我在MVC 2 Web应用程序上间歇性地收到此错误。我的模型没有无参数构造函数，它们看起来像这样：
public AddParentModel(ITracktionDataLayer dataLayer, MessagePasser messager, AuthUserHelper authUser)
{
_model = new PersonAddEditModel(messager, dataLayer, authUser, null);
}
我应该注意我的控制器确实有无参数构造函数。 PersonAddEditModel不直接暴露给MVC。 AddParentModel仅用于使MVC绑定更容易。
由于AddParentModel（以及MVC正在使用的所有其他模型）存在于服务器上，我可以使它们无参数，尽管这会使我的测试方法陷入困境。 关于这一点的奇怪之处在于间歇性地发生。我希望这样的问题能够持续发生但事实并非如此 - 我只是让ELMAH每隔一天发送一封电子邮件不幸的用户收到此错误。
我想知道我的选择是什么。我能看到解决这个问题的最简单的方法是创建一个构造函数重载，只是将这些参数设置为默认对象（我现在可能只是为了解决手头的问题，但我觉得这样做很脏）但是我我希望得到人们的正确处理方式。我对MVC比较陌生。提前谢谢！
编辑：我想在处理完成的[HttpPost]方法中添加它，即使我在视图上使用模型进行MVC编辑，我收到了一个FormCollection和用它来更新模型，而不是让MVC直接编辑模型。
/// <summary>
/// Add this person, then go to the next page where more people can be added.
/// </summary>
/// <param name="model"></param>
/// <returns></returns>
[HttpPost]
public ActionResult Index(FormCollection fc, HttpPostedFileWrapper upload) {
Uri requestUri = !Request.Url.ToString().Contains("/127.0.0.1/") ? Request.Url : new Uri("...");
MessagePasser messager = new MessagePasser();
ITracktionDataLayer dataLayer = DataFactory.GetDataLayer();
AuthUserHelper user = AuthUserHelper.AnonymousWebUserFrom(dataLayer, requestUri);
AddParentModel model = new AddParentModel(dataLayer, messager, user);
if (TryUpdateModel(model, fc) && ModelState.IsValid)
{
...
我也意识到，对于某些模型，我无法创建无参数构造函数，因为一些模型需要在我的数据层，消息传递层和经过身份验证的用户之上和之外添加一些额外的基元。
答案 0 :(得分：1)
我不能使用依赖注入来解决这个问题，因为我正在请求额外的参数，这些参数依赖于构造函数中的用户信息。我的构造函数接受IDataLayer，MessagePasser和AuthUserHelper，这对所有模型都很常见，但我还要求两个int ID，它依赖于一些隐藏的输入字段或查询字符串参数。
因此，我将模型的属性拆分为它自己的类（模型）和实际处理，例如加载和保存到服务类中。该模型只是一个属性包，可以有一个无参数构造函数，而服务类将被调用来填充和保存数据。我希望这个答案可以帮助那些人。
所以，在我之前：
public class EditFamilyMemberModel
{
#region Constructor
public EditFamilyMemberModel(ITracktionDataLayer dataLayer, MessagePasser messager, AuthUserHelper authUser, int originalPersonID, int familyMemberID)
{
_dataLayer = dataLayer;
_originalPerson = new PersonAddEditModel(messager, dataLayer, authUser, originalPersonID);
_model = new PersonAddEditModel(messager, dataLayer, authUser, familyMemberID);
_grades = _dataLayer.GetGradesForOrganization(authUser.OrganizationID, _model.Person.Grade, true).ToArray();
}
#endregion
#region Private
ITracktionDataLayer _dataLayer;
PersonAddEditModel _originalPerson;
PersonAddEditModel _model;
IList<Grade> _grades;
#endregion
#region Properties
#region Read Only
public Person Person
{
get { return _model.Person; }
}
public AuthUserHelper AuthUser
{
get { return _model.AuthUser; }
}
public IList<School> Schools
{
get { return _model.Schools; }
}
public IList<ContactType> ContactTypes
{
get { return _model.ContactTypes; }
}
public IList<string> Genders
{
get { return _model.Genders; }
}
public IList<Grade> Grades
{
get { return /*_model.Grades;*/ _grades; }
}
public IList<USState> USStates
{
get { return _model.USStates; }
}
public IList<PersonType> PersonTypes
{
get { return _model.PersonTypes; }
}
public IList<FamilyRole> FamilyRoles
{
get { return _model.FamilyRoles; }
}
#endregion
[Required]
[StringLength(100)]
public string Address
{
get { return _model.Person.Address; }
set { _model.Person.Address = value; }
}
[StringLength(100)]
public string Address2
{
get { return _model.Person.Address2; }
set { _model.Person.Address2 = value; }
}
[Required]
[StringLength(50)]
public string City
{
get { return _model.Person.City; }
set { _model.Person.City = value; }
}
[Required]
[StringLength(50)]
public string State
{
get { return _model.Person.State; }
set { _model.Person.State = value; }
}
[Required]
[StringLength(50)]
public string Zip
{
get { return _model.Person.Zip; }
set { _model.Person.Zip = value; }
}
[DataType(DataType.Date)]
//[Required]
public DateTime? DOB
{
get { return _model.Person.DOB; }
set { _model.Person.DOB = value; }
}
[Required]
public string Gender
