SelectList多年

Question

This is probably really simple... I am trying to create a SelectList containing years from the current one, back until 2008. This will always be the case. For example, in the year 2020, my SelectList will contain values from 2020 - 2008.

I set up this loop, but I'm not sure what the best place to go with this is

for (int i = currentYear; i != 2009; --i)
{

}

Is it possible to create a single SelectListItem and "add" it to a SelectList for each iteration?

I don't think my statement above is possible, so my next thought was to create a list of years, then use LINQ to create it.

var selectList = ListOfYears.Select(new SelectListItem
{
    Value =
    Text = 
});

But then I'm not entirely sure how to get the value from the list. Thanks

Answer 1

var selectList = 
    new SelectList(Enumerable.Range(2008, (DateTime.Now.Year - 2008) + 1));

Answer 2

I had to change the accepted answer slightly to work in older browsers. I ended up with a select list missing the values like this

<option value="">1996</option><option value="">1997</option>

I had to alter the code above to this

var yr = Enumerable.Range(1996, (DateTime.Now.Year - 1995)).Reverse().Select(x => new SelectListItem { Value = x.ToString(), Text = x.ToString() });
        return new SelectList(yr.ToList(), "Value", "Text");

Answer 3

Rather than add a SelectListItem to a SelectList , simply add it to a List<SelectListItem> . Razor can use a List<SelectListItem> as a source.

Answer 4

I created a function to help me out with this. It will reverse it automatically depending on the values you give it.

Check it out, let me know what you think and if you can improve upon it:

public static IEnumerable<SelectListItem> Years(int from, int to, int? value = default(int?)) {
    var reverse = from > to;
    var min = reverse ? to : from;
    var max = reverse ? from : to;

    var years = Enumerable.Range(min, max - min);

    if (reverse) {
        years = years.Reverse();
    }

    return years.Select(year => new SelectListItem {
        Value = year.ToString(),
        Text = year.ToString(),
        Selected = value.Equals(year),
    });
}

Use:

Years(DateTime.Now.Year, DateTime.Now.Year + 4)
/* result: (currently 2018)
   2018
   2019
   2020
   2021
*/

Years(DateTime.Now.Year + 4, DateTime.Now.Year, 2019)
/* result: (currently 2018)
   2021
   2020
   2019 (selected)
   2018
*/