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...

为了以防有人需要它，我在我的项目中创建并使用下面的静态类

使用的例子:

if (!ModelState.IsValid)
{
    var errors = ModelState.GetModelErrors();
    return Json(new { errors });
}

Usings:

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Mvc;
using WebGrease.Css.Extensions;

类:

public static class ModelStateErrorHandler
{
    /// <summary>
    /// Returns a Key/Value pair with all the errors in the model
    /// according to the data annotation properties.
    /// </summary>
    /// <param name="errDictionary"></param>
    /// <returns>
    /// Key: Name of the property
    /// Value: The error message returned from data annotation
    /// </returns>
    public static Dictionary<string, string> GetModelErrors(this ModelStateDictionary errDictionary)
    {
        var errors = new Dictionary<string, string>();
        errDictionary.Where(k => k.Value.Errors.Count > 0).ForEach(i =>
        {
            var er = string.Join(", ", i.Value.Errors.Select(e => e.ErrorMessage).ToArray());
            errors.Add(i.Key, er);
        });
        return errors;
    }

    public static string StringifyModelErrors(this ModelStateDictionary errDictionary)
    {
        var errorsBuilder = new StringBuilder();
        var errors = errDictionary.GetModelErrors();
        errors.ForEach(key => errorsBuilder.AppendFormat("{0}: {1} -", key.Key,key.Value));
        return errorsBuilder.ToString();
    }
}

此外，ModelState.Values.ErrorMessage可能为空，但ModelState.Values.Exception.Message可能指示一个错误。

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>)

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 ?。

仅仅输出错误消息本身对我来说是不够的，但是这样做达到了目的。

var modelQuery = (from kvp in ModelState
                  let field = kvp.Key
                  let state = kvp.Value
                  where state.Errors.Count > 0
                  let val = state.Value?.AttemptedValue ?? "[NULL]"

                  let errors = string.Join(";", state.Errors.Select(err => err.ErrorMessage))
                  select string.Format("{0}:[{1}] (ERRORS: {2})", field, val, errors));

Trace.WriteLine(string.Join(Environment.NewLine, modelQuery));