此方法返回通用列表,但它有多个条件来获取选择。
我只是用 if - else if -else if... 来写这个,我的意思是这么多 if else
有没有更短的方法来做到这一点?谢谢。
public List<ProductReqNoDate> GetRequestsQuery(string departmant, int reqStateID, string firstDate, string lastDate)
{
var db = new requestsDBEntities();
var listPrn = new List<ProductReqNoDate>();
if (!string.IsNullOrEmpty(departmant))
{
return (from r in db.requests
where r.departmant== departmant
select new ProductReqNoDate
{
departmant= r.departmant,
reqNo = r.reqNo ,
reqDate = r.reqDate ,
prdctName= stringCutter((from p in db.products where p.reqNo == r.reqNo select p.prdctName).FirstOrDefault())
}).ToList();
}
if (!string.IsNullOrEmpty(firstDate) && !string.IsNullOrEmpty(lastDate))
{
DateTime dtfirstDate = Convert.ToDateTime(firstDate);
DateTime dtlastDate = Convert.ToDateTime(lastDate);
return (from r in db.requests
where r.reqDate <= dtlastDate && r.reqDate >= dtfirstDate
select new ProductReqNoDate
{
departmant= r.departmant,
reqNo = r.reqNo ,
reqDate = r.reqDate,
prdctName= stringCutter((from p in db.products where p.reqNo == r.reqNo select p.prdctName).FirstOrDefault())
}).ToList();
}
}
您可以将查询的核心设置如下:
var query = from r in db.requests
select new ProductReqNoDate
{
departmant= r.departmant,
reqNo = r.reqNo ,
reqDate = r.reqDate ,
prdctName= stringCutter((from p in db.products
where p.reqNo == r.reqNo select p.prdctName).FirstOrDefault())
}
然后申请if then else
:
if (!string.IsNullOrEmpty(departmant))
return query.Where(r=>r.departmant== departmant).ToList();
if (!string.IsNullOrEmpty(firstDate) && !string.IsNullOrEmpty(lastDate))
{
DateTime dtfirstDate = Convert.ToDateTime(firstDate);
DateTime dtlastDate = Convert.ToDateTime(lastDate);
return query.Where(r=> r.reqDate <= dtlastDate && r.reqDate >= dtfirstDate)
.ToList();
}
并没有减少if then else
但让发生的事情变得更明智。
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