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 ?。

如果有人想返回Model属性的Name，以便将错误消息绑定到强类型视图中。

List<ErrorResult> Errors = new List<ErrorResult>();
foreach (KeyValuePair<string, ModelState> modelStateDD in ViewData.ModelState)
{
    string key = modelStateDD.Key;
    ModelState modelState = modelStateDD.Value;

    foreach (ModelError error in modelState.Errors)
    {
        ErrorResult er = new ErrorResult();
        er.ErrorMessage = error.ErrorMessage;
        er.Field = key;
        Errors.Add(er);
    }
}

通过这种方式，您可以将错误与抛出错误的字段绑定在一起。

基于LINQ版本，如果你想将所有错误消息连接到一个字符串中:

string messages = string.Join("; ", ModelState.Values
                                        .SelectMany(x => x.Errors)
                                        .Select(x => x.ErrorMessage));

在您的实现中，您缺少静态类，这应该是。

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

而

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

任何人在寻找asp.net core 3.1。比上面的答案略有更新。我发现这就是[ApiController]返回的内容

 Dictionary<string, List<string>> errors = new Dictionary<string, List<string>>();

                foreach (KeyValuePair<string, ModelStateEntry> kvp in ViewData.ModelState)
                {
                    string key = kvp.Key;
                    ModelStateEntry entry = kvp.Value;

                    if (entry.Errors.Count > 0)
                    {
                        List<string> errorList = new List<string>();
                        foreach (ModelError error in entry.Errors)
                        {
                            errorList.Add(error.ErrorMessage);
                        }

                        errors[key] = errorList;
                    }
                }

                return  new JsonResult(new {Errors = errors});

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>)