razor Html.DropdownList provide “Please select” as

问题:

Data:

var countries = new Dictionary<string,string>();
countries.Add("AF","Afghanistan");
countries.Add("US","United States");
countries.Add("FR","France");

Razor:

@Html.DropdownList("Countries",new SelectList(countries, "key", "value", "US"), "Select Country")

Issue: in my razor, I'm specifying "US" for the selectedValue, and "Select Country" for optionLabel. I expect this to insert "Select Country" as the first item in the dropdown, AND have "US" already selected for me.

What actually happens: "Select Country" is inserted, but "US" is NOT selected. "Select Country" is.

Question: can I have both? Where Razor injects "Please Select", but also pre-selects "US" as the default?

Please note: I'm getting the data from a table in my database, so I'd prefer not to have an actual row in there with "Please select", or have to insert it myself into the dictionary. It's easier to do Model.Countries = dbRepo.GetCountries() in my controller vs. declaring an empty dictionary, adding "Please Select", then looping thru .GetCountries() and adding to the original dictionary before setting it to Model.Countries for my view.

Thanks!

回答1:

This should work. No idea why it doesn't because you haven't shown your actual code. Probably there's no option with key = "US" in your actual dataset.

But anyway let me illustrate with an example the approach that I would recommend which is to use a view model and a strongly typed helper DropDownListFor helper.

Model:

public class CountriesViewModel
{
    public string SelectedCountryCode { get; set; }
    public IEnumerable<SelectListItem> Countries { get; set; }
}

Controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var model = new CountriesViewModel();
        // TODO: obviously those will come from your database
        model.Countries = new[]
        {
            new SelectListItem { Value = "AF", Text = "Afghanistan" },
            new SelectListItem { Value = "US", Text = "United States" },
            new SelectListItem { Value = "FR", Text = "France" },
        };

        // Preselect the option with Value = "US"
        // Make sure you have such option in the Countries list
        model.SelectedCountryCode = "US";
        return View(model);
    }
}

View (~/Views/Home/Index.cshtml):

@model CountriesViewModel

@Html.DropDownListFor(
    x => x.SelectedCountryCode,
    Model.Countries, 
    "Select Country"
)

Result:

回答2:

