此消息
"Object reference not set to an instance of an object"
。如何捕获此错误消息？
@Html.DropDownListFor(a => a.BrcId, new SelectList(Model.Branches, "BrcId", "BranchName"), "Select Branch")
我有一个RegisterModel类
public class RegisterModel
{
[Required]
[Display(Name="Branch Name")]
public int? BrcId { get; set; }
[Required]
[Display(Name="User Name")]
public string UserName { get; set; }
[Required]
[Display(Name="Password")]
[DataType(DataType.Password)]
[StringLength(20, ErrorMessage="The {0} must be at least {2} characters long.", MinimumLength=6)]
public string Password { get; set; }
[Display(Name="Confirm Password")]
[DataType(DataType.Password)]
[Compare("Password", ErrorMessage="The password and confirmation password do not match.")]
public string ConfirmPassword { get; set; }
[Required]
[Display(Name="LastName")]
public string LastName { get; set; }
[Required]
[Display(Name="First/Middle Name")]
public string FirstMidName { get; set; }
[Required]
[Display(Name="Gender")]
public string Gender { get; set; }
[Required]
[Display(Name="Date of Birth")]
[DataType(DataType.DateTime)]
[DisplayFormat(DataFormatString = "{0:dd-MM-yyyy}", ApplyFormatInEditMode = true)]
public DateTime DateOfBirth { get; set; }
[Required]
[Display(Name="Telephone")]
[DataType(DataType.PhoneNumber)]
[DisplayFormat(ApplyFormatInEditMode=true, DataFormatString="{0:(###) ###-####}")]
public string Telephone { get; set; }
[Required]
[Display(Name="Email")]
[RegularExpression("^[a-zA-Z0-9_\\.-]+@([a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,6}$", ErrorMessage = "Please enter correct email address")]
public string Email { get; set; }
[Required]
[Display(Name="Secret Question")]
public string SecretQuestion { get; set; }
[Required]
[Display(Name="Secret Answer")]
public string SecretAnswer { get; set; }
[Required]
[Display(Name="Status")]
public string Status { get; set; }
[Required]
[Display(Name="Role")]
public string Role { get; set; }
[Required]
[Display(Name = "Created By")]
public string CreatedBy { get; set; }
[Required]
[Display(Name = "Created Date")]
[DataType(DataType.DateTime)]
[DisplayFormat(DataFormatString = "{0:dd-MM-yyyy}", ApplyFormatInEditMode = true)]
public DateTime CreatedDate { get; set; }
public IEnumerable<Branch> Branches { get; set; }
}
和一个名为＆＃34; BasedController＆＃34;其中包含一个动作方法
[Authorize]
public ActionResult Register()
{
var model = new RegisterModel
{
Branches = _db.Branch.ToList()
};
_db.Dispose();
return View(model);
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Register(
[Bind(Include=
"BrcId, UserName, Password, LastName, FirstMidName, Gender, DateOfBirth, Telephone, Email, SecretQuestion, SecretAnswer, Status, Role, CreatedBy, CreatedDate")]
User entry, string returnUrl)
{
try
{
if (ModelState.IsValid)
{
var Obj = _db.User.Where(u => u.UserName.Equals(entry.UserName)).FirstOrDefault();
if (Obj == null) //if current user doesn't exist
{
// Attempt to register the user
_db.User.Add(entry);
_db.SaveChanges();
_db.Dispose();
ModelState.Clear();
return RedirectToAction("Login");
}
else
{
ModelState.AddModelError("", "username is already registerd");
return View();
}
}
}
catch (Exception e)
{
ViewBag.ErrorMessage = e.Message.ToString();
return View("Error");
//ModelState.AddModelError("", e.Message);
}
return View();
}
和一个名为＆＃34; Register.cshtml＆＃34;
的视图@using (Html.BeginForm()) {
@Html.AntiForgeryToken()
<table>
@Html.ValidationSummary(true)
<tr>
<td>
@Html.LabelFor(a => a.BrcId)
</td>
<td>
@Html.DropDownListFor(a => a.BrcId, new SelectList(Model.Branches, "BrcId", "BranchName"), "Select Branch")
</td>
<td>
@Html.ValidationMessageFor(a => a.BrcId)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.UserName)
