角色是null at Post request for ASP.NET Core Razor Pages

Question

I have this Razor Pages which show a textbox and a button. Upon clicked, it will create/insert a Role into the table. Problem is when I put a breakpoint at the OnPostAsync method, role parameter is null.

This is my front-end code:

@page
@model CreateModel

@{
    ViewData["Title"] = "Create";
}
<h1>Create Role</h1>
<hr />
<div class="row">
    <div class="col-md-4">
            <form asp-route-returnUrl="@Model.ReturnUrl" method="post">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <div class="form-group">
                    <label asp-for="Input.Name"></label>
                    <input asp-for="Input.Name" class="form-control" />
                    <span asp-validation-for="Input.Name" class="text-danger"></span>
                </div>
                <div class="form-group">
                    <input type="submit" value="Create" class="btn btn-primary" />
                </div>
            </form>
</div>
</div>

This is my code-behind:

public class CreateModel : PageModel
{
    private readonly RoleManager<IdentityRole> _roleManager;

    public CreateModel(RoleManager<IdentityRole> roleManager)
    {
        _roleManager = roleManager;
    }

    [BindProperty]
    public IdentityRole Name { get; set; }

    public InputModel Input { get; set; }

    public string ReturnUrl { get; set; }

    public class InputModel
    {
        [Required]
        [StringLength(100, ErrorMessage = "The {0} must be at least {2} and at max {1} characters long.", MinimumLength = 3)]
        [Display(Name = "Role Name")]

        public IdentityRole Name { get; set; }
        //public string Name { get; set; }
    }

    public void OnGet(string returnUrl = null)
    {
        ReturnUrl = returnUrl;
    }

    public async Task<IActionResult> OnPostAsync(IdentityRole role) {
        await _roleManager.CreateAsync(role);
        return Page();
    }
}

Answer 1

The problem may come from the returned type of IdentityRole , in the client, your browser doesn't know how to convert a variable type to IdentityRole . Some popular types are: string , int , List<T> ...

So, in this case, I suggest to use a string instead.

public InputModel Input { get; set; }

public class InputModel
{
    public string Name { get; set; }
}


public async Task<IActionResult> OnPostAsync() {
    await _roleManager.CreateAsync(new IdentityRole { Name = Input.Name });
    return Page();
}