{
get { return _model.Person.Gender; }
set { _model.Person.Gender = value; }
}
[Required]
public string FirstName
{
get { return _model.Person.FirstName; }
set { _model.Person.FirstName = value; }
}
[Required]
public string LastName
{
get { return _model.Person.LastName; }
set { _model.Person.LastName = value; }
}
public int? SchoolID
{
get { return _model.Person.SchoolID; }
set { _model.Person.SchoolID = value; }
}
public int? GradeID
{
get { return _model.Person.Grade; }
set { _model.Person.Grade = value; }
}
public string SpecialNeedsDescription
{
get { return _model.Person.SpecialNeedsDescription; }
set { _model.Person.SpecialNeedsDescription = value; }
}
public string SpecialNeedsSummary
{
get { return _model.Person.SpecialNeedsSummary; }
set { _model.Person.SpecialNeedsSummary = value; }
}
public byte[] PictureData
{
get;
set;
}
public string PictureAction
{
get;
set;
}
#region Membership
[Display(Name = "User Name")]
[DisplayName("User Name")]
[UniqueUserName(ErrorMessage = "The user name specified is already in use, please choose another user name.")]
public string Username { get; set; }
[Display(Name = "Password")]
[DisplayName("Enter a password")]
[StringLength(50, MinimumLength = 6, ErrorMessage = "Password must be at least 6 characters long.")]
public string Password { get; set; }
[DisplayName("Confirm Password")]
[StringLength(50, MinimumLength = 6)]
public string PasswordConfirm { get; set; }
#endregion
#region Abstracted Contact Methods
/// <summary>
/// When adding someone, this represents the phone number contact record.
/// </summary>
[Display(Name = "Home Phone Number")]
[DisplayName("Home Phone Number")]
[USPhoneNumber]
//[Required]
public string HomePhoneNumber
{
get { return _model.HomePhone; }
set { _model.HomePhone = value; }
}
/// <summary>
/// When adding someone, this represents the phone number contact record.
/// </summary>
[Display(Name = "Cell Phone Number")]
[DisplayName("Cell Phone Number")]
[USPhoneNumber]
//[Required]
public string CellPhoneNumber
{
get { return _model.PersonalCell; }
set { _model.PersonalCell = value; }
}
/// <summary>
/// When adding someone, this represents the email address contact record.
/// </summary>
[Display(Name = "Email Address")]
[DisplayName("Email Address")]
//[Required] -- Some parents dont have email addresses
[UniqueEmailAddress(ErrorMessage = "The email address was already found in our system, please sign in or use another email.")]
[Email(ErrorMessage = "The email address specified isn't an email address.")]
public string EmailAddress
{
get { return _model.EmailAddress; }
set { _model.EmailAddress = value; }
}
#endregion
#endregion
#region Logic
public void SaveChanges()
{
_model.Person.ChangedTimeStamp = DateTime.Now;
_model.Person.ChangedBy = -1;
// If we have a valid home #, add it
if (!string.IsNullOrWhiteSpace(HomePhoneNumber))
_model.HomePhone = HomePhoneNumber;
// If we have a valid cell #, add it
if (!string.IsNullOrWhiteSpace(CellPhoneNumber))
_model.PersonalCell = CellPhoneNumber;
// If we have a valid email, add it
if (!string.IsNullOrWhiteSpace(EmailAddress))
_model.EmailAddress = EmailAddress;
// Some fields may have 'not applicable'; blank them
_model.Person.SpecialNeedsDescription = _model.Person.SpecialNeedsDescription.NormalizeNotApplicable().NullIfEmptyOrWhitespace();
_model.Person.SpecialNeedsSummary = _model.Person.SpecialNeedsSummary.NormalizeNotApplicable().NullIfEmptyOrWhitespace();
// Names of people should be proper case if they're all entered in lowercase
_model.Person.FirstName = _model.Person.FirstName.NormalizeName();
_model.Person.LastName = _model.Person.LastName.NormalizeName();
if (PictureData != null && (PictureAction == "replace" || (PictureAction ?? "") == ""))
{
// Replace just adds, it does not remove the old picture.
