未使用自定義模型綁定器觸發Web API驗證

Question

我正在使用Web API 5構建Web Service。我通過擴展IModelBinder接口來實現自定義模型綁定器，以將複雜類型映射爲參數以採取行動。綁定部分工作正常。但是模型驗證不會發生。 ModelState.IsValid始終爲true。

public class PagingParamsVM 
{ 
     [Range(1, Int32.MaxValue, ErrorMessage = "Page must be at least 1")] 
     public int? Page { get; set; } 

     [Range(1, Int32.MaxValue, ErrorMessage = "Page size must be at least 1")] 
     public int? PageSize { get; set; } 
} 

public class PaginationModelBinder : IModelBinder 
{ 
     public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext) 
     { 
       var model = (PagingParamsVM)bindingContext.Model ?? new PagingParamsVM(); 
       //model population logic 
       ..... 

       bindingContext.Model = model; 
       return true; 
     } 
} 

public IEnumerable<NewsItemVM> Get([ModelBinder(typeof(PaginationModelBinder))]PagingParamsVM pegination) 
{ 
      //Validate(pegination); //if I call this explicitly ModelState.IsValid is set correctly. 
      var valid = ModelState.IsValid; //this is always true 
} 

public class ModelStateValidationActionFilter : ActionFilterAttribute 
{ 
     public override void OnActionExecuting(HttpActionContext actionContext) 
     { 
      var valid = actionContext.ModelState.IsValid //this is always true. 
     } 
} 

如果我顯式調用Validate（）或使用[FromUri]屬性，則ModelState.IsValid設置正確。

public IEnumerable<NewsItemVM> Get([FromUri]PagingParamsVM pegination) 
{ 
      var valid = ModelState.IsValid; 
} 

我是否應該在模型聯編程序中實現驗證部分。如果是的話，我應該如何執行？

Answer 1

我找到了答案。默認驗證過程可以在自定義模型綁定器中調用如下，

public abstract class PaginationModelBinder : IModelBinder 
{ 
     public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext) 
     { 
       var model = (PagingParamsVM)bindingContext.Model ?? new PagingParamsVM(); 
       //model population logic 
       ..... 

       bindingContext.Model = model; 

       //following lines invoke default validation on model 
       bindingContext.ValidationNode.ValidateAllProperties = true; 
       bindingContext.ValidationNode.Validate(actionContext); 

       return true; 
     } 
} 

謝謝大家的支持。

Answer 2

DefaultModelBinder.CreateModel應該幫助你保持模型的狀態：

使用粘結劑可以

public class PaginationModelBinder : DefaultModelBinder 
{ 
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, Type modelType) 
    { 
     if(modelType == typeof(PagingParamsVM)) 
     { 
      var page = default(int?); 
      var model = bindingContext.Model; 
      var valueProvider = bindingContext.ValueProvider; 
      var pageValue = valueProvider.GetValue("Page"); 
      var tmp = default(int); 
      if(pageValue != null && int.TryParse(pageValue.AttemptedValue, out tmp)) 
      { 
       page = tmp; 
      } 

      var pageSize = default(int?); 
      var sizeValue = valueProvider.GetValue("PageSize"); 
      if(sizeValue != null && int.TryParse(sizeValue.AttemptedValue, out tmp)) 
      { 
       pageSize = tmp; 
      } 
      return new PagingParamsVM { Page = page, PageSize = pageSize }; 
     } 
     return base.CreateModel(controllerContext, bindingContext, modelType); 
    } 
} 

的Web API控制器：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Web.Http; 
using System.Web.Mvc; 

public class NewsItemController : ApiController 
{ 
    public IEnumerable<NewsItemVM> Get([ModelBinder(typeof(PaginationModelBinder))]PagingParamsVM pegination) 
    { 
     //Validate(pegination); //if I call this explicitly ModelState.IsValid is set correctly. 
     var valid = ModelState.IsValid; //this is always true 
     return Enumerable.Empty<NewsItemVM>(); 
    } 
}