using select options to get value in asp.net razor page - asp.net-core

Question

I want to create a select option to input one of a few fixed values and have it return a matching value to a variable similar to how the input text fields, how would I do this? This was my attempt, the <input type="text"> works fine but the select types return null.
<div class="text-center">
<h1 class="display-4">Add new patient</h1>
<form method="post">
<input type="text" asp-for="patientModel.PatientID" placeholder="Patient ID" />
<input type="text" asp-for="patientModel.FirstName" placeholder="First Name" />
<input type="text" asp-for="patientModel.SecondName" placeholder="Second Name" />
<input type="text" asp-for="patientModel.Location" placeholder="Location" />
<select id="active" name="active" asp-for="patientModel.Sex">
<option value="ACTIVE">MALE</option>
<option value="INACTIVE">FEMALE</option>
<option value="OTHER">OTHER</option>
</select>
<select id="active" name="active" asp-for="patientModel.Active">
<option value="ACTIVE">ACTIVE</option>
<option value="INACTIVE">INACTIVE</option>
</select>
<button type="submit">Submit</button>
</form>
</div>
public class addnewpatientModel : PageModel
{
[BindProperty]
public PatientModel patientModel { get; set; }
public void OnGet()
{
}
public IActionResult OnPost()
{
return RedirectToPage("/index");
}
}

Answer 1

Change the name attribute for the select tag or just remove it:
<select id="sex" name="patientModel.Sex" asp-for="patientModel.Sex">
<select id="active" name="patientModel.Active" asp-for="patientModel.Active">

Answer 2

Try this link. I think you'll find an answer here
The select element has a name attribute. This is used as the key for any selected value(s) when a form is submitted. You can access the value by passing the key as an indexer to the Request.
var value = Request.Form["active"];
The recommended approach, however is to add a suitable property to the PageModel and to allow model binding to apply the posted value to the property:
public class addnewpatientModel : PageModel
{
[BindProperty]
public int active { get; set; }
public void OnPost()
{
// posted value is assigned to the Number property automatically
}
}