for people looking for a list of countries, this will help

var countries = new[]
                {
                    new SelectListItem { Value = "AF", Text = "AFGHANISTAN"}, 
                    new SelectListItem { Value = "AX", Text = "ÅLAND ISLANDS"}, 
                    new SelectListItem { Value = "AL", Text = "ALBANIA"}, 
                    new SelectListItem { Value = "DZ", Text = "ALGERIA"}, 
                    new SelectListItem { Value = "AS", Text = "AMERICAN SAMOA"}, 
                    new SelectListItem { Value = "AD", Text = "ANDORRA"}, 
                    new SelectListItem { Value = "AO", Text = "ANGOLA"}, 
                    new SelectListItem { Value = "AI", Text = "ANGUILLA"}, 
                    new SelectListItem { Value = "AQ", Text = "ANTARCTICA"}, 
                    new SelectListItem { Value = "AG", Text = "ANTIGUA AND BARBUDA"}, 
                    new SelectListItem { Value = "AR", Text = "ARGENTINA"}, 
                    new SelectListItem { Value = "AM", Text = "ARMENIA"}, 
                    new SelectListItem { Value = "AW", Text = "ARUBA"}, 
                    new SelectListItem { Value = "AU", Text = "AUSTRALIA"}, 
                    new SelectListItem { Value = "AT", Text = "AUSTRIA"}, 
                    new SelectListItem { Value = "AZ", Text = "AZERBAIJAN"}, 
                    new SelectListItem { Value = "BS", Text = "BAHAMAS"}, 
                    new SelectListItem { Value = "BH", Text = "BAHRAIN"}, 
                    new SelectListItem { Value = "BD", Text = "BANGLADESH"}, 
                    new SelectListItem { Value = "BB", Text = "BARBADOS"}, 
                    new SelectListItem { Value = "BY", Text = "BELARUS"}, 
                    new SelectListItem { Value = "BE", Text = "BELGIUM"}, 
                    new SelectListItem { Value = "BZ", Text = "BELIZE"}, 
                    new SelectListItem { Value = "BJ", Text = "BENIN"}, 
                    new SelectListItem { Value = "BM", Text = "BERMUDA"}, 
                    new SelectListItem { Value = "BT", Text = "BHUTAN"}, 
                    new SelectListItem { Value = "BO", Text = "BOLIVIA, PLURINATIONAL STATE OF"}, 
                    new SelectListItem { Value = "BQ", Text = "BONAIRE, SINT EUSTATIUS AND SABA"}, 
                    new SelectListItem { Value = "BA", Text = "BOSNIA AND HERZEGOVINA"}, 
                    new SelectListItem { Value = "BW", Text = "BOTSWANA"}, 
                    new SelectListItem { Value = "BV", Text = "BOUVET ISLAND"}, 
                    new SelectListItem { Value = "BR", Text = "BRAZIL"}, 
                    new SelectListItem { Value = "IO", Text = "BRITISH INDIAN OCEAN TERRITORY"}, 
                    new SelectListItem { Value = "BN", Text = "BRUNEI DARUSSALAM"}, 
                    new SelectListItem { Value = "BG", Text = "BULGARIA"}, 
                    new SelectListItem { Value = "BF", Text = "BURKINA FASO"}, 
                    new SelectListItem { Value = "BI", Text = "BURUNDI"}, 
                    new SelectListItem { Value = "KH", Text = "CAMBODIA"}, 
                    new SelectListItem { Value = "CM", Text = "CAMEROON"}, 
                    new SelectListItem { Value = "CA", Text = "CANADA"}, 
                    new SelectListItem { Value = "CV", Text = "CAPE VERDE"}, 
                    new SelectListItem { Value = "KY", Text = "CAYMAN ISLANDS"}, 
                    new SelectListItem { Value = "CF", Text = "CENTRAL AFRICAN REPUBLIC"}, 
                    new SelectListItem { Value = "TD", Text = "CHAD"}, 
                    new SelectListItem { Value = "CL", Text = "CHILE"}, 
                    new SelectListItem { Value = "CN", Text = "CHINA"}, 
                    new SelectListItem { Value = "CX", Text = "CHRISTMAS ISLAND"}, 
                    new SelectListItem { Value = "CC", Text = "COCOS (KEELING) ISLANDS"}, 
                    new SelectListItem { Value = "CO", Text = "COLOMBIA"}, 
                    new SelectListItem { Value = "KM", Text = "COMOROS"}, 
                    new SelectListItem { Value = "CG", Text = "CONGO"}, 
