Web Api 模型验证

1.模型建立，在模型上类上添加System.ComponentModel.DataAnnotations验证属性

public class Product
{
        public int Id { get; set; }
        [Required]
        public string Name { get; set; }
        public decimal Price { get; set; }
        [Range(0, 999)]
        public double Weight { get; set; }
}

2.在ApiController类中使用验证结果

 public HttpResponseMessage Post(Product product)
        {
            if (ModelState.IsValid)
            {
                // Do something with the product (not shown).

                return new HttpResponseMessage(HttpStatusCode.OK);
            }
            else
            {
                return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
            }
        }

3.客户端调用并处理验证出错信息

 static async Task RunAsync()
        {
            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri("http://localhost:57332/");
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

              
                // HTTP POST
                var gizmo = new Product() { Name = "Gizmo", Price = 100, Weight = -200 };
                HttpResponseMessage response = await client.PostAsJsonAsync("api/Product", gizmo);

                if (response.IsSuccessStatusCode)
                {
                    // Get the URI of the created resource.
                    Uri gizmoUrl = response.Headers.Location;
                    Console.WriteLine("Post OK!");
                }
                else if (response.StatusCode == HttpStatusCode.BadRequest)
                {                   
                    var x = await response.Content.ReadAsStringAsync();
                    Console.WriteLine(x); //输出出错信息
                
                }
            }
        }

4.利用Filter Attribute来统一处理验证出错信息

建立Filter类

 public class ValidateModelAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            if (actionContext.ModelState.IsValid == false)
            {
                actionContext.Response = actionContext.Request.CreateErrorResponse(
                    HttpStatusCode.BadRequest, actionContext.ModelState);
            }
        }

在WebApiConfig.cs中添加如下代码

public static void Register(HttpConfiguration config)
{
            
      config.Filters.Add(new ValidateModelAttribute()); //将这行代码添加进去
 }

这样action中就可以直接写验证通过后的业务逻辑了，在每个action不需要单独使用 if (ModelState.IsValid)方法来判断了，代码变得简洁明了

 [ValidateModel]
    public HttpResponseMessage Post(Product product)
    {
         // Do something with the product (not shown).

                return new HttpResponseMessage(HttpStatusCode.OK);
    }

5.验证效果

响应信息

{StatusCode: 400, ReasonPhrase: 'Bad Request', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
  Pragma: no-cache
  X-SourceFiles: =?UTF-8?B?ZDpcbXkgZG9jdW1lbnRzXHZpc3VhbCBzdHVkaW8gMjAxM1xQcm9qZWN0c1xNb2RlbFZhbGlkYXRpb25EZW1vXE1vZGVsVmFsaWRhdGlvbkRlbW9cYXBpXFByb2R1Y3Q=?=
  Cache-Control: no-cache
  Date: Thu, 07 Apr 2016 14:12:21 GMT
  Server: Microsoft-IIS/8.0
  X-AspNet-Version: 4.0.30319
  X-Powered-By: ASP.NET
  Content-Length: 109
  Content-Type: application/json; charset=utf-8
  Expires: -1
}}

返回XML类型出错信息

返回json格式数据

{"Message":"请求无效。","ModelState":{"product.Weight":["字段 Weight 必须在 0 和 999 之间。"]}}