如何使用 Azure TableClient 2.0 BeginExecuteQuerySegmented

问题描述

我正在尝试异步获取表中的所有条目，但无法弄清楚如何使用 延续令牌.我怀疑我需要采用我的匿名方法并将其转换为委托，然后使用延续令牌递归调用它.

I'm trying to get all entries in my table asynchronously but am unable to figure out how to work with the continuation token. I suspect I need to take my anonymous method and convert it to a delegate, then recursively call it with the continuation token.

如何使用以下代码并执行异步调用并获取新 API 中的所有条目?

How do I take the following code and perform an Async call and fetch all entries in the new API?

 Task<string[]> GetAllTableEntries(CloudTable tbl, string[] urls, string name, CancellationToken token)
    {
        TableRequestOptions reqOptions = new TableRequestOptions() { };
        OperationContext ctx = new OperationContext() { ClientRequestID = "" };
        object state = null;

        // Register Cancelation Token
        ICancellableAsyncResult result = null;

        TableQuery qry = new TableQuery();
        TableContinuationToken tok = null;

        result = tbl.BeginExecuteQuerySegmented(qry, tok, reqOptions, ctx, (o) =>
        {

            var response = (o.AsyncState as CloudTable).EndExecuteQuerySegmented(o);

            Console.WriteLine("Found " + response.Results.Count + " records");

            // The following code was used in the previous version of the SDK
            //
            //26:                      // add first segment of data
            //27:                      pageData.CompletedList.AddRange(
            //28:                          from wu in response.Results
            //29:                          select new CompletedWorkUnit(wu));
            //30:
            //31:                      // continue fetching segments to complete page
            //32:                      while (response.HasMoreResults)
            //33:                      {
            //34:                          response = response.GetNext();
            //35:                          pageData.CompletedList.AddRange(
            //36:                              from wu in response.Results
            //37:                              select new CompletedWorkUnit(wu));
            //38:                      }
            //39:
            //40:                      // set continuation token for next page request
            //41:                      pageData.ContinuationToken = response.ContinuationToken;
            //42:                      evt.Set();

        }, state);

        // Add cancellation token according to guidance from Table Client 2.0 Breaking Changes blog entry
        token.Register((o) => result.Cancel(), state);

推荐答案

请试试这个:

    static void ExecuteQuery()
    {
        TableContinuationToken token = null;
        TableRequestOptions reqOptions = new TableRequestOptions() { };
        OperationContext ctx = new OperationContext() { ClientRequestID = "" };
        long totalEntitiesRetrieved = 0;
        while (true)
        {
            CloudTable table = cloudTableClient.GetTableReference("MyTable");
            TableQuery<TempEntity> query = (new TableQuery<TempEntity>()).Take(100);
            System.Threading.ManualResetEvent evt = new System.Threading.ManualResetEvent(false);
            var result = table.BeginExecuteQuerySegmented<TempEntity>(query, token, reqOptions, ctx, (o) =>
            {
                var response = (o.AsyncState as CloudTable).EndExecuteQuerySegmented<TempEntity>(o);
                token = response.ContinuationToken;
                int recordsRetrieved = response.Count();
                totalEntitiesRetrieved += recordsRetrieved;
                Console.WriteLine("Records retrieved in this attempt = " + recordsRetrieved + " | Total records retrieved = " + totalEntitiesRetrieved);
                evt.Set();
            }, table);
            evt.WaitOne();
            if (token == null)
            {
                break;
            }
        }
    }

我注意到的一件事是，如果我执行返回动态表实体的查询，则会收到与 DateTimeOffset 相关的错误.这就是为什么我最终创建了一个临时实体.

One thing I noticed is that if I execute a query which returns a dynamic table entity, I'm getting an error related to DateTimeOffset. That's why I ended up creating a temporary entity.

希望这会有所帮助.

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