问一个或多个实体的验证失败。有关更多详细信息，请参见'EntityValidationErrors‘属性。ASP.NET MVC
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Stack Overflow用户

提问于 2018-10-15 23:38:46

回答 3查看 171关注 0票数 -2

我遇到了显示为我的标题的错误。我试图寻找解决方案，但我得到的都是关于使用try catch代码块的解决方案。

我一直在使用我制作的课程文档来指导我做这个项目，但这次我遇到的错误，我不知道哪个部分出了问题，以及如何检查错误的部分。

我用// strange注释了它有两个部分，这意味着我不知道错误是在哪里发生的，或者类似的东西。

感谢您阅读我的问题。

这是我的PetRescued模型

public class PetRescued
{
    public int Id { get; set; }

    [Required]
    [StringLength(255)]
    public string PetName { get; set; }

    public int PetAge { get; set; }

    [Required]
    [StringLength(6)]
    public string PetGender { get; set; }

    public short PetWeightInKg { get; set; }

    public DateTime DateWhenRescued { get; set; }

    public PetSpecies PetSpecies { get; set; }

    public byte PetSpeciesId { get; set; }

}

这是我的PetRescued控制器

 public ActionResult New() //populate form
    {
        var petspecies = _context.PetSpecieses.ToList();

        var viewModel = new PetRescuedViewModel
        {
            PetSpecies = petspecies
        };

        return View("PetRescued", viewModel);
    }

[HttpPost]
public ActionResult Save(PetRescued petRescued)
{
    if (petRescued.Id == 0)
        _context.PetRescueds.Add(petRescued);
    else
    {
        var petRescuedInDb = _context.PetRescueds.Single(c => c.Id == petRescued.Id);
        petRescuedInDb.PetName = petRescued.PetName;
        petRescuedInDb.PetAge = petRescued.PetAge;
        petRescuedInDb.PetGender = petRescued.PetGender;
        petRescuedInDb.PetWeightInKg = petRescued.PetWeightInKg;
        petRescuedInDb.PetSpeciesId = petRescued.PetSpeciesId; //strange
        petRescuedInDb.DateWhenRescued = petRescued.DateWhenRescued;
     }

    _context.SaveChanges();
    return RedirectToAction("Index", "PetRescued");
}

This is my PetRescued ViewModel (这是我的PetRescued ViewModel)

public class PetRescuedViewModel
{
    public IEnumerable<PetSpecies> PetSpecies { get; set; }

    public PetRescued PetRescueds { get; set; }


    public PetRescuedViewModel()
    {
        PetRescueds = new PetRescued(); 
    }
}

这是我的PetRescued表单

@using (Html.BeginForm("Save", "PetRescued"))
{
<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetName)
    @Html.TextBoxFor(m => m.PetRescueds.PetName, new { @class = "form-control" })
</div>

//strange
<div class="form-group">
    @Html.LabelFor(m => m.PetSpecies)
    @Html.DropDownListFor(m => m.PetRescueds.PetSpeciesId, new SelectList(Model.PetSpecies, "Id", "SpeciesName"), "Select A Species", new {@class = "form-control"})    
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetAge)
    @Html.TextBoxFor(m => m.PetRescueds.PetAge, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetGender)
    @Html.TextBoxFor(m => m.PetRescueds.PetGender, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetWeightInKg)
    @Html.TextBoxFor(m => m.PetRescueds.PetWeightInKg, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.DateWhenRescued)
    @Html.TextBoxFor(m => m.PetRescueds.DateWhenRescued, "{0:d MMM yyyy}", new { @class = "form-control" }) 
</div>

@Html.HiddenFor(m => m.PetRescueds.Id)
<button type="submit" class="btn btn-primary">Save</button>
}

asp.net

asp.net-mvc

asp.net-mvc-4

asp.net-mvc-5

回答 3

Stack Overflow用户

回答已采纳

发布于 2018-10-16 03:28:43

查看您的模型定义

// This means this value is required 
// and should not be greater than 255 characters 
[Required]
[StringLength(255)]
public string PetName { get; set; }

// This means this value is required 
// and should not be greater than 6 characters 
[Required]
[StringLength(6)]
public string PetGender { get; set; }

因此，要么你没有从你的客户端应用程序发送一个值，要么它超过了你声明的限制。将您的操作方法更改为此以在后端验证您的模型(您永远不应该信任客户端的输入)

