在之前的一篇文章中提到，storage类库中包含一个可以用来动态获取Azure table storage 表结构的类-DynamicTableEntity。

我们可以通过这个类，我们无需为每一个表提前声明一个class，也能够对其进行操作。

但在我们要添加Entity到表中的时候会感觉到一点不舒服

以下我所希望使用的该类的方式：

dynamic entity = new DynamicTableEntity();entity.Name=”sam”;entity.Gender=true;…

这样的形式

而实际代码却是

DynamicTableEntity entity1 = new DynamicTableEntity();            Dictionary
     
       data1 = new Dictionary
      
       ();            data1.Add("Name", new EntityProperty("Sam"));            data1.Add("Gender", new EntityProperty(true));            data1.Add("Age", new EntityProperty(18));            entity1.Properties = data1;            entity1.PartitionKey = "Partition1";            entity1.RowKey = "1";            UserDataList.Add(entity1);
      
     

　　

身为一个以dynamic开头的类居然不能够用dynamic关键字来初始化它，在实例化一个DynamicTableEntity类的时候居然要如此麻烦，实在让人不爽。

所以， 经过一番研究，发现了一个可以支持动态扩展的类，为了与DynamicTableEntity区分开来，所以取名DynamicObjectTableEntity。它实现了DynamicTableEntity相同的功能，而且继承了DynamicObject，从而具有动态语言的特性，更加方便 使用。

而且动态语言扩展一直以来除了在linq中使用比较多以外，其它地方基本看不到。这里正好通过对dynamicTableEntity的改造可以加深对动态语言扩展的理解。

实现代码如下：

public class DynamicObjectTableEntity : DynamicObject,ITableEntity    {        #region DynamicTableEntity's code        // Methods        public DynamicObjectTableEntity()        {            this.Properties = new Dictionary
     
      ();        }        public DynamicObjectTableEntity(string partitionKey, string rowKey) : this(partitionKey, rowKey, DateTimeOffset.MinValue, null, new Dictionary
      
       ())        {        }        public DynamicObjectTableEntity(string partitionKey, string rowKey, string etag, IDictionary
       
         properties) : this(partitionKey, rowKey, DateTimeOffset.MinValue, etag, properties)        {        }        internal DynamicObjectTableEntity(string partitionKey, string rowKey, DateTimeOffset timestamp, string etag, IDictionary
        
          properties)        {            //CommonUtility.AssertNotNull("partitionKey", partitionKey);            //CommonUtility.AssertNotNull("rowKey", rowKey);            //CommonUtility.AssertNotNull("properties", properties);            this.PartitionKey = partitionKey;            this.RowKey = rowKey;            this.Timestamp = timestamp;            this.ETag = etag;            this.Properties = properties;        }        public void ReadEntity(IDictionary
         
           properties, OperationContext operationContext)        {            this.Properties = properties;        }        public IDictionary
          
            WriteEntity(OperationContext operationContext) { return this.Properties; } // Properties public string ETag { get; set; } public EntityProperty this[string key] { get { return this.Properties[key]; } set { this.Properties[key] = value; } } public string PartitionKey { get; set; } public IDictionary
           
             Properties { get; set; } public string RowKey { get; set; } public DateTimeOffset Timestamp { get; set; } #endregion #region override DynamicObject's mehtods public override bool TryGetMember(GetMemberBinder binder, out object result) { if (!Properties.ContainsKey(binder.Name)) Properties.Add(binder.Name, ConvertToEntityProperty(binder.Name, null)); result = Properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { EntityProperty property = ConvertToEntityProperty(binder.Name, value); if (Properties.ContainsKey(binder.Name)) Properties[binder.Name] = property; else Properties.Add(binder.Name, property); return true; } /// 
            
 /// Convert object value to EntityProperty. /// 
 private EntityProperty ConvertToEntityProperty(string key, object value) { if (value == null) return new EntityProperty((string)null); if (value.GetType() == typeof(byte[])) return new EntityProperty((byte[])value); if (value.GetType() == typeof(bool)) return new EntityProperty((bool)value); if (value.GetType() == typeof(DateTimeOffset)) return new EntityProperty((DateTimeOffset)value); if (value.GetType() == typeof(DateTime)) return new EntityProperty((DateTime)value); if (value.GetType() == typeof(double)) return new EntityProperty((double)value); if (value.GetType() == typeof(Guid)) return new EntityProperty((Guid)value); if (value.GetType() == typeof(int)) return new EntityProperty((int)value); if (value.GetType() == typeof(long)) return new EntityProperty((long)value); if (value.GetType() == typeof(string)) return new EntityProperty((string)value); throw new Exception("This value type" + value.GetType() + " for " + key); throw new Exception(string.Format("This value type {0} is not supported for {1}", key)); } /// 
            
 /// Get the edm type, if the type is not a edm type throw a exception. /// 
 private Type GetType(EdmType edmType) { switch (edmType) { case EdmType.Binary: return typeof(byte[]); case EdmType.Boolean: return typeof(bool); case EdmType.DateTime: return typeof(DateTime); case EdmType.Double: return typeof(double); case EdmType.Guid: return typeof(Guid); case EdmType.Int32: return typeof(int); case EdmType.Int64: return typeof(long); case EdmType.String: return typeof(string); default: throw new TypeLoadException(string.Format("not supported edmType:{0}", edmType)); } } #endregion }
           
          
         
        
       
      
     

　

在使用了如下类之后，我们就可以用我预期的代码来操作table 了

代码如下：

static void Main(string[] args)        {            var connectionString = "DefaultEndpointsProtocol=https;AccountName=[Account];AccountKey=[Key]";            CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connectionString);            try            {                var client = storageAccount.CreateCloudTableClient();                var table = client.GetTableReference("ShortMessages");                table.CreateIfNotExists();                dynamic entity = new DynamicObjectTableEntity("default", DateTime.Now.ToShortTimeString());                entity.Name = "pete";                entity.Message = "Hello";                table.Execute(TableOperation.Insert(entity));                Console.WriteLine("insert successfully!");            }            catch (Exception ex)            {                Console.WriteLine(ex.Message);            }            Console.Read();            }

　　

示例参考MSDN：