c# - 使用 Linq 展平设备和仪表数据

Question

我正在使用一个树形控件，它要求我在将数据交给控件之前展平数据。我已经尝试了各种在线示例，但无法完全正确地“展平”数据。

• 设备有很多米
• 结果列表必须是 DeviceHierarchyDataItem 的(扁平化)列表

代码看起来像:
我猜我在这里走错了路......

public IQueryable<DeviceHierarchyDataItem> Query(int circuitConnectId)
{
    var devices = (from device in UnitOfWork.Device
                   join deviceCircuit in UnitOfWork.DeviceCircuit on device.Id equals deviceCircuit.DeviceId
                   where
                        deviceCircuit.CircuitConnectId == circuitConnectId
                   select device)
                   .Include( x=> x.Meters);

    // Not sure what to do NEXT (previous attempts have failed)
}

类(class):

public class DeviceHierarchyDataItem
{
    public int Id { get; set; } //<-- the 'Id' of the Device or Meter

    public int? ChildOf { get; set; }  //<-- the 'Id' of the PARENT Device or NULL

    public int CircuitConnectId { get; set; }

    public string DisplayName { get; set; } //<-- the 'Name' of the Device or Meter
}

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

    public string DeviceName { get; set; }

    public List<Meter> Meters { get; set; }
}

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

    public string MeterName { get; set; }
}

Answer 1

您可以使用 SelectMany展平集合的集合。

var devices = (from device in UnitOfWork.Device
               join deviceCircuit in UnitOfWork.DeviceCircuit on device.Id equals deviceCircuit.DeviceId
               where
                    deviceCircuit.CircuitConnectId == circuitConnectId
               select device)
               .Include( x=> x.Meters);

var deviceHierarchyDataItems = devices
    .SelectMany(device => device.Meters.Select(meter => new DeviceHierarchyDataItem
    {
        Id = meter.Id,
        ChildOf = device.Id,
        CircuitConnectId = 0, // don't know what you need here
        DisplayName = meter.MeterName
    }))
    .Concat(devices.Select(device => new DeviceHierarchyDataItem
    {
        Id = device.Id,
        ChildOf = null,
        CircuitConnectId = 0, // don't know what you need here
        DisplayName = device.DeviceName
    }));

或者:

var deviceHierarchyDataItems = devices
    .SelectMany(device => device.Meters.Select(meter => new DeviceHierarchyDataItem
    {
        Id = meter.Id,
        ChildOf = device.Id,
        CircuitConnectId = 0, // don't know what you need here
        DisplayName = meter.MeterName
    }).Concat(new List<DeviceHierarchyDataItem>()
    {
        new DeviceHierarchyDataItem
        {
            Id = device.Id,
            ChildOf = null,
            CircuitConnectId = 0, // don't know what you need here
            DisplayName = device.DeviceName
        }
    }));