[HttpPost]
public ActionResult Save(PetRescued petRescued)
{
    if (ModelState.IsValid) // Check for errors
    {
        if (petRescued.Id == 0)
            _context.PetRescueds.Add(petRescued);
        else
        {
            var petRescuedInDb = _context.PetRescueds.Single(c => c.Id == petRescued.Id);
            petRescuedInDb.PetName = petRescued.PetName;
            petRescuedInDb.PetAge = petRescued.PetAge;
            petRescuedInDb.PetGender = petRescued.PetGender;
            petRescuedInDb.PetWeightInKg = petRescued.PetWeightInKg;
            petRescuedInDb.PetSpeciesId = petRescued.PetSpeciesId; //strange
            petRescuedInDb.DateWhenRescued = petRescued.DateWhenRescued;
         }

        _context.SaveChanges();
        return RedirectToAction("Index", "PetRescued");
    }
    else
        return View(petRescued); // Return the same view with the original data
                                 // or with the correct model of your view, at least
}

更新

更正视图模型以反映正确的数据。这意味着，请确保将正确的模型发送到后端。ASP.Net MVC有一个叫做模型绑定的东西，它是用来将从客户端接收的数据转换成C#模型的机制。默认情况下，它的工作方式是检测从客户端传递的值的名称，并找到与模型属性的精确映射。这意味着在您的视图中，您声明了这一点

    @Html.TextBoxFor(m => m.PetRescueds.PetName, new { @class = "form-control" })

因此，如果您检查浏览器发送的数据，您将看到表单数据包含如下内容

PetRescueds.PetAge: whatever_the_client_typed

该不会被映射到您的模型，因为您的模型没有一个名为PetRescueds的属性和一个名为PetName的子属性，您的操作模型直接是一个PetRescued模型。因此，可以通过直接指定名称attr来更改视图，如下所示

    @Html.TextBox("PetName", Model.PetRescueds.PetName, new { @class = "form-control" })

或者更改您的操作模型以反映视图模型定义。无论哪种方式，您的视图模型都应该在您的操作和视图中保持一致。否则，您将最终在操作模型中接收空值，尽管它们在视图上正确填充，或者在视图中显示空值，而不管您在控制器操作上实际创建了什么。

因此，基本上，请检查您的模型定义。确保使用正确的模型定义显示在视图中。确保您的视图被正确地定义为您期望在后端控制器中接收的内容。

然后，更改视图以包含从服务器检索到的验证错误

@using (Html.BeginForm("Save", "PetRescued"))
{
<!-- This will show your errors-->
@Html.ValidationSummary()
<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetName)
    <!-- Or you can show errors for each model property -->
    <!-- like this -->
    @Html.ValidationMessageFor(m => m.PetRescueds.PetName);
    @Html.TextBox("PetName", Model.PetRescueds.PetName, new { @class = "form-control" })
</div>

//strange
<div class="form-group">
    @Html.LabelFor(m => m.PetSpecies)
    @Html.DropDownListFor(m => m.PetRescueds.PetSpeciesId, new SelectList(Model.PetSpecies, "Id", "SpeciesName"), "Select A Species", new {@class = "form-control"})    
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetAge)
    @Html.TextBoxFor(m => m.PetRescueds.PetAge, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetGender)
    @Html.TextBoxFor(m => m.PetRescueds.PetGender, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.PetWeightInKg)
    @Html.TextBoxFor(m => m.PetRescueds.PetWeightInKg, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(m => m.PetRescueds.DateWhenRescued)
    @Html.TextBoxFor(m => m.PetRescueds.DateWhenRescued, "{0:d MMM yyyy}", new { @class = "form-control" }) 
</div>

@Html.HiddenFor(m => m.PetRescueds.Id)
<button type="submit" class="btn btn-primary">Save</button>
}

