小编Ser*_*erl的帖子

我们希望使用Entity Framework Code First使用一对一的可选关系.我们有两个实体.

public class PIIUser
{
    public int Id { get; set; }

    public int? LoyaltyUserDetailId { get; set; }
    public LoyaltyUserDetail LoyaltyUserDetail { get; set; }
}

public class LoyaltyUserDetail
{
    public int Id { get; set; }
    public double? AvailablePoints { get; set; }

    public int PIIUserId { get; set; }
    public PIIUser PIIUser { get; set; }
}

PIIUser可能有LoyaltyUserDetail但LoyaltyUserDetail必须有PIIUser.我们尝试了这些流畅的方法技巧.

modelBuilder.Entity<PIIUser>()
            .HasOptional(t => t.LoyaltyUserDetail)
            .WithOptionalPrincipal(t => t.PIIUser)
            .WillCascadeOnDelete(true);

这种方法没有 …

我的代码发出https请求.这是我的代码

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(UploadUrl);
            request.Method = "POST";
            request.KeepAlive = false;
            request.Credentials = new NetworkCredential(userid, testpwd);

            postData = "<root></root>";
            request.ContentType = "application/x-www-form-urlencoded";

            byte[] postDataBytes = Encoding.UTF8.GetBytes(postData);
            request.ContentLength = postDataBytes.Length;

            Stream requestStream = request.GetRequestStream();
            requestStream.Write(postDataBytes, 0, postDataBytes.Length);
            requestStream.Close();

            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                StreamReader responseReader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                var result = responseReader.ReadToEnd();
                responseReader.Close();
                Console.WriteLine(result);
            }

这段代码运行良好但突然抛出异常

System.Net.WebException

Run Code Online (Sandbox Code Playgroud)

异常消息是:基础连接已关闭:发送时发生意外错误.

堆栈跟踪:位于System.Net.HttpWebRequest.GetRequestStream(TransportContext&context)的System.Net.HttpWebRequest.GetRequestStream(),位于CustomerProcessor.Delivery.Deliver(String content,Int32 productCategory,String identifier,String xsltFile)

Exception有一个内部异常:发生异常:System.IO.IOException异常消息是:从传输流中收到意外的EOF或0字节.

堆栈跟踪:System.Net上的System.Net.FixedSizeReader.ReadPacket(Byte []缓冲区,Int32偏移量,Int32计数)处于System.Net的System.Net.Security.SslState.StartReadFrame(Byte []缓冲区,Int32 readBytes,AsyncProtocolRequest asyncRequest).在System.Net.Security.SslState.StartSendBlob(Byte []传入,Int32计数,System.SNet.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken消息,AsyncProtocolRequest asyncRequest)上的Security.SslState.StartReceiveBlob(Byte []缓冲区,AsyncProtocolRequest asyncRequest),位于System.Net.TlsStream.CallProcessAuthentication(对象状态)的System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)的System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst,Byte [] buffer,AsyncProtocolRequest asyncRequest)中的AsyncProtocolRequest asyncRequest) …

                        new ListView(
                          children: [
                            new SizedBox(
                              height: 100.0,
                              child: ListView(
                                scrollDirection: Axis.horizontal,
                                children: <Widget>[
                                  new Text("hi"),
                                  new Text("hi"),
                                  new Text("hi"),
                                ],
                              ),
                            ),
                          ],
                        ),

我使用了大小的盒子,似乎仍然有错误.

这是我的小部件树:SingleChildScrollView - > Column - > children

Performing hot reload... flutter: ??? EXCEPTION CAUGHT BY RENDERING LIBRARY ?????????????????????????????????????????????????????????? flutter: The following assertion was thrown during performResize(): flutter: Vertical viewport was given unbounded height. flutter: Viewports expand in the scrolling direction to fill their container.In this case, a vertical flutter: viewport was given an unlimited …

我有这样一个模型的列表

amount:"12000"
dateTime:"19/07/2018"
detail:"Soto"
hashCode:853818549
id:1
name:"Theodorus"

我只想选择数量并将其添加到另一个字符串列表中，但我总是收到此错误A value of type 'String' can't be assigned to a variable of type 'List<String>'. ，我认为这是因为我没有做对，下面是我的代码

void setupList() async {
    DebtDatabase db = DebtDatabase();
    listCache = await db.getMyDebt();
    setState(() {
      filtered = listCache;
    });
     List<String> amount = new List<String>();
    listCache.map((value)  {
      amount = value.amount;   } );
    //print(amount);
  } 

任何人都可以帮助我，所以我可以从这个模型列表中获取数量列表，然后总结所有的数量？

我的 showDialog 有问题，当我按下没有任何反应但如果我使用Navigator.pushNamed(context, "/screen1")它就可以了。我无法运行Navigator.pop(context)，它不会返回任何错误。

_showDialog(BuildContext context) {
return showDialog(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: new Text("Alert Dialog title"),
        actions: <Widget>[
          new FlatButton(
            child: new Text("Back"),
            onPressed: () {
              //Navigator.pushNamed(context, "/screen1");
              Navigator.pop(context);
            },
          ),
        ],
      );
    });}

在我的 build() 中：

IconButton(
iconSize: 30.0,
onPressed: () => _showDialog(context),
icon: Icon(
  Icons.clear,
  color: Colors.white,
 ),

)

我正在使用 GraphQL 创建一个订阅，我需要使用 Flutter 使用该订阅，但我不知道如何做到这一点，我需要的东西就像一个与订阅相关联的 UI 组件，它会会自动刷新。

我将不胜感激任何反馈。

我遵循了将 EF Core 与 ASP.NET Core 一起使用的模式，一切都很好。但最近我创建了一个“计算”项目，并希望从中进行数据库调用。

问题是我不知道如何创建一个新的DbContextOptions. 在我完成的代码中

   services.AddDbContext<RetContext>(options => options
            .UseLazyLoadingProxies()
            .UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

但是在新的 .NET 核心类中，我需要手动提供它。我该怎么做呢 ？我的代码是这样的：

 public static class LoadData
{
    public static IConfiguration Configuration { get; }

    public static RefProgramProfileData Load_RefProgramProfileData(string code)
    {
        // var optionsBuilder = new DbContextOptionsBuilder<RetContext>();
        // optionsBuilder.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));

        //How do I make an optionsbuilder and get the configuration from the WEB project?
       UnitOfWork uow = new UnitOfWork(new RetContext(optionsBuilder));


        var loadedRefProgramProfileData  = uow.RefProgramProfileDataRepository
            .Find(x => x.ProgramCode == code).FirstOrDefault();

        return loadedRefProgramProfileData;
    }
}