LINQ - 动态排序依据条款无效 [英] LINQ - dynamic orderby clause does not work

问题描述

我有code是这样的：

I have code like this:

//build query
var shops = (from p in dataContext.shops
let distance = dataContext.GetDistance(p.lat, p.lon, nearlat,nearlon)
                     join c in dataContext.shops_category on p.id equals c.poi_id
                     select new ShopsModel { p = p, distance = distance }
                         );
        }
//add dynamic orderby
if(somthig) 
  shops.OrderBy(distance)
else 
  shops.OrderBy(p.name)


//get records.
return shop.Take(30).ToList()

它工作正常，只是排序依据。生成的SQL code不包含排序依据子句和记录进行排序。

It's works fine except OrderBy. Generated SQL code does not contains orderby clause and the records are not sorted.

你知道吗？感谢您的帮助。

Any Idea? Thanks for help.

推荐答案

排序依据并没有发生变异的基础数据 - 它返回一个枚举用适当的排序。您需要将结果返回分配给商店：

OrderBy does not mutate the underlying data - it returns an enumerable with the appropriate ordering. You need to assign the result back to shops:

if (someCondition) 
{
  shops = shops.OrderBy(shop => shop.distance);
}
else 
{
  shops = shops.OrderBy(shop => shop.p.name);
}

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