您可以在Microsofts's上阅读有关数据验证的更多信息

票数 0

Stack Overflow用户

发布于 2018-10-16 00:14:59

让我们试着解决这个问题。

首先，让我们更改您的控制器，以便能够对模型绑定器返回的错误执行某些操作。

[HttpGet]
public ActionResult New() //populate form
{
    var petspecies = _context.PetSpecieses.ToList();

    var viewModel = new PetRescuedViewModel
    {
        PetSpecies = petspecies
    };

    return View("PetRescued", viewModel);
}

[HttpPost]
public ActionResult Save(PetRescuedViewModel viewModel)
{
    if (ModelState.IsValid) // Check for errors
    {
        if (petRescued.Id == 0)
            _context.PetRescueds.Add(petRescued);
        else
        {
            var petRescuedInDb = _context.PetRescueds.Single(c => c.Id == petRescued.Id);
            petRescuedInDb.PetName = viewModel.PetRescued.PetName;
            petRescuedInDb.PetAge = viewModel.PetRescued.PetAge;
            petRescuedInDb.PetGender = viewModel.PetRescued.PetGender;
            petRescuedInDb.PetWeightInKg = viewModel.PetRescued.PetWeightInKg;
            petRescuedInDb.PetSpeciesId = viewModel.PetRescued.PetSpeciesId; //strange
            petRescuedInDb.DateWhenRescued = viewModel.PetRescued.DateWhenRescued;
        }

        _context.SaveChanges();
        return RedirectToAction("Index", "PetRescued");
    }

    viewModel.PetSpecies = _context.PetSpecieses.ToList();  // populate the list again as the contents are lost when the form is submitted.

    return View("PetRescued", viewModel); // validation errors found, so redisplay the same view
}

然后，更改视图以显示错误。我们基本上是在做this answer建议的事情。

@using (Html.BeginForm("Save", "PetRescued"))
{
    // Displays a summary of all the errors.
    @Html.ValidationSummary() 

    <div class="form-group">
        @Html.LabelFor(m => m.PetRescueds.PetName)
        @Html.TextBoxFor(m => m.PetRescueds.PetName, new { @class = "form-control" })
        // Or you can add this to each property            
        @Html.ValidationMessageFor(m => m.PetRescueds.PetName) 
    </div>

    //strange
    <div class="form-group">
        @Html.LabelFor(m => m.PetSpecies)
        @Html.DropDownListFor(m => m.PetRescueds.PetSpeciesId, new SelectList(Model.PetSpecies, "Id", "SpeciesName"), "Select A Species", new {@class = "form-control"})    
    </div>

    <div class="form-group">
        @Html.LabelFor(m => m.PetRescueds.PetAge)
        @Html.TextBoxFor(m => m.PetRescueds.PetAge, new { @class = "form-control" })
    </div>

    <div class="form-group">
        @Html.LabelFor(m => m.PetRescueds.PetGender)
        @Html.TextBoxFor(m => m.PetRescueds.PetGender, new { @class = "form-control" })
    </div>

    <div class="form-group">
        @Html.LabelFor(m => m.PetRescueds.PetWeightInKg)
        @Html.TextBoxFor(m => m.PetRescueds.PetWeightInKg, new { @class = "form-control" })
    </div>

    <div class="form-group">
        @Html.LabelFor(m => m.PetRescueds.DateWhenRescued)
        @Html.TextBoxFor(m => m.PetRescueds.DateWhenRescued, "{0:d MMM yyyy}", new { @class = "form-control" }) 
    </div>

    @Html.HiddenFor(m => m.PetRescueds.Id)
    <button type="submit" class="btn btn-primary">Save</button>
}

上面的更改至少会让你知道哪些属性有问题。

下一步将是解决实际问题。如果您执行上述操作，但无法进一步弄清楚，请让我知道它是哪些属性，我会看一看。

我猜是public byte PetSpeciesId { get; set; }，但让我们来看看。

希望这能有所帮助。

票数 0

Stack Overflow用户

发布于 2018-10-16 16:20:29

您应该使用try和catch方法来查看导致'EntityValidationErrors‘的字段：

ActionResult保存=>

    try
    {
        _context.SaveChanges();;
    }
    catch (DbEntityValidationException ex)
    {
        var sb = new StringBuilder();

        foreach (var failure in ex.EntityValidationErrors)
        {
            sb.AppendFormat("{0} failed validation\n", failure.Entry.Entity.GetType());
            foreach (var error in failure.ValidationErrors)
            {
                sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
                sb.AppendLine();
            }
        }

        throw new DbEntityValidationException(
            "Entity Validation Failed - errors follow:\n" +
            sb.ToString(), ex
            );
    }

然后，您将知道哪些记录执行了异常。

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/52820231

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