Question

foreach（在新DataAccess.IncidentRepository（）中的var事件.GetItems（）。其中（ i =＆gt; （startDate == null || i.IncidentDate＆gt; = startDate）＆安培;＆安培; （endDate == null || i.IncidentDate＆lt; = endDate）＆安培;＆安培; （shiftId == null || i.ShiftId == shiftId）＆安培;＆安培; （processAreaId == null || i.ProcessAreaId == processAreaId）＆安培;＆安培; （plantId == null || i.PlantId == plantId）））

如果i.PlantId == plantId为plantId，我可以null无法添加吗？

由于

Answer 1

var incident in new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId
                    && (plantId == null || i.PlantId == plantId)))

或者，您可以：

var incidents = new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId));

if (plantId != null)
    incidents = incidents.Where(i => i.PlantId == plantId);

foreach (var incident in incidents) {
   // ...
}

Answer 2

var incident in new DataAccess.IncidentRepository().GetItems().Where(
                    i => i.IncidentDate >= startDate 
                    && i.IncidentDate <= endDate 
                    && i.ShiftId == shiftId 
                    && i.ProcessAreaId == processAreaId
                    && object.Equals(i.PlantId, plantId)))

Linq2SQL检查item是否为null

2 个答案: