ModelState即将失效？

Question

我正在研究MVC5 Code-First应用程序.

在一个型号的Edit()观点我已经包括[Create]按钮,新的价值观从内部添加到其他模型Edit()视图,然后重新填充内的新值DropDownFors()上Edit().

对于第一次尝试,我将model_description通过AJAX 传递给我的控制器方法createNewModel():

[HttpPost]
public JsonResult createNewModel(INV_Models model)
{
    // model.model_description is passed in via AJAX -- Ex. 411

    model.created_date = DateTime.Now;
    model.created_by = System.Environment.UserName;
    model.modified_date = DateTime.Now;
    model.modified_by = System.Environment.UserName;

    // Set ID
    int lastModelId = db.INV_Models.Max(mdl => mdl.Id);
    model.Id = lastModelId+1;

    //if (ModelState.IsValid == false && model.Id > 0)
    //{
    //    ModelState.Clear();
    //}

    // Attempt to RE-Validate [model], still comes back "Invalid"
    TryValidateModel(model);

    // Store all errors relating to the ModelState.
    var allErrors = ModelState.Values.SelectMany(x => x.Errors);

    // I set a watch on [allErrors] and by drilling down into
    // [allErrors]=>[Results View]=>[0]=>[ErrorMessage] I get
    // "The created_by filed is required", which I'm setting....?

    try
    {
        if (ModelState.IsValid)
        {
            db.INV_Models.Add(model);
            db.SaveChangesAsync();
        }

    }
    catch (Exception ex)
    {
        Elmah.ErrorSignal.FromCurrentContext().Raise(ex);
    }

    return Json(
        new { ID = model.Id, Text = model.model_description },
        JsonRequestBehavior.AllowGet);
}

我无法弄清楚为什么我ModelState的出现Invalid？

在ModelState检查之前指定所有属性; 模型定义如下:

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

    [Required(ErrorMessage = "Please enter a Model Description.")]
    public string model_description { get; set; }

    [Required]
    [DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}")]
    public DateTime created_date { get; set; }

    [Required]
    public string created_by { get; set; }

    [DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}")]
    public DateTime modified_date { get; set; }

    public string modified_by { get; set; }
}

---

编辑:

添加了查看代码:

输入表格:

        <span class="control-label col-md-2">Type:</span>
        <div class="col-md-4">
            @Html.DropDownListFor(model => model.Type_Id, (SelectList)ViewBag.Model_List, "<<< CREATE NEW >>>", htmlAttributes: new { @class = "form-control dropdown" })
            @Html.ValidationMessageFor(model => model.Type_Id, "", new { @class = "text-danger" })
        </div>
        <div class="col-md-1">
            <div class="btn-group">
                <button type="button" class="btn btn-success" aria-expanded="false">CREATE NEW</button>
            </div>
        </div>

脚本:

        $('#submitNewModel').click(function () {

            var form = $(this).closest('form');
            var data = { model_description: document.getElementById('textNewModel').value };

            $.ajax({
                type: "POST",
                dataType: "JSON",
                url: '@Url.Action("createNewModel", "INV_Assets")',
                data: data,
                success: function (resp) {
                    alert("SUCCESS!");
                    $('#selectModel').append($('<option></option>').val(resp.ID).text(resp.Text));
                    alert("ID: " + resp.ID + " // New Model: " + resp.Text); // RETURNING 'undefined'...?
                    form[0].reset();
                    $('#createModelFormContainer').hide();
                },
                error: function () {
                    alert("ERROR!");
                }
            });
        });

Answer 1

当您无法快速推断出ModelState验证失败的原因时,快速迭代错误通常很有帮助.

foreach (ModelState state in ModelState.Values.Where(x => x.Errors.Count > 0)) { }

或者,您可以直接提取错误.

var allErrors = ModelState.Values.SelectMany(x => x.Errors);

请记住,ModelState是在Action的主体执行之前构造的.因此,无论您何时在Controller Action中设置模型的属性,都将设置IsValid.

如果您希望灵活地手动设置属性然后重新评估对象的有效性,则可以在设置属性后手动重新运行Action内部的验证.如评论中所述,您应该在尝试重新验证之前清除ModelState.

ModelState.Clear();
ValidateModel(model);

try
{
    if (ModelState.IsValid)
    {
        db.INV_Models.Add(model);
        db.SaveChangesAsync();
    }
}
...

顺便说一句,如果模型仍然无效,ValidateModel(model)将抛出异常.如果您想阻止它,请使用TryValidateMode l,它返回true/false:

protected internal bool TryValidateModel(Object model)