class/System.Web.Mvc/System.Web.Mvc/ModelBinders.cs

   1 /* ****************************************************************************
   2  *
   3  * Copyright (c) Microsoft Corporation. All rights reserved.
   4  *
   5  * This software is subject to the Microsoft Public License (Ms-PL).
   6  * A copy of the license can be found in the license.htm file included
   7  * in this distribution.
   8  *
   9  * You must not remove this notice, or any other, from this software.
  10  *
  11  * ***************************************************************************/
  12
  13 namespace System.Web.Mvc {
  14     using System;
  15     using System.Reflection;
  16     using System.Web;
  17
  18     public static class ModelBinders {
  19
  20         private static readonly ModelBinderDictionary _binders = CreateDefaultBinderDictionary();
  21
  22         public static ModelBinderDictionary Binders {
  23             get {
  24                 return _binders;
  25             }
  26         }
  27
  28         internal static IModelBinder GetBinderFromAttributes(ICustomAttributeProvider element, Func<string> errorMessageAccessor) {
  29             // this method is used to get a custom binder based on the attributes of the element passed to it.
  30             // it will return null if a binder cannot be detected based on the attributes alone.
  31
  32             CustomModelBinderAttribute[] attrs = (CustomModelBinderAttribute[])element.GetCustomAttributes(typeof(CustomModelBinderAttribute), true /* inherit */);
  33             if (attrs == null) {
  34                 return null;
  35             }
  36
  37             switch (attrs.Length) {
  38                 case 0:
  39                     return null;
  40
  41                 case 1:
  42                     IModelBinder binder = attrs[0].GetBinder();
  43                     return binder;
  44
  45                 default:
  46                     string errorMessage = errorMessageAccessor();
  47                     throw new InvalidOperationException(errorMessage);
  48             }
  49         }
  50
  51         private static ModelBinderDictionary CreateDefaultBinderDictionary() {
  52             // We can't add a binder to the HttpPostedFileBase type as an attribute, so we'll just
  53             // prepopulate the dictionary as a convenience to users.
  54
  55             ModelBinderDictionary binders = new ModelBinderDictionary() {
  56                 { typeof(HttpPostedFileBase), new HttpPostedFileBaseModelBinder() }
  57             };
  58             return binders;
  59         }
  60
  61     }
  62 }