Photo pic = PhotoHandling.GetPhotoEntityFromBytes(PictureData);
pic.ROWGUID = Guid.NewGuid();
pic.OrganizationID = _model.AuthUser.OrganizationID;
pic.CreationTimestamp = DateTime.Now;
pic.Deleted = false;
_model.AddNewPhoto(pic);
_model.Person.Avatar = pic.ROWGUID;
}
else if (PictureAction == "remove" && _model.Person.Avatar.HasValue)
{
var pic = _model.Person.Photos.SingleOrDefault(p => p.ROWGUID == _model.Person.Avatar.Value);
if (pic != null)
{
pic.Deleted = true;
_model.Person.Avatar = null;
}
}
_model.SaveChanges();
}
#endregion
}
现在我把它分成了：
public class EditFamilyMemberModel
{
public EditFamilyMemberModel() { }
#region Properties
[Required]
[StringLength(100)]
public string Address { get; set; }
[StringLength(100)]
public string Address2 { get; set; }
[Required]
[StringLength(50)]
public string City { get; set; }
[Required]
[StringLength(50)]
public string State { get; set; }
[Required]
[StringLength(50)]
public string Zip { get; set; }
[DataType(DataType.Date)]
//[Required]
public DateTime? DOB { get; set; }
[Required]
public string Gender { get; set; }
[Required]
public string FirstName { get; set; }
[Required]
public string LastName { get; set; }
public int? SchoolID { get; set; }
public int? GradeID { get; set; }
public string SpecialNeedsDescription { get; set; }
public string SpecialNeedsSummary { get; set; }
public byte[] PictureData { get; set; }
public string PictureAction { get; set; }
#region Membership
[Display(Name = "User Name")]
[DisplayName("User Name")]
[UniqueUserName(ErrorMessage = "The user name specified is already in use, please choose another user name.")]
public string Username { get; set; }
[Display(Name = "Password")]
[DisplayName("Enter a password")]
[StringLength(50, MinimumLength = 6, ErrorMessage = "Password must be at least 6 characters long.")]
public string Password { get; set; }
[DisplayName("Confirm Password")]
[StringLength(50, MinimumLength = 6)]
public string PasswordConfirm { get; set; }
#endregion
#region Abstracted Contact Methods
/// <summary>
/// When adding someone, this represents the phone number contact record.
/// </summary>
[Display(Name = "Home Phone Number")]
[DisplayName("Home Phone Number")]
[USPhoneNumber]
//[Required]
public string HomePhoneNumber { get; set; }
/// <summary>
/// When adding someone, this represents the phone number contact record.
/// </summary>
[Display(Name = "Cell Phone Number")]
[DisplayName("Cell Phone Number")]
[USPhoneNumber]
//[Required]
public string CellPhoneNumber { get; set; }
/// <summary>
/// When adding someone, this represents the email address contact record.
/// </summary>
[Display(Name = "Email Address")]
[DisplayName("Email Address")]
//[Required] -- Some parents dont have email addresses
//[UniqueEmailAddress(ErrorMessage = "The email address was already found in our system, please sign in or use another email.")]
[Email(ErrorMessage = "The email address specified isn't an email address.")]
