MonoRail/Castle.MonoRail.Framework/Attributes/JSONBinderAttribute.cs

   1 // Copyright 2004-2008 Castle Project - http://www.castleproject.org/
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14
  15 namespace Castle.MonoRail.Framework
  16 {
  17         using System;
  18         using System.Reflection;
  19         using Castle.MonoRail.Framework;
  20         using Castle.MonoRail.Framework.Services;
  21
  22         /// <summary>
  23         /// Enables binding of JSON formatted values on POCO objects.
  24         /// </summary>
  25         /// <example>
  26         /// <para>
  27         /// The following demonstrates how to bind a JSON querystring value representing a Car object instance
  28         /// to a POCO Car object instance:
  29         /// </para>
  30         /// The querystring:
  31         /// <code>
  32         /// car={Wheels=4,Year=2007,Model='Cheap'}
  33         /// </code>
  34         /// And you want to bind those values to a instance of yours Car class, which looks like this:
  35         /// <code>
  36         /// public class Car
  37         ///     {
  38         ///             private int wheels, year;
  39         ///             private string model;
  40         ///
  41         ///             public int Wheels
  42         ///             {
  43         ///                     get { return wheels; }
  44         ///                     set { wheels = value; }
  45         ///             }
  46         ///
  47         ///             public int Year
  48         ///             {
  49         ///                     get { return year; }
  50         ///                     set { year = value; }
  51         ///             }
  52         ///
  53         ///             public string Model
  54         ///             {
  55         ///                     get { return model; }
  56         ///                     set { model = value; }
  57         ///             }
  58         ///     }
  59         /// </code>
  60         /// <para>Using the <see cref="JSONBinderAttribute"/> and the <see cref="SmartDispatcherController"/>, all you have to
  61         /// do is to mark the method parameter with the attribute, like the following example:</para>
  62         /// <code>
  63         /// public void MyAction([JSONBinder("car")] Car car)
  64         /// </code>
  65         /// </example>
  66         [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)]
  67         public class JSONBinderAttribute : Attribute, IParameterBinder
  68         {
  69                 private string entryKey;
  70
  71                 /// <summary>
  72                 /// Initializes a new instance of the <see cref="JSONBinderAttribute"/> class.
  73                 /// </summary>
  74                 public JSONBinderAttribute()
  75                 {
  76                 }
  77
  78                 /// <summary>
  79                 /// Initializes a new instance of the <see cref="JSONBinderAttribute"/> class.
  80                 /// </summary>
  81                 /// <param name="entryKey">The entry key, which is the form or
  82                 /// querystring key that identifies the JSON persisted content</param>
  83                 public JSONBinderAttribute(string entryKey)
  84                 {
  85                         if (entryKey == null) throw new ArgumentNullException("entryKey");
  86
  87                         this.entryKey = entryKey;
  88                 }
  89
  90                 /// <summary>
  91                 /// Calculates the param points. Implementors should return value equals or greater than
  92                 /// zero indicating whether the parameter can be bound successfully. The greater the value (points)
  93                 /// the more successful the implementation indicates to the framework
  94                 /// </summary>
  95                 /// <param name="context">The context.</param>
  96                 /// <param name="controller">The controller.</param>
  97                 /// <param name="controllerContext">The controller context.</param>
  98                 /// <param name="parameterInfo">The parameter info.</param>
  99                 /// <returns></returns>
 100                 public int CalculateParamPoints(IEngineContext context, IController controller,
 101                         IControllerContext controllerContext, ParameterInfo parameterInfo)
 102                 {
 103                         EnsureValidEntryKey(parameterInfo.Name);
 104
 105                         return context.Request.Params[entryKey] != null ? 1 : 0;
 106                 }
 107
 108                 /// <summary>
 109                 /// Binds the specified parameter for the action.
 110                 /// </summary>
 111                 /// <param name="context">The context.</param>
 112                 /// <param name="controller">The controller.</param>
 113                 /// <param name="controllerContext">The controller context.</param>
 114                 /// <param name="parameterInfo">The parameter info.</param>
 115                 /// <returns>
 116                 /// A instance based on the JSON values present in the <c>EntryKey</c> or the parameter name.
 117                 /// </returns>
 118                 public object Bind(IEngineContext context, IController controller, IControllerContext controllerContext, ParameterInfo parameterInfo)
 119                 {
 120                         EnsureValidEntryKey(parameterInfo.Name);
 121
 122                         string entryValue = context.Request.Params[entryKey];
 123
 124                         IJSONSerializer serializer = context.Services.JSONSerializer;
 125
 126                         return serializer.Deserialize(entryValue, parameterInfo.ParameterType);
 127                 }
 128
 129                 private void EnsureValidEntryKey(string name)
 130                 {
 131                         if (entryKey == null)
 132                         {
 133                                 entryKey = name;
 134                         }
 135                 }
 136         }
 137 }