                    new SelectListItem { Value = "CD", Text = "CONGO, THE DEMOCRATIC REPUBLIC OF THE"}, 
                    new SelectListItem { Value = "CK", Text = "COOK ISLANDS"}, 
                    new SelectListItem { Value = "CR", Text = "COSTA RICA"}, 
                    new SelectListItem { Value = "CI", Text = "CÔTE D'IVOIRE"}, 
                    new SelectListItem { Value = "HR", Text = "CROATIA"}, 
                    new SelectListItem { Value = "CU", Text = "CUBA"}, 
                    new SelectListItem { Value = "CW", Text = "CURAÇAO"}, 
                    new SelectListItem { Value = "CY", Text = "CYPRUS"}, 
                    new SelectListItem { Value = "CZ", Text = "CZECH REPUBLIC"}, 
                    new SelectListItem { Value = "DK", Text = "DENMARK"}, 
                    new SelectListItem { Value = "DJ", Text = "DJIBOUTI"}, 
                    new SelectListItem { Value = "DM", Text = "DOMINICA"}, 
                    new SelectListItem { Value = "DO", Text = "DOMINICAN REPUBLIC"}, 
                    new SelectListItem { Value = "EC", Text = "ECUADOR"}, 
                    new SelectListItem { Value = "EG", Text = "EGYPT"}, 
                    new SelectListItem { Value = "SV", Text = "EL SALVADOR"}, 
                    new SelectListItem { Value = "GQ", Text = "EQUATORIAL GUINEA"}, 
                    new SelectListItem { Value = "ER", Text = "ERITREA"}, 
                    new SelectListItem { Value = "EE", Text = "ESTONIA"}, 
                    new SelectListItem { Value = "ET", Text = "ETHIOPIA"}, 
                    new SelectListItem { Value = "FK", Text = "FALKLAND ISLANDS (MALVINAS)"}, 
                    new SelectListItem { Value = "FO", Text = "FAROE ISLANDS"}, 
                    new SelectListItem { Value = "FJ", Text = "FIJI"}, 
                    new SelectListItem { Value = "FI", Text = "FINLAND"}, 
                    new SelectListItem { Value = "FR", Text = "FRANCE"}, 
                    new SelectListItem { Value = "GF", Text = "FRENCH GUIANA"}, 
                    new SelectListItem { Value = "PF", Text = "FRENCH POLYNESIA"}, 
                    new SelectListItem { Value = "TF", Text = "FRENCH SOUTHERN TERRITORIES"}, 
                    new SelectListItem { Value = "GA", Text = "GABON"}, 
                    new SelectListItem { Value = "GM", Text = "GAMBIA"}, 
                    new SelectListItem { Value = "GE", Text = "GEORGIA"}, 
                    new SelectListItem { Value = "DE", Text = "GERMANY"}, 
                    new SelectListItem { Value = "GH", Text = "GHANA"}, 
                    new SelectListItem { Value = "GI", Text = "GIBRALTAR"}, 
                    new SelectListItem { Value = "GR", Text = "GREECE"}, 
                    new SelectListItem { Value = "GL", Text = "GREENLAND"}, 
                    new SelectListItem { Value = "GD", Text = "GRENADA"}, 
                    new SelectListItem { Value = "GP", Text = "GUADELOUPE"}, 
                    new SelectListItem { Value = "GU", Text = "GUAM"}, 
                    new SelectListItem { Value = "GT", Text = "GUATEMALA"}, 
                    new SelectListItem { Value = "GG", Text = "GUERNSEY"}, 
                    new SelectListItem { Value = "GN", Text = "GUINEA"}, 
                    new SelectListItem { Value = "GW", Text = "GUINEA-BISSAU"}, 
                    new SelectListItem { Value = "GY", Text = "GUYANA"}, 
                    new SelectListItem { Value = "HT", Text = "HAITI"}, 
                    new SelectListItem { Value = "HM", Text = "HEARD ISLAND AND MCDONALD ISLANDS"}, 
                    new SelectListItem { Value = "VA", Text = "HOLY SEE (VATICAN CITY STATE)"}, 
                    new SelectListItem { Value = "HN", Text = "HONDURAS"}, 
                    new SelectListItem { Value = "HK", Text = "HONG KONG"}, 
                    new SelectListItem { Value = "HU", Text = "HUNGARY"}, 
                    new SelectListItem { Value = "IS", Text = "ICELAND"}, 
                    new SelectListItem { Value = "IN", Text = "INDIA"}, 
                    new SelectListItem { Value = "ID", Text = "INDONESIA"}, 
