

var loggers = new Dictionary<string, ConfiguredInstance>();
loggers.Add("all", c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesAllLogger<>)));
loggers.Add("nlog", c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesNLogLogger<>)));
loggers.Add("database", c.For(typeof(ILogDifferencesLogger<>))
    .Use(typeof(LogDifferencesDatabaseLogger<>)));
foreach (var kv in loggers) {
    // if you still need them named
    // if you only used names for this concrete scenario - you probably don't
    // so can remove it
    kv.Value.Named(kv.Key);
}
c.For(typeof(LogDifferencesCommand<>))
    .Use(typeof(LogDifferencesCommand<>))
    // add explicit instance as dependency
    .Dependencies.Add(typeof(ILogDifferencesLogger<>), loggers[AppSettingsManager.Get("logDifferences:Target")]); 

更新。正如我们在评论中发现的那样，这不适用于您在 LogDifferencesCommand 时的特定情况。有多个类型参数。出于某种原因(我认为这是一个错误)- 结构图试图创建封闭的泛型类型 ILogDifferencesLogger<> , 但这样做时 - 从 LogDifferencesCommand 传递通用类型参数.也许值得在他们的 github 上提出一个问题。您可以像这样解决它:

public class GenericTypesWorkaroundInstance : Instance
{
    private readonly Instance _target;
    private readonly Func<Type[], Type[]> _chooseTypes;
    public GenericTypesWorkaroundInstance(Instance target, Func<Type[], Type[]> chooseTypes) {
        _target = target;
        _chooseTypes = chooseTypes;
        ReturnedType = _target.ReturnedType;
    }

    public override Instance CloseType(Type[] types) {
        // close type correctly by ignoring wrong type arguments
        return _target.CloseType(_chooseTypes(types));
    }

    public override IDependencySource ToDependencySource(Type pluginType) {
        throw new NotSupportedException();
    }

    public override string Description => "Correctly close types over open generic instance";    
    public override Type ReturnedType { get; }
}

然后做

commandReg.Dependencies.Add(
    commandReg.Constructor.GetParameters().First(
        p => p.ParameterType.IsGenericType && p.ParameterType.GetGenericTypeDefinition() == typeof(ILogDifferencesLogger<>)).Name, 
        new GenericTypesWorkaroundInstance(
            loggers[AppSettingsManager.Get("logDifferences:Target")],
            // specify which types are correct
            types => types.Skip(1).ToArray()));

它有效，但我不能说我喜欢它。