How Does the ASP.NET Core MVC Select Tag Helper Work for Dynamic Dropdown Lists?

In ASP.NET core MVC, use Select Tag Helper to create a dynamic drop -down list

SELECT TAG Helper provides a flexible way to render HTML

elements in the Razor view. It supports data binding with the view model attribute, allowing you to dynamically fill the option and set the selected items.

<select> Use Select Tag Helper

SELECT tag Helper has the following attributes:

: The attributes that bind the elements into the view model.
• asp-for : Specify the option list to be displayed in the <select> element.
• asp-items: Other HTML attributes of the elements, such as <select>,
,
• , etc. asp-(其他属性) Binded to the option list <select> class id Bind element to the option list, please use the multiple attribute. This value can be a collection of string, integer or custom objects.

For example, the

element must be bound to the name of the employee's surname:

Set selection options

<select> asp-items To set the initial selected option, just set the value of the corresponding attribute in the view model.

<select> In the controller:

<code class="language-html"><select asp-for="EmployeeId" asp-items="@Model.EmployeesList"></select></code>

additional function

SELECT TAG Helper provides other functions, such as:

<code class="language-csharp">public class MyViewModel
{
    public int EmployeeId { get; set; }
    public List<Employee> EmployeesList { get; set; }
}

public class Employee
{
    public int Id { get; set; }
    public string FullName { get; set; }
}</code>

Multi -choice

: By setting the

attribute, you can create a multi -choice drop -down menu.

<code class="language-csharp">public IActionResult Create()
{
    var vm = new MyViewModel();
    vm.EmployeesList = new List<Employee>
    {
        new Employee { Id = 1, FullName = "Shyju" },
        new Employee { Id = 2, FullName = "Bryan" }
    };
    vm.EmployeeId = 2; // 设置初始选定的员工
    return View(vm);
}</code>

Group : You can use the attributes of each

object to group the options.

Custom values ​​and display attributes

: By speculating
• and attributes, you can customize the value of the option and display text. multiple Verification
: SELECT TAG Helper supports the use of
• attributes for non -invasive verification. SelectListItem By using these functions, you can create a rich and dynamic drop -down list in the ASP.NET core MVC application. asp-group

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