Question

我尝试了以下内容。目前，我只是想读取控制台中查询的对象集合。根据该指南，首选异步查询：http://docs.parseplatform.org/dotnet/guide/#queries

public class IndexModel : PageModel
    {
        public void OnGet()
        {
            Task<int> task = HandleMessagesAsync();
            task.Start();

        }

        private async Task<int> HandleMessagesAsync()
        {
            var query = ParseObject.GetQuery("Message");
            IEnumerable<ParseObject> results = await query.FindAsync();

            Console.WriteLine(results);

            throw new NotImplementedException();
        }
    }

我收到以下错误：

System.InvalidOperationException: 'Start may not be called on a promise-style task.'

Answer 1

Task课程会根据本指南自动启动：https://social.msdn.microsoft.com/Forums/vstudio/en-US/70f82b79-188e-4e91-8f86-b5a9382663fb/problem-with-taskstart?forum=netfxbcl

无需调用.Start();

public class IndexModel : PageModel
    {
        public void OnGet()
        {
            Task<int> task = HandleMessagesAsync();
        }

        private async Task<int> HandleMessagesAsync()
        {
            var query = ParseObject.GetQuery("Message");
            IEnumerable<ParseObject> results = await query.FindAsync();
            var count = await query.CountAsync();

            Debug.WriteLine("# Message: " + count);

            throw new NotImplementedException();
        }
    }

我使用Debug.WriteLine("# Message: " + count);来确保从我的数据库中查询正确数量的Message对象。

如何在ASP.NET MVC应用程序中异步查询ParseObject集合？

1 个答案: