在ASP.NET Core 2.1中设置选定的选项

Question

I am developing a web application using C# with asp.net core 2.1.

What I want to achieve is to set the selected option dynamically based on a condition and output the value of (isSelected) variable, here is my code

<select asp-for="SelectedLocation" class="form-control">
    @foreach (var location in Model.Locations)
    {
        var isSelected = location.Number == Model.SelectedLocation ? "selected" : "";
        <option value="@location.Number" data-latitude="@Location.Latitude" data-longitude="@location.Longitude">@location.Title</option>
    }
</select>

Answer 1

Use a ternary operator

@(location.isSelected? "selected" : "")

Your code would look like the following:

<select asp-for="SelectedLocation" class="form-control">
    @foreach (var location in Model.Locations)
    {
        var isSelected = location.Number == Model.SelectedLocation ? "selected" : "";
        <option value="@location.Number" data-latitude="@Location.Latitude" data-longitude="@location.Longitude" @(location.isSelected? "selected" : "")>@location.Title</option>
    }
</select>

What it does is: if isSelected is true it'll add a selected attribute otherwise it'll add nothing.

You can also break it up and write is as a normal if statement, however I hate razor formatting in VS so I avoid razor as much as I can hence the ternary suggestion.