</td>
<td>
@Html.TextBoxFor(a => a.UserName)
</td>
<td>
@Html.ValidationMessageFor(a => a.UserName)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Password)
</td>
<td>
@Html.PasswordFor(a => a.Password)
</td>
<td>
@Html.ValidationMessageFor(a => a.Password)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.ConfirmPassword)
</td>
<td>
@Html.PasswordFor(a => a.ConfirmPassword)
</td>
<td>
@Html.ValidationMessageFor(a => a.ConfirmPassword)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.LastName)
</td>
<td>
@Html.TextBoxFor(a => a.LastName)
</td>
<td>
@Html.ValidationMessageFor(a => a.LastName)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.FirstMidName)
</td>
<td>
@Html.TextBoxFor(a => a.FirstMidName)
</td>
<td>
@Html.ValidationMessageFor(a => a.FirstMidName)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Gender)
</td>
<td>
@Html.DropDownListFor(a => a.Gender, new List<SelectListItem>
{
new SelectListItem{Text="Male"},
new SelectListItem{Text="Female"}
},"Select Gender")
</td>
<td>
@Html.ValidationMessageFor(a => a.Gender)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.DateOfBirth)
</td>
<td>
@Html.EditorFor(a => a.DateOfBirth)
</td>
<td>
@Html.ValidationMessageFor(a => a.DateOfBirth)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Telephone)
</td>
<td>
@Html.EditorFor(a => a.Telephone)
</td>
<td>
@Html.ValidationMessageFor(a => a.Telephone)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Email)
</td>
<td>
@Html.TextBoxFor(a => a.Email)
</td>
<td>
@Html.ValidationMessageFor(a => a.Email)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.SecretQuestion)
</td>
<td>
@Html.DropDownListFor(a => a.SecretQuestion, new List<SelectListItem>
{
new SelectListItem{Text = "Where is the first place, you met your crush?"},
new SelectListItem{Text = "Who is your favorite teacher?"},
new SelectListItem{Text = "Where is your dream place?"},
new SelectListItem{Text = "What is your favorite color?"},
new SelectListItem{Text = "What is your favorite food?"},
new SelectListItem{Text = "What is your pet's name?"},
new SelectListItem{Text = "What is your favorite spot?"}
}, "Select a Question")
</td>
<td>
@Html.ValidationMessageFor(a => a.SecretQuestion)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.SecretAnswer)
</td>
<td>
@Html.TextBoxFor(a => a.SecretAnswer)
</td>
<td>
@Html.ValidationMessageFor(a => a.SecretAnswer)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Status)
</td>
<td>
@Html.DropDownListFor(a => a.Status, new List<SelectListItem>
{
new SelectListItem{Text="Enable"},
new SelectListItem{Text="Disable"}
},"Select Status")
</td>
<td>
@Html.ValidationMessageFor(a => a.Status)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.Role)
</td>
<td>
@Html.DropDownListFor(a => a.Role, new List<SelectListItem>
{
new SelectListItem{Text="Administrator"},
new SelectListItem{Text="Supervisor"},
new SelectListItem{Text="Staff"}
},"Select Role")
</td>
<td>
@Html.ValidationMessageFor(a => a.Role)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.CreatedBy)
</td>
<td>
@Html.TextBoxFor(a => a.CreatedBy, new { Value = User.Identity.Name, @readonly = "readonly" })
</td>
<td>
@Html.ValidationMessageFor(a => a.CreatedBy)
</td>
</tr>
<tr>
<td>
@Html.LabelFor(a => a.CreatedDate)
</td>
<td>
@Html.TextBoxFor(a => a.CreatedDate, new { Value = @DateTime.Today.Date.ToString("dd-MM-yyyy"), @readonly = "readonly" })
@*@Html.EditorFor(a => a.CreatedDate)*@
</td>
<td>
@Html.ValidationMessageFor(a => a.CreatedDate)
</td>
</tr>
<tr>
<td>
</td>
<td>
<input type="submit" value="Register" />
<input type="reset" value="Reset" />
</td>
<td>
</td>
</tr>
</table>
}