Windows Azure Table Storage
does not support是十进制数据类型.
A suggested workaround是使用自定义属性将十进制属性序列化为字符串：
[EntityDataType(PrimitiveTypeKind.String)]
public decimal Quantity { get; set; }
如何实现此EntityDataType自定义属性,从而可以从Windows Azure Tables存储和检索十进制属性？
解决方法
您可以覆盖TableEntity中的WriteEntity方法,并使用EntityResolver
public class CustomTableEntity : TableEntity
{
private const string DecimalPrefix = "D_";
public override IDictionary<string,EntityProperty> WriteEntity(OperationContext operationContext)
{
var entityProperties = base.WriteEntity(operationContext);
var objectProperties = GetType().GetProperties();
foreach (var item in objectProperties.Where(f => f.PropertyType == typeof (decimal)))
{
entityProperties.Add(DecimalPrefix + item.Name,new EntityProperty(item.GetValue(this,null).ToString()));
}
return entityProperties;
}
}
我们将使用的实体
public class MyEntity : CustomTableEntity
{
public string MyProperty { get; set; }
public decimal MyDecimalProperty1 { get; set; }
public decimal MyDecimalProperty2 { get; set; }
}
#region connection
CloudStorageAccount account = CloudStorageAccount.DevelopmentStorageAccount;
CloudTableClient client = account.CreateCloudTableClient();
CloudTable table = client.GetTableReference("mytable");
table.CreateIfNotExists();
#endregion
const string decimalPrefix = "D_";
const string partitionKey = "BlaBlaBla";
string rowKey = DateTime.Now.ToString("yyyyMMddHHmmss");
#region Insert
var entity = new MyEntity
{
PartitionKey = partitionKey,RowKey = rowKey,MyProperty = "Test",MyDecimalProperty1 = (decimal) 1.2,MyDecimalProperty2 = (decimal) 3.45
};
TableOperation insertOperation = TableOperation.Insert(entity);
table.Execute(insertOperation);
#endregion
#region Retrieve
EntityResolver<MyEntity> myEntityResolver = (pk,rk,ts,props,etag) =>
{
var resolvedEntity = new MyEntity {PartitionKey = pk,RowKey = rk,Timestamp = ts,ETag = etag};
foreach (var item in props.Where(p => p.Key.StartsWith(decimalPrefix)))
{
string realPropertyName = item.Key.Substring(decimalPrefix.Length);
System.Reflection.PropertyInfo propertyInfo = resolvedEntity.GetType().GetProperty(realPropertyName);
propertyInfo.SetValue(resolvedEntity,Convert.ChangeType(item.Value.StringValue,propertyInfo.PropertyType),null);
}
resolvedEntity.ReadEntity(props,null);
return resolvedEntity;
};
TableOperation retrieveOperation = TableOperation.Retrieve(partitionKey,rowKey,myEntityResolver);
TableResult retrievedResult = table.Execute(retrieveOperation);
var myRetrievedEntity = retrievedResult.Result as MyEntity;
// myRetrievedEntity.Dump();
#endregion