public string EmailAddress { get; set; }
#endregion
#endregion
#region Read-Only Properties
public IList<School> Schools { get; internal set; }
public IList<ContactType> ContactTypes { get; internal set; }
public IList<string> Genders { get; internal set; }
public IList<Grade> Grades { get; internal set; }
public IList<USState> USStates { get; internal set; }
public IList<PersonType> PersonTypes { get; internal set; }
public IList<FamilyRole> FamilyRoles { get; internal set; }
public Person Person { get; internal set; }
#endregion
}
public class EditFamilyMemberService
{
#region Constructor
public EditFamilyMemberService(ITracktionDataLayer dataLayer, MessagePasser messager, AuthUserHelper authUser, int originalPersonID, int familyMemberID)
{
_dataLayer = dataLayer;
_originalPerson = new PersonAddEditModel(messager, dataLayer, authUser, originalPersonID);
_model = new PersonAddEditModel(messager, dataLayer, authUser, familyMemberID);
_grades = _dataLayer.GetGradesForOrganization(authUser.OrganizationID, _model.Person.Grade, true).ToArray();
Model = new EditFamilyMemberModel()
{
Address = _model.Person.Address,
Address2 = _model.Person.Address2,
CellPhoneNumber = _model.PersonalCell,
City = _model.Person.City,
ContactTypes = _model.ContactTypes,
DOB = _model.Person.DOB,
EmailAddress = _model.EmailAddress,
FamilyRoles = _model.FamilyRoles,
FirstName = _model.Person.FirstName,
Gender = _model.Person.Gender,
Genders = _model.Genders,
GradeID = _model.Person.Grade,
Grades = _model.Grades,
HomePhoneNumber = _model.HomePhone,
LastName = _model.Person.LastName,
Password = null,
PasswordConfirm = null,
PersonTypes = _model.PersonTypes,
PictureAction = null,
PictureData = null,
SchoolID = _model.Person.SchoolID,
Schools = _model.Schools,
SpecialNeedsDescription = _model.Person.SpecialNeedsDescription,
SpecialNeedsSummary = _model.Person.SpecialNeedsSummary,
State = _model.Person.State,
Username = null,
USStates = _model.USStates,
Zip = _model.Person.Zip,
Person = _model.Person
};
}
#endregion
#region Private
ITracktionDataLayer _dataLayer;
PersonAddEditModel _originalPerson;
PersonAddEditModel _model;
IList<Grade> _grades;
#endregion
#region Properties
public EditFamilyMemberModel Model { get; internal set; }
#region Read Only
public Person Person
{
get { return _model.Person; }
}
public AuthUserHelper AuthUser
{
get { return _model.AuthUser; }
}
#endregion
#endregion
#region Logic
public void SaveChanges()
{
_model.Person.ChangedTimeStamp = DateTime.Now;
_model.Person.ChangedBy = -1;
// If we have a valid home #, add it
if (!string.IsNullOrWhiteSpace(Model.HomePhoneNumber))
_model.HomePhone = Model.HomePhoneNumber;
// If we have a valid cell #, add it
if (!string.IsNullOrWhiteSpace(Model.CellPhoneNumber))
_model.PersonalCell = Model.CellPhoneNumber;
// If we have a valid email, add it
if (!string.IsNullOrWhiteSpace(Model.EmailAddress))
_model.EmailAddress = Model.EmailAddress;
// Some fields may have 'not applicable'; blank them
Model.SpecialNeedsDescription = Model.SpecialNeedsDescription.NormalizeNotApplicable().NullIfEmptyOrWhitespace();
Model.SpecialNeedsSummary = Model.SpecialNeedsSummary.NormalizeNotApplicable().NullIfEmptyOrWhitespace();
// Names of people should be proper case if they're all entered in lowercase
Model.FirstName = Model.FirstName.NormalizeName();
Model.LastName = Model.LastName.NormalizeName();
// Save this extra information
_model.Person.Address = Model.Address;
_model.Person.Address2 = Model.Address2;
_model.PersonalCell = Model.CellPhoneNumber;
_model.Person.City = Model.City;
_model.Person.DOB = Model.DOB;
_model.EmailAddress = Model.EmailAddress;
_model.Person.FirstName = Model.FirstName;
_model.Person.Gender = Model.Gender;
_model.Person.Grade = Model.GradeID;
_model.HomePhone = Model.HomePhoneNumber;
_model.Person.LastName = Model.LastName;
_model.Person.SchoolID = Model.SchoolID;
_model.Person.SpecialNeedsDescription = Model.SpecialNeedsDescription;
_model.Person.SpecialNeedsSummary = Model.SpecialNeedsSummary;
_model.Person.State = Model.State;
_model.Person.Zip = Model.Zip;
// Save picture data
if (Model.PictureData != null && (Model.PictureAction == "replace" || (Model.PictureAction ?? "") == ""))
{
// Replace just adds, it does not remove the old picture.
Photo pic = PhotoHandling.GetPhotoEntityFromBytes(Model.PictureData);
pic.ROWGUID = Guid.NewGuid();
pic.OrganizationID = _model.AuthUser.OrganizationID;
pic.CreationTimestamp = DateTime.Now;
pic.Deleted = false;
_model.AddNewPhoto(pic);
_model.Person.Avatar = pic.ROWGUID;
}
else if (Model.PictureAction == "remove" && _model.Person.Avatar.HasValue)
{
var pic = _model.Person.Photos.SingleOrDefault(p => p.ROWGUID == _model.Person.Avatar.Value);
if (pic != null)
{
pic.Deleted = true;
_model.Person.Avatar = null;
}
}
_model.SaveChanges();
}
#endregion
}
模型本身不需要任何ctor参数，不应再抛出该错误。我是将相关逻辑和数据封装到单个类中的忠实粉丝，但由于这只是繁重的PersonAddEditModel的包装，并且它只在MVC方面使用，我可以处理这个问题。
如果有人对我刚刚发布的内容有任何意见或选择，我会全力以赴。