c# – 如何使用泛型创建Fluent界面

我想创建一个流畅的界面,可以像这样使用：

void Main() {
    ModelStateMappings.MapDomainModel<Book>().MapViewModel<BookViewModel>()
        .Properties(book => book.Author, vm => vm.AuthorsName)
        .Properties(book => book.Price, vm => vm.BookPrice);

    ModelStateMappings.MapDomainModel<Store>().MapViewModel<StoreViewModel>()
        .Properties(store => store.Owner, vm => vm.OwnersName)
        .Properties(store => store.Location, vm => vm.Location);
}

我希望最终得到一个看起来像这样的集合：

static class ModelStateaMappings {
    private static IList<ModelMappings> mappings;
    // other methods in here to get it working
}

class ModelMappings {
    public Type DomainModelType {get;set;}
    public Type ViewModelType {get;set;}
    public IList<PropertyMapping> PropertyMappings {get;set;}
}

class PropertyMapping {
    public Expression<Func<object, object>> DomainProperty {get;set;}
    public Expression<Func<object, object>> ViewModelProperty {get;set;}
}

我无法获得上述功能,但I did create something similar以类似的方式工作,但我并不特别喜欢如何设置流畅的界面.我宁愿让它读起来像我上面的方式.

解决方法:

您可以使用以下代码实现它

static class ModelStateMappings
{
    public static DomainModelMapping<TDomainModel> MapDomainModel<TDomainModel>()
    {
        // edit the constructor to pass more information here if needed.
        return new DomainModelMapping<TDomainModel>();
    }
}

public class DomainModelMapping<TDomainModel>
{
    public ViewModelMapping<TDomainModel, TViewModel> MapViewModel<TViewModel>()
    {
        // edit the constructor to pass more information here if needed.
        return new ViewModelMapping<TDomainModel, TViewModel>();
    }
}

public class ViewModelMapping<TDomainModel, TViewModel>
{
    public ViewModelMapping<TDomainModel, TViewModel>
        Properties<TDomainPropertyType, TViewModelPropertyType>(
            Expression<Func<TDomainModel, TDomainPropertyType>> domainExpr,
            Expression<Func<TViewModel, TViewModelPropertyType>> viewModelExpr)
    {
        // map here
        return this;
    }
}

您不必指定所有先前设置的泛型类型,因为它们已被记住为返回类型的泛型参数.可以跳过Properties方法调用的通用参数,因为它们将由编译器推断.而且你得到的打字比在各处使用对象更好.

当然这是最简单的版本.您可以在这些类型之间传递更多信息,因为您指定了下一个必要类型的创建方式.

它还调用MapViewModel而不首先调用MapDomainModel(只要你将构造函数设置为内部并在单独的dll中关闭所有内容),这应该是一件好事.

标签：c,expression,fluent-interface,generics
来源： https://codeday.me/bug/20190517/1120662.html