Azure october 2012 sdk - 如何删除表实体而不先检索它？

Question

在以前的版本中,我们可以在不知道它是否存在的情况下删除实体.

svc = new TestContext();
item = new TestEntity("item2pk", "item2rk");
svc.AttachTo("TestTable", item, "*");
svc.DeleteObject(item);
svc.SaveChanges();

(资源)

新的TableOperations没有此语法.我必须使用这种旧方法还是有办法？我想保持一致,因为现在我的所有代码都使用了第2版的新类.

编辑:标题具有误导性

Answer 1

你需要使用TableOperation.Delete:

var storageAccount = CloudStorageAccount.DevelopmentStorageAccount;
var table = storageAccount.CreateCloudTableClient()
                            .GetTableReference("tempTable");
table.CreateIfNotExists();

// Add item.
table.Execute(TableOperation.Insert(new TableEntity("MyItems", "123")));

// Load items.
var items = table.ExecuteQuery(new TableQuery<TableEntity>());
foreach (var item in items)
{
    Console.WriteLine(item.PartitionKey + " - " + item.RowKey);
}

// Delete item (the ETAG is required here!).
table.Execute(TableOperation.Delete(new TableEntity("MyItems", "123") { ETag = "*" }));

删除仅适用于存在的实体.即使旧客户端有ContinueOnError选项,它也与Batch操作不兼容(如此处所述).

成功批量删除的唯一方法是,如果您不知道实体存在它,则首先添加它们(或者如果它们已经存在则替换它们):

var ensureItemsBatch = new TableBatchOperation();
ensureItemsBatch.InsertOrReplace(new MyEntity("MyItems", "123") { Active = false });
ensureItemsBatch.InsertOrReplace(new MyEntity("MyItems", "456") { Active = false });
ensureItemsBatch.InsertOrReplace(new MyEntity("MyItems", "789") { Active = false });
table.ExecuteBatch(ensureItemsBatch);

var deleteItemsBatch = new TableBatchOperation();
deleteItemsBatch.Delete(new MyEntity("MyItems", "123") { ETag = "*" });
deleteItemsBatch.Delete(new MyEntity("MyItems", "456") { ETag = "*" });
deleteItemsBatch.Delete(new MyEntity("MyItems", "789") { ETag = "*" });
table.ExecuteBatch(deleteItemsBatch);

Answer 2

我使用自己的方法来捕获当实体不存在时发生的StorageException.此外,它返回实体是否被删除为bool.

public bool DeleteTableEntity(string partitionKey, string rowKey)
{
    try
    {
        _table.Execute(TableOperation.Delete(new TableEntity(partitionKey, rowKey) { ETag = "*" }));
        return true;
    }
    catch (StorageException e)
    {
        if (e.RequestInformation.HttpStatusCode == (int)HttpStatusCode.NotFound)
            return false;
        throw;
    }
}

_table成员变量的类型为CloudTable(Microsoft.WindowsAzure.Storage.Table.CloudTable).对于此示例,我使用与NuGet一起安装的程序集Microsoft.WindowsAzure.Storage.dll,v2.1.0.3.