c# - Dynamic Order By in Linq -


i have app accesses database , has order results different fields depending on input.

here function sorting:

iqueryable<entity> getsorteddata(iqueryable<entity> result, string orderby, bool desc) {    switch (orderby.tolower())    {      case "id":        result = result.orderby(c => c.id);        break;       case "code":        result = result.orderby(c => c.code);        break;       case "active":        result = result.orderby(c => c.active);        break;       default:        result = result.orderby(c => c.name);        break;    }     if (pagedata.sortdesc)    {      var res = result.tolist();      res.reverse();      return res.asqueryable();    }     return result;       }

there problems code don't like:

  1. too repetitive code. if "pure sql" query, like

    select * data_table order case @orderby when 'id' id when 'code' code
    when 'active' active else name
    end ;

  2. conversion list , reversing. can not change return type , not want write more useless code (essentially doubling switch case orderbydescending).

can suggest ways of making function better-looking, preferably still using linq?

well, definitely want use orderbydescending instead of reversing. it's not going quite brief sql, @ least use:

iqueryable<entity> getsorteddata(iqueryable<entity> result, string orderby, bool desc) {    switch (orderby.tolowerinvariant())    {      case "id":          return desc ? result.orderbydescending(c => c.id) : result.orderby(c => c.id);      case "code":          return desc ? result.orderbydescending(c => c.code) : result.orderby(c => c.code);      case "active":          return desc ? result.orderbydescending(c => c.active) : result.orderby(c => c.active);      default:          return desc ? result.orderbydescending(c => c.name) : result.orderby(c => c.name);    } }

you remove repetition own extension method:

public static iorderedqueryable<tsource> orderby<tsource, tkey>(     iqueryable<tsource> source,     expression<func<tsource, tkey>> keyselector,     bool descending) =>     descending ? source.orderbydescending(keyselector) : source.orderby(keyselector);

then write:

iqueryable<entity> getsorteddata(iqueryable<entity> result, string orderby, bool desc) {    switch (orderby.tolowerinvariant())    {      case "id": return result.orderby(c => c.id, desc);      case "code": return result.orderby(c => c.code, desc);      case "active": return result.orderby(c => c.active, desc);      default: return result.orderby(c => c.name, desc);    } }

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