我尝试从DB表中获取模型，对其进行更改，然后在回发表单时更新所做的更改。我一直在挖掘通过多种资源试图找到这个问题的解决方案，似乎不能理解到底是怎么回事，或找到一个很好的解决方案。
从以前的讲座和经验，我已经得到了这个工作使用

_context.Attach(Model).state = EntityState.Modified;

它会工作得很好。现在，在另一个页面上，试图实现相同的技术，我运行到以下错误。

错误信息

InvalidOperationException: The property 'SpeakerForm.SpeakerFormId' has a temporary value while attempting to change the entity's state to 'Modified'. Either set a permanent value explicitly, or ensure that the database is configured to generate values for this property.
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetEntityState(EntityState oldState, EntityState newState, bool acceptChanges, bool modifyProperties)
Microsoft.EntityFrameworkCore.ChangeTracking.Internal.InternalEntityEntry.SetEntityState(EntityState entityState, bool acceptChanges, bool modifyProperties, Nullable<EntityState> forceStateWhenUnknownKey, Nullable<EntityState> fallbackState)
Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry.set_State(EntityState value)
LosBarriosEvents.Pages.SpeakerFormsEditModel.OnPostAsync() in Edit.cshtml.cs
+
        _context.SpeakerForms.Attach(Form).State = EntityState.Modified;

型号

这是我的“SpeakerForm”模型，这是我尝试编辑的主要模型：

using System.ComponentModel.DataAnnotations;

namespace LosBarriosEvents.Models;

public class SpeakerForm
{
    [Key]
    public int SpeakerFormId { get; set; }

    public string Title { get; set; } = string.Empty;
    public string Description { get; set; } = string.Empty;
    public string Duration { get; set; } = string.Empty;

    //Navigation Properties
    public string SpeakerId { get; set; }
    public Speaker? Speaker { get; set; }
}

与“Speaker”绑定为FK：

using System.ComponentModel.DataAnnotations;

namespace LosBarriosEvents.Models
{
    public class Speaker
    {
        [Key]
        public string SpeakerId { get; set; } = default!;//PK

        public string firstName { get; set; } = string.Empty;
        public string lastName { get; set; } = string.Empty;
        public string email { get; set; } = string.Empty;
        public string phoneNumber { get; set; } = string.Empty;

        //Navigation Properties
        public List<SpeakerForm>? SpeakerForms { get; set; }
    }
}

编辑.cshtml.cs

然后，我在代码隐藏页面上使用这些代码来尝试绑定属性，在前端进行更改，然后进行更新

using System.Security.Claims;
using LosBarriosEvents.Areas.Identity.Data;
using LosBarriosEvents.Authorization;
using LosBarriosEvents.Data;
using LosBarriosEvents.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.EntityFrameworkCore;

namespace LosBarriosEvents.Pages;

[Authorize(Roles = "Administrators,Speakers")]

public class SpeakerFormsEditModel : PageModel
{

    private readonly ILogger<SpeakerFormsEditModel> _logger;
    private readonly ApplicationDbContext _context;
    private readonly UserManager<LosBarriosUser> _userManager;

    public SpeakerFormsEditModel(ILogger<SpeakerFormsEditModel> logger, ApplicationDbContext context, UserManager<LosBarriosUser> userManager)
    {
        _logger = logger;
        _context = context;
        _userManager = userManager;
    }

    [BindProperty]
    public SpeakerForm Form { get; set; }

    public IActionResult OnGet(int? id)
    {
        var userId = _userManager.GetUserId(User);

        SpeakerForm frm = _context.SpeakerForms.FirstOrDefault(f => f.SpeakerFormId == id);

        if (frm == null)
        {
            return NotFound();
        }

        Form = frm;

        return Page();
    }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        var isAuthorized = User.IsInRole(UserRoles.LosBarriosEventsSpeakerRole) || User.IsInRole(UserRoles.LosBarriosEventsAdministratorRole);

        if (!isAuthorized)
        {
            return Forbid();
        }

        _context.SpeakerForms.Attach(Form).State = EntityState.Modified;

        await _context.SaveChangesAsync();

        return RedirectToPage("./Index");
    }
}

edit.cshtml

绑定到Razorpage并在发布时回调

@page
@model SpeakerFormsEditModel
@{
    ViewData["Title"] = "Home page";
}

<div class="text-center">
    <h1 class="display-4">Edit Speaker Form</h1>
</div>

<form id="SpeakerEditForm" method="post">
    <h2>Edit Form</h2>
    <hr />
    <div asp-validation-summary="ModelOnly" class="text-danger" role="alert"></div>

    <div class="form-floating mb-3">
        <input asp-for="Form.Title" class="form-control" aria-required="true" placeholder="Lecture Title" />
        <label asp-for="Form.Title">Lecture Title</label>
        <span asp-validation-for="Form.Title" class="text-danger"></span>
    </div>
    <div class="form-floating mb-3">
        <input asp-for="Form.Description" class="form-control" aria-required="true" placeholder="Description" />
        <label asp-for="Form.Description">Description of Lecture</label>
        <span asp-validation-for="Form.Description" class="text-danger"></span>
    </div>
    <div class="form-floating mb-3">
        <input asp-for="Form.Duration" class="form-control" aria-required="true" placeholder="Lecture Duration" />
        <label asp-for="Form.Duration">Duration</label>
        <span asp-validation-for="Form.Duration" class="text-danger"></span>
    </div>
    <div class="form-floating mb-3">
        <input asp-for="Form.SpeakerId" type="hidden"/>
    </div>
    <div class="form-floating mb-3">
        <input asp-for="Form.Speaker" type="hidden"/>
    </div>

    <button id="SpeakerFormSubmit" type="submit" class="w-100 btn btn-lg btn-primary">Submit</button>
</form>
<a asp-page="./Index">Back to Forms</a>

我尝试了几乎所有我能找到的stackoverflow，microsoft和github帖子的变体，发现自己试图向墙上扔东西，直到它粘上几个小时。没有运气，我决定最终尝试并在这里发布。对我来说奇怪的是，我在另一个模型的另一个编辑页面上几乎完全复制了这段代码，并且能够很好地工作。我觉得这是如此微不足道的事情，但我一直在疯狂地试图弄清楚这一点。我还通过迁移来验证它是正确构建的，据我所知没有发现任何错误。任何帮助和提前谢谢你