ASP.NET Core Razor页面-不在POST请求上绑定

Question

I have the following on my Login.cshtml.cs code file:

Login.cshtml.cs

public class LoginModel : PageModel
{
    public string ReturnUrl { get; set; }
    public bool EnableLocalLogin { get; set; } = true;
    public string Username { get; set; }
    public string Password { get; set; }

    private readonly IIdentityServerInteractionService _interaction;

    public LoginModel(IIdentityServerInteractionService interaction)
    {
        _interaction = interaction;
    }

    public IActionResult OnGet(string returnUrl)
    {            
        ReturnUrl = returnUrl;
        return Page();
    }

    public IActionResult OnPost([FromBody]LoginModel model, string button)
    {
        // todo - implement
        return Page();
    }
}

If I have a breakpoint on the return line of OnPost and I hit the Login button from the page - the breakpoint is hit - however the model is null. From Dev Tools however it seems the values from the model are being sent as form data. So I changed the [FromBody] to [FromForm] .

However when I run this code and hit the Login button I get the following exception:

InvalidOperationException: Could not create an instance of type 'CarWarehouse.LoginModel'. Model bound complex types must not be abstract or value types and must have a parameterless constructor.

UPDATE

The Login.cshtml page:

@page
@model MyProj.Pages.LoginModel
@{
    ViewData["Title"] = "Consent Required";
    Layout = "_Layout";
}
@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

@if (Model.EnableLocalLogin)
{
    <div class="col-sm-6">
        <div class="panel panel-default">
            <div class="panel-heading">
                <h3 class="panel-title">Local Login</h3>
            </div>
            <div class="panel-body">

                <form asp-route="Login">
                    <input type="hidden" asp-for="ReturnUrl" />

                    <fieldset>
                        <div class="form-group">
                            <label asp-for="Username"></label>
                            <input class="form-control" placeholder="Username" asp-for="Username" autofocus>
                        </div>
                        <div class="form-group">
                            <label asp-for="Password"></label>
                            <input type="password" class="form-control" placeholder="Password" asp-for="Password" autocomplete="off">
                        </div>

                        <div class="form-group">
                            <button class="btn btn-primary" name="button" value="login">Login</button>
                            <button class="btn btn-default" name="button" value="cancel">Cancel</button>
                        </div>
                    </fieldset>
                </form>
            </div>
        </div>
    </div>
}

Note I am using ID Server 4 and just trying too implement similar logic to this repo - https://github.com/IdentityServer/IdentityServer4.Quickstart.UI/tree/master

Answer 1

Reference Model Binding in ASP.NET Core: [BindProperties] attribute

Available in ASP.NET Core 2.1 and later. Can be applied to a controller or PageModel class to tell model binding to target all public properties of the class:

[BindProperties(SupportsGet=true)]
public class LoginModel : PageModel {
    public string ReturnUrl { get; set; }
    public bool EnableLocalLogin { get; set; } = true;
    public string Username { get; set; }
    public string Password { get; set; }

    private readonly IIdentityServerInteractionService _interaction;

    public LoginModel(IIdentityServerInteractionService interaction) {
        _interaction = interaction;
    }

    public IActionResult OnGet(string returnUrl) { 
        ReturnUrl = returnUrl;
        return Page();
    }

    public IActionResult OnPost(string button) {
        //access properties here which should be populated from form.

        // todo - implement
        return Page();
    }
}