C# 分别显示每个用户ID的开始和结束时间

我在每个

UserId

上运行

foreach

循环，但出于某种原因。。。在我的

xml

中，仅显示一个

用户ID

，以及所有

用户ID的所有开始时间和结束时间。我需要它分别显示每个
userId
的
start
和
end
时间

看起来是这样的：

User2
Start
End
Start
End
Start
End

User1
Start
End
Start
End

User2
Start
End

UserId    Time        EventType
Test1   xx-xx-xxxx   Start
Test1   xx-xx-xxxx   End
Test2   xx-xx-xxxx   Start

它需要如下所示：

User2
Start
End
Start
End
Start
End

User1
Start
End
Start
End

User2
Start
End

UserId    Time        EventType
Test1   xx-xx-xxxx   Start
Test1   xx-xx-xxxx   End
Test2   xx-xx-xxxx   Start

我的代码：

foreach (String userId in request.Users) // request.Users is a Array of UserId's 
{
    List<UserModel> result = // I am making my DataAccess Layer call here.
    UserRecord record = new UserRecord();
    record.UserId = userId;
    record.TimePeriodList = new List<TimePeriod>();
    for (int i = 0; i < result.Count; i += 2)
    {
        TimePeriod timeData = new TimePeriod();
        timeData.StartTime = result[i].TimeDate;
        // if result count is an odd number and this is the last iteration for the UserId
        if (((result.Count & 1) == 1) && (i == result.Count))
            {
                timeData.EndTime = result[i + 1].TimeDate;
            }
            record.TimePeriodList.Add(timeData);
        }
        response.UserRecordList = new List<UserRecord>();
        response.UserRecordList.Add(record);
}

public class GetUserResponse
{
    private List<UserRecord> userRecordList;

    public List<UserRecord> UserRecordList
    {
        get { return userRecordList; }
        set { userRecordList = value; }
    }
}

public class UserRecord
{
    private string userId;
    private List<TimePeriod> timePeriodList;

    public string UserId
    {
        get { return userId; }
        set { userId = value; }
    }

    public List<TimePeriod> TimePeriodList
    {
        get { return timePeriodList; }
        set { timePeriodList = value; }
    }
}

public class TimePeriod
{
    private DateTime startTime;
    private DateTime endTime;

    public DateTime StartTime
    {
        get { return startTime; }
        set { startTime = value; }
    }

    public DateTime EndTime
    {
        get { return endTime; }
        set { endTime = value; }
    }
}

因此，如果有一个奇数，那么该
用户的结束时间默认为
DateTime.MinValue
。
如果您单步执行程序，注意变量的状态，您可以很容易地发现错误。您的代码几乎可以正常工作，因为您可以返回结果。您看到的唯一结果是最后一个用户

让我们看看您的循环：

// you have created a response object here which I had to infer
var response = new GetUserResponse();  // added so my explanation makes sense

foreach (String userId in request.Users) // request.Users is a Array of UserId's 
{
    List<UserModel> result = // I am making my DataAccess Layer call here.
    UserRecord record = new UserRecord();
    // removed stuff that already works
    response.UserRecordList = new List<UserRecord>();
    response.UserRecordList.Add(record);
}

如果我们单步执行，直到行
response.UserRecordList=newlist（）这是状态：

response = instance1 of GetUserResponse
response.UserRecordList = null;
userId = test1

response = instance1 of GetUserResponse
response.UserRecordList = null;
userId = test1
record = instance1 of UserRecord with values in its fields

当我们跨过下一行时，状态变为

response.UserRecordList = new instance of List<UserRecord>(); // list1

现在，我们从数组中获取下一项，以便
userId
成为test2。
让我们再次运行到上一行，直到现在UserRecordList仍然有1个UserRecord，但是如果我们跨过这一行，就会创建一个新的实例，我将其称为列表2：

response.UserRecordList = new instance of List<UserRecord>(); // list2

response.UserRecordList=列表（）的新实例；//清单2

通过这一步，前面的列表1不再被引用，稍后将被垃圾收集。在最后一行中，添加了test2的UserRecord，然后我们就完成了

显然，创建userrecord列表的行不应该在foreach循环中

修复相当容易

var response = new GetUserResponse();  // added so my explanation makes sense
response.UserRecordList = new List<UserRecord>(); // init List once

foreach (String userId in request.Users) // request.Users is a Array of UserId's 
{
    List<UserModel> result = // I am making my DataAccess Layer call here.
    UserRecord record = new UserRecord();
    // removed stuff that already works
    // don't init the UserRecordList here, it is done at the start of the loop.
    response.UserRecordList.Add(record);
}

var response=new GetUserResponse（）；//所以我的解释是有意义的
response.UserRecordList=新列表（）；//初始化列表一次
foreach（request.Users中的字符串userId）//request.Users是userId的数组
{
List result=//我正在这里进行数据访问层调用。
UserRecord=新的UserRecord（）；
//删除了已经有效的东西
//不要在这里初始化UserRecordList，它是在循环开始时完成的。
response.UserRecordList.Add（记录）；
}
如果您单步执行程序，注意变量的状态，就可以很容易地发现错误。您的代码几乎可以正常工作，因为您可以返回结果。您看到的唯一结果是最后一个用户

让我们看看您的循环：

// you have created a response object here which I had to infer
var response = new GetUserResponse();  // added so my explanation makes sense

foreach (String userId in request.Users) // request.Users is a Array of UserId's 
{
    List<UserModel> result = // I am making my DataAccess Layer call here.
    UserRecord record = new UserRecord();
    // removed stuff that already works
    response.UserRecordList = new List<UserRecord>();
    response.UserRecordList.Add(record);
}

如果我们单步执行，直到行
response.UserRecordList=newlist（）这是状态：

response = instance1 of GetUserResponse
response.UserRecordList = null;
userId = test1

response = instance1 of GetUserResponse
response.UserRecordList = null;
userId = test1
record = instance1 of UserRecord with values in its fields

当我们跨过下一行时，状态变为

response.UserRecordList = new instance of List<UserRecord>(); // list1

现在，我们从数组中获取下一项，以便
userId
成为test2。
让我们再次运行到上一行，直到现在UserRecordList仍然有1个UserRecord，但是如果我们跨过这一行，就会创建一个新的实例，我将其称为列表2：

response.UserRecordList = new instance of List<UserRecord>(); // list2

response.UserRecordList=列表（）的新实例；//清单2

通过这一步，前面的列表1不再被引用，稍后将被垃圾收集。在最后一行中，添加了test2的UserRecord，然后我们就完成了

显然，创建userrecord列表的行不应该在foreach循环中

修复相当容易

var response = new GetUserResponse();  // added so my explanation makes sense
response.UserRecordList = new List<UserRecord>(); // init List once

foreach (String userId in request.Users) // request.Users is a Array of UserId's 
{
    List<UserModel> result = // I am making my DataAccess Layer call here.
    UserRecord record = new UserRecord();
    // removed stuff that already works
    // don't init the UserRecordList here, it is done at the start of the loop.
    response.UserRecordList.Add(record);
}

var response=new GetUserResponse（）；//所以我的解释是有意义的
response.UserRecordList=新列表（）；//初始化列表一次
foreach（request.Users中的字符串userId）//request.Users是userId的数组
{
List result=//我正在这里进行数据访问层调用。
UserRecord=新的UserRecord（）；
//删除了已经有效的东西
//不要在这里初始化UserRecordList，它是在循环开始时完成的。
response.UserRecordList.Add（记录）；
}