这个代码片段也很有用，它为您提供了一个包含错误消息的列表。

var errors = ModelState.Values。SelectMany(x => x. errors。Select(c => c. errormessage)).ToList();

foreach (ModelState modelState in ViewData.ModelState.Values) {
    foreach (ModelError error in modelState.Errors) {
        DoSomethingWith(error);
    }
}

请参见如何在ASP中获取模型状态错误的集合。净MVC ?。

对于AJAX请求更好的解决方案:

    public IActionResult Demo(DemoInfo formData)
    {
        if (!ModelState.IsValid)
        {
            IEnumerable<object> formErrors = ModelState.Select((s) => new { 
                fieldName = s.Key, 
                fieldValue = s.Value.RawValue,
                fieldMessage = s.Value.Errors.FirstOrDefault()?.ErrorMessage
            });
            return Json(new { formValid = 0, formErrors });
        }
        return Json(new { formValid = 1 });
    }

回应格式为:

{"formValid":0,
 "formErrors":[{
     "fieldName":"name of field from object",
     "fieldValue":"value from browser",
     "fieldMessage":null /*Error message from model annotations if field is valid the value will be null */
 }]
}

有关Func<>的更多详细信息，请查看本页:Func<TSource,Int32,TResult>)

这个也有用:

var query = from state in ModelState.Values
    from error in state.Errors
    select error.ErrorMessage;
var errors = query.ToArray(); // ToList() and so on...

这是对@Dunc的回答的扩展。参见xml文档注释

// ReSharper disable CheckNamespace
using System.Linq;
using System.Web.Mvc;


public static class Debugg
{
    /// <summary>
    /// This class is for debugging ModelState errors either in the quick watch 
    /// window or the immediate window.
    /// When the model state contains dozens and dozens of properties, 
    /// it is impossible to inspect why a model state is invalid.
    /// This method will pull up the errors
    /// </summary>
    /// <param name="modelState">modelState</param>
    /// <returns></returns>
    public static ModelError[]  It(ModelStateDictionary modelState)
    {
        var errors = modelState.Values.SelectMany(x => x.Errors).ToArray();
        return errors;            
    }
}

我可以用一点LINQ来做这个，

public static List<string> GetErrorListFromModelState
                                              (ModelStateDictionary modelState)
{
      var query = from state in modelState.Values
                  from error in state.Errors
                  select error.ErrorMessage;

      var errorList = query.ToList();
      return errorList;
}

上面的方法返回一个验证错误列表。

进一步阅读:

如何在ASP中读取ModelState中的所有错误。NET MVC