如何编写通用的IEnumerable <SelectListItem>扩展方法

Question

对于仿制药我是新的(好的,真的很新),但我喜欢它们的想法.我将在视图上有一些下拉列表,我想要一个通用的方法来获取对象列表并将其转换为列表SelectListItems

我现在拥有的:

public static IEnumerable<SelectListItem> ToSelectListItems(
     this IEnumerable<SpecificObject> items, long selectedId)
    {
        return
            items.OrderBy(item => item.Name)
            .Select(item =>
                    new SelectListItem
                    {
                        Selected = (item.Id == selectedId),
                        Text = item.Name,
                        Value = item.Id.ToString()
                    });
    }

麻烦的是,我需要为每个下拉列表重复该代码,因为对象具有代表该Text属性的不同字段SelectListItem

这是我想要完成的事情:

public static IEnumerable<SelectListItem> ToSelectListItem<T>(this IEnumerable<T> items, string key, string value, int SelectedId) {
    // I really have no idea how to proceed from here :(
}

Answer 1

好吧,你可以这样做:

public static IEnumerable<SelectListItem> ToSelectListItems(
     this IEnumerable<T> items, 
     Func<T,string> nameSelector, 
     Func<T,string> valueSelector, 
     Func<T,bool> selected)
{
     return items.OrderBy(item => nameSelector(item))
            .Select(item =>
                    new SelectListItem
                    {
                        Selected = selected(item),
                        Text = nameSelector(item),
                        Value = valueSelector(item)
                    });
}

Answer 2

您可以传入代理进行比较和属性检索.像这样的东西:

public static IEnumerable<SelectListItem> ToSelectListItem<T>(this IEnumerable<T> items, 
    int selectedId, Func<T,int> getId, Func<T, string> getName, 
    Func<T, string> getText, Func<T, string> getValue)
{
    return
        items.OrderBy(item => getName(item))
        .Select(item =>
                new SelectListItem
                {
                    Selected = (getId(item) == selectedId),
                    Text = getText(item),
                    Value = getValue(item)
                });
}

然后你会像这样使用它:

var selected = specificObjects.ToSelectListItem(10, s => s.Id, s=> s.Name, s => s.Name, s => s.Id.ToString());