C# 更新验证失败后，使用.Include（相关实体）重新显示原始模型

当用户发送GET请求以编辑记录时，我正在加载通过相关实体发送到视图的模型。包括如下内容：

 var client = await _context.Client
                             .Include(c => c.Office)
                             .Where(c => c.client_id == id)
                             .AsNoTracking()
                             .SingleOrDefaultAsync();
 return View(client);

当用户发回编辑表单和必填字段缺少ModelState.IsValid==false时，将不执行更新，并将包含未保存更改的模型发送回视图

public async Task<IActionResult> Edit(Client client_edited )
{
    if (!ModelState.IsValid)
    {
            return View(client_edited); // .Include(c => c.Office) is missing
    }
}

---

回答我自己的问题以防对别人有帮助

基于see EF复制当前值，我能够通过几行代码解决问题，示例如下：

public async Task<IActionResult> Edit(Client client_posted)
{
  if (!ModelState.IsValid)
  {

    ModelState.AddModelError("", "Record is missing required values");

    // requery the client entity from our db to get related child entities
    var client_current = await _context.Client
                                        .Include(c => c.Office)
                                        // include 4 or 5 more entities here
                                        .Where(c => c.client_id == client_posted.client_id)
                                        .AsNoTracking()
                                        .SingleOrDefaultAsync();

    // now replace client_current values with client_posted values by

    // 1 - add entity to your db context (we are not saving it)
    _myDbContext.Client.Add(client_posted);

    // 2 - use the db context to extract current values from the client entity posted
    var client_posted_values =_myDbContext.Entry(client_posted).CurrentValues;

    // 3 - copy the extracted values to the client_current we re-queried from db
    _myDbContext.Entry(client_current).CurrentValues.SetValues(client_posted_values);

    // 4 return the view passing client with original values and the attached office entity(ies)
    return View(client_current);
  }
  // otherwise ModelState is valid, do the update here
  ...
  ...
}

public async Task<IActionResult> Edit(Client client_posted)
{
  if (!ModelState.IsValid)
  {

    ModelState.AddModelError("", "Record is missing required values");

    // requery the client entity from our db to get related child entities
    var client_current = await _context.Client
                                        .Include(c => c.Office)
                                        // include 4 or 5 more entities here
                                        .Where(c => c.client_id == client_posted.client_id)
                                        .AsNoTracking()
                                        .SingleOrDefaultAsync();

    // now replace client_current values with client_posted values by

    // 1 - add entity to your db context (we are not saving it)
    _myDbContext.Client.Add(client_posted);

    // 2 - use the db context to extract current values from the client entity posted
    var client_posted_values =_myDbContext.Entry(client_posted).CurrentValues;

    // 3 - copy the extracted values to the client_current we re-queried from db
    _myDbContext.Entry(client_current).CurrentValues.SetValues(client_posted_values);

    // 4 return the view passing client with original values and the attached office entity(ies)
    return View(client_current);
  }
  // otherwise ModelState is valid, do the update here
  ...
  ...
}