                    new SelectListItem { Value = "IR", Text = "IRAN, ISLAMIC REPUBLIC OF"}, 
                    new SelectListItem { Value = "IQ", Text = "IRAQ"}, 
                    new SelectListItem { Value = "IE", Text = "IRELAND"}, 
                    new SelectListItem { Value = "IM", Text = "ISLE OF MAN"}, 
                    new SelectListItem { Value = "IL", Text = "ISRAEL"}, 
                    new SelectListItem { Value = "IT", Text = "ITALY"}, 
                    new SelectListItem { Value = "JM", Text = "JAMAICA"}, 
                    new SelectListItem { Value = "JP", Text = "JAPAN"}, 
                    new SelectListItem { Value = "JE", Text = "JERSEY"}, 
                    new SelectListItem { Value = "JO", Text = "JORDAN"}, 
                    new SelectListItem { Value = "KZ", Text = "KAZAKHSTAN"}, 
                    new SelectListItem { Value = "KE", Text = "KENYA"}, 
                    new SelectListItem { Value = "KI", Text = "KIRIBATI"}, 
                    new SelectListItem { Value = "KP", Text = "KOREA, DEMOCRATIC PEOPLE'S REPUBLIC OF"}, 
                    new SelectListItem { Value = "KR", Text = "KOREA, REPUBLIC OF"}, 
                    new SelectListItem { Value = "KW", Text = "KUWAIT"}, 
                    new SelectListItem { Value = "KG", Text = "KYRGYZSTAN"}, 
                    new SelectListItem { Value = "LA", Text = "LAO PEOPLE'S DEMOCRATIC REPUBLIC"}, 
                    new SelectListItem { Value = "LV", Text = "LATVIA"}, 
                    new SelectListItem { Value = "LB", Text = "LEBANON"}, 
                    new SelectListItem { Value = "LS", Text = "LESOTHO"}, 
                    new SelectListItem { Value = "LR", Text = "LIBERIA"}, 
                    new SelectListItem { Value = "LY", Text = "LIBYA"}, 
                    new SelectListItem { Value = "LI", Text = "LIECHTENSTEIN"}, 
                    new SelectListItem { Value = "LT", Text = "LITHUANIA"}, 
                    new SelectListItem { Value = "LU", Text = "LUXEMBOURG"}, 
                    new SelectListItem { Value = "MO", Text = "MACAO"}, 
                    new SelectListItem { Value = "MK", Text = "MACEDONIA, THE FORMER YUGOSLAV REPUBLIC OF"}, 
                    new SelectListItem { Value = "MG", Text = "MADAGASCAR"}, 
                    new SelectListItem { Value = "MW", Text = "MALAWI"}, 
                    new SelectListItem { Value = "MY", Text = "MALAYSIA"}, 
                    new SelectListItem { Value = "MV", Text = "MALDIVES"}, 
                    new SelectListItem { Value = "ML", Text = "MALI"}, 
                    new SelectListItem { Value = "MT", Text = "MALTA"}, 
                    new SelectListItem { Value = "MH", Text = "MARSHALL ISLANDS"}, 
                    new SelectListItem { Value = "MQ", Text = "MARTINIQUE"}, 
                    new SelectListItem { Value = "MR", Text = "MAURITANIA"}, 
                    new SelectListItem { Value = "MU", Text = "MAURITIUS"}, 
                    new SelectListItem { Value = "YT", Text = "MAYOTTE"}, 
                    new SelectListItem { Value = "MX", Text = "MEXICO"}, 
                    new SelectListItem { Value = "FM", Text = "MICRONESIA, FEDERATED STATES OF"}, 
                    new SelectListItem { Value = "MD", Text = "MOLDOVA, REPUBLIC OF"}, 
                    new SelectListItem { Value = "MC", Text = "MONACO"}, 
                    new SelectListItem { Value = "MN", Text = "MONGOLIA"}, 
                    new SelectListItem { Value = "ME", Text = "MONTENEGRO"}, 
                    new SelectListItem { Value = "MS", Text = "MONTSERRAT"}, 
                    new SelectListItem { Value = "MA", Text = "MOROCCO"}, 
                    new SelectListItem { Value = "MZ", Text = "MOZAMBIQUE"}, 
                    new SelectListItem { Value = "MM", Text = "MYANMAR"}, 
                    new SelectListItem { Value = "NA", Text = "NAMIBIA"}, 
                    new SelectListItem { Value = "NR", Text = "NAURU"}, 
                    new SelectListItem { Value = "NP", Text = "NEPAL"}, 
