在需要说== NOT NULL的三元组中返回“NOT NULL”？

Question

鉴于这种代码：

  dataSource = this.db.DailyProductionReportSummaries.Where(
       x => x.ShiftDate >= start && x.ShiftDate <= end && 
       x.Shift == (shift != null ? shift.Code : "SOMETHING ELSE") && //TODO: "SOMETHING ELSE" where it's not null 
       x.LineNumber == (shift != null ? lineNumber : 0) && //TODO: 0 where it's not null 
       x.ProductCode == (productNumber != 0 ? productNumber.ToString() : "SOMETHING ELSE") //TODO: "SOMETHING ELSE" where it's not null 
       ).ToList(); 

我需要在每个标有“TODO”类似（针对专门与//TODO第一线的ternaries地说：

如果shift有东西在里面，返回shift.Code否则，返回将评估为x.Shift == NOT NULL（或更清楚地，它评估为x.shift != null）的“东西”

我在这里只是抱着一个愿望，还是我需要继续前进，并将其扩大为一堆if陈述？ （我试图凝聚多个if语句为没有大量的逻辑改变或重写的东西更紧凑，以适应不断变化的配置...

Answer 1

最可读的替代是机制扩展到了一堆if声明。请记住，你并不需要拼出每个备选方案，你不需要一堆if嵌套的，你可以通过调用Where反复根本链的过滤器。

var query = this.db.DailyProductionReportSummaries.AsQueryable(); 

query = query.Where(x => x.ShiftDate >= start && x.ShiftDate <= end); 

if (shift == null) 
    query = query.Where(x => x.Shift != null 
          && x.LineNumber != null); 
else 
    query = query.Where(x => x.Shift == shift.Code 
          && x.LineNumber == lineNumber); 

if (productNumber == 0) 
    query = query.Where(x => x.ProductCode != null); 
else 
    query = query.Where(x => x.ProductCode == productNumber.ToString()); 

dataSource = query.ToList();