                    new SelectListItem { Value = "NL", Text = "NETHERLANDS"}, 
                    new SelectListItem { Value = "NC", Text = "NEW CALEDONIA"}, 
                    new SelectListItem { Value = "NZ", Text = "NEW ZEALAND"}, 
                    new SelectListItem { Value = "NI", Text = "NICARAGUA"}, 
                    new SelectListItem { Value = "NE", Text = "NIGER"}, 
                    new SelectListItem { Value = "NG", Text = "NIGERIA"}, 
                    new SelectListItem { Value = "NU", Text = "NIUE"}, 
                    new SelectListItem { Value = "NF", Text = "NORFOLK ISLAND"}, 
                    new SelectListItem { Value = "MP", Text = "NORTHERN MARIANA ISLANDS"}, 
                    new SelectListItem { Value = "NO", Text = "NORWAY"}, 
                    new SelectListItem { Value = "OM", Text = "OMAN"}, 
                    new SelectListItem { Value = "PK", Text = "PAKISTAN"}, 
                    new SelectListItem { Value = "PW", Text = "PALAU"}, 
                    new SelectListItem { Value = "PS", Text = "PALESTINIAN TERRITORY, OCCUPIED"}, 
                    new SelectListItem { Value = "PA", Text = "PANAMA"}, 
                    new SelectListItem { Value = "PG", Text = "PAPUA NEW GUINEA"}, 
                    new SelectListItem { Value = "PY", Text = "PARAGUAY"}, 
                    new SelectListItem { Value = "PE", Text = "PERU"}, 
                    new SelectListItem { Value = "PH", Text = "PHILIPPINES"}, 
                    new SelectListItem { Value = "PN", Text = "PITCAIRN"}, 
                    new SelectListItem { Value = "PL", Text = "POLAND"}, 
                    new SelectListItem { Value = "PT", Text = "PORTUGAL"}, 
                    new SelectListItem { Value = "PR", Text = "PUERTO RICO"}, 
                    new SelectListItem { Value = "QA", Text = "QATAR"}, 
                    new SelectListItem { Value = "RE", Text = "RÉUNION"}, 
                    new SelectListItem { Value = "RO", Text = "ROMANIA"}, 
                    new SelectListItem { Value = "RU", Text = "RUSSIAN FEDERATION"}, 
                    new SelectListItem { Value = "RW", Text = "RWANDA"}, 
                    new SelectListItem { Value = "BL", Text = "SAINT BARTHÉLEMY"}, 
                    new SelectListItem { Value = "SH", Text = "SAINT HELENA, ASCENSION AND TRISTAN DA CUNHA"}, 
                    new SelectListItem { Value = "KN", Text = "SAINT KITTS AND NEVIS"}, 
                    new SelectListItem { Value = "LC", Text = "SAINT LUCIA"}, 
                    new SelectListItem { Value = "MF", Text = "SAINT MARTIN (FRENCH PART)"}, 
                    new SelectListItem { Value = "PM", Text = "SAINT PIERRE AND MIQUELON"}, 
                    new SelectListItem { Value = "VC", Text = "SAINT VINCENT AND THE GRENADINES"}, 
                    new SelectListItem { Value = "WS", Text = "SAMOA"}, 
                    new SelectListItem { Value = "SM", Text = "SAN MARINO"}, 
                    new SelectListItem { Value = "ST", Text = "SAO TOME AND PRINCIPE"}, 
                    new SelectListItem { Value = "SA", Text = "SAUDI ARABIA"}, 
                    new SelectListItem { Value = "SN", Text = "SENEGAL"}, 
                    new SelectListItem { Value = "RS", Text = "SERBIA"}, 
                    new SelectListItem { Value = "SC", Text = "SEYCHELLES"}, 
                    new SelectListItem { Value = "SL", Text = "SIERRA LEONE"}, 
                    new SelectListItem { Value = "SG", Text = "SINGAPORE"}, 
                    new SelectListItem { Value = "SX", Text = "SINT MAARTEN (DUTCH PART)"}, 
                    new SelectListItem { Value = "SK", Text = "SLOVAKIA"}, 
                    new SelectListItem { Value = "SI", Text = "SLOVENIA"}, 
                    new SelectListItem { Value = "SB", Text = "SOLOMON ISLANDS"}, 
                    new SelectListItem { Value = "SO", Text = "SOMALIA"}, 
                    new SelectListItem { Value = "ZA", Text = "SOUTH AFRICA"}, 
                    new SelectListItem { Value = "GS", Text = "SOUTH GEORGIA AND THE SOUTH SANDWICH ISLANDS"}, 
                    new SelectListItem { Value = "SS", Text = "SOUTH SUDAN"}, 
                    new SelectListItem { Value = "ES", Text = "SPAIN"}, 
                    new SelectListItem { Value = "LK", Text = "SRI LANKA"}, 
                    new SelectListItem { Value = "SD", Text = "SUDAN"}, 
                    new SelectListItem { Value = "SR", Text = "SURINAME"}, 
                    new SelectListItem { Value = "SJ", Text = "SVALBARD AND JAN MAYEN"}, 
                    new SelectListItem { Value = "SZ", Text = "SWAZILAND"}, 
                    new SelectListItem { Value = "SE", Text = "SWEDEN"}, 
                    new SelectListItem { Value = "CH", Text = "SWITZERLAND"}, 
                    new SelectListItem { Value = "SY", Text = "SYRIAN ARAB REPUBLIC"}, 
                    new SelectListItem { Value = "TW", Text = "TAIWAN, PROVINCE OF CHINA"}, 
                    new SelectListItem { Value = "TJ", Text = "TAJIKISTAN"}, 
                    new SelectListItem { Value = "TZ", Text = "TANZANIA, UNITED REPUBLIC OF"}, 
                    new SelectListItem { Value = "TH", Text = "THAILAND"}, 
                    new SelectListItem { Value = "TL", Text = "TIMOR-LESTE"}, 
                    new SelectListItem { Value = "TG", Text = "TOGO"}, 
                    new SelectListItem { Value = "TK", Text = "TOKELAU"}, 
                    new SelectListItem { Value = "TO", Text = "TONGA"}, 
                    new SelectListItem { Value = "TT", Text = "TRINIDAD AND TOBAGO"}, 
                    new SelectListItem { Value = "TN", Text = "TUNISIA"}, 
                    new SelectListItem { Value = "TR", Text = "TURKEY"}, 
                    new SelectListItem { Value = "TM", Text = "TURKMENISTAN"}, 
                    new SelectListItem { Value = "TC", Text = "TURKS AND CAICOS ISLANDS"}, 
                    new SelectListItem { Value = "TV", Text = "TUVALU"}, 
                    new SelectListItem { Value = "UG", Text = "UGANDA"}, 
                    new SelectListItem { Value = "UA", Text = "UKRAINE"}, 
                    new SelectListItem { Value = "AE", Text = "UNITED ARAB EMIRATES"}, 
                    new SelectListItem { Value = "GB", Text = "UNITED KINGDOM"}, 
                    new SelectListItem { Value = "US", Text = "UNITED STATES"}, 
                    new SelectListItem { Value = "UM", Text = "UNITED STATES MINOR OUTLYING ISLANDS"}, 
                    new SelectListItem { Value = "UY", Text = "URUGUAY"}, 
                    new SelectListItem { Value = "UZ", Text = "UZBEKISTAN"}, 
                    new SelectListItem { Value = "VU", Text = "VANUATU"}, 
                    new SelectListItem { Value = "VE", Text = "VENEZUELA, BOLIVARIAN REPUBLIC OF"}, 
                    new SelectListItem { Value = "VN", Text = "VIET NAM"}, 
                    new SelectListItem { Value = "VG", Text = "VIRGIN ISLANDS, BRITISH"}, 
                    new SelectListItem { Value = "VI", Text = "VIRGIN ISLANDS, U.S."}, 
                    new SelectListItem { Value = "WF", Text = "WALLIS AND FUTUNA"}, 
                    new SelectListItem { Value = "EH", Text = "WESTERN SAHARA"}, 
                    new SelectListItem { Value = "YE", Text = "YEMEN"}, 
                    new SelectListItem { Value = "ZM", Text = "ZAMBIA"}, 
                    new SelectListItem { Value = "ZW", Text = "ZIMBABWE"}, 

                };

回答3:

I know this post is old, but for people looking for list of coutries this is the easy way :

// List of coutries
List<string> CountryList = new List<string>();

CultureInfo[] CInfoList = CultureInfo.GetCultures(CultureTypes.SpecificCultures);

CountryList.Add("");
foreach (CultureInfo CInfo in CInfoList)
{
    RegionInfo R = new RegionInfo(CInfo.LCID);
    if (!(CountryList.Contains(R.EnglishName)))
    {
        CountryList.Add(R.EnglishName);
    }
}
CountryList.Sort();

回答4:

The answer here: ASP.Net Html.DropDownList Selected Element not Selected could also be the solution.

You use "Countries" for the name of the dropdown and "countries" as the name of the SelectList. Try renaming one or the other to something different.