c# - Getting InvalidCastException when trying to implement sorting in Entity Framework Code First using Linq -

i have method below filterquery sorts data based on sortpropertyname property.

 private iqueryable<tentity> filterquery(expression<func<tentity, bool>> predicate, string sortpropertyname, orderby orderby = orderby.ascending)     {         iqueryable<tentity> entities = _dbentityset;         entities = (predicate != null) ? entities.where(predicate) : entities;         if (string.isnullorempty(sortpropertyname))         {             sortpropertyname = "id";         }         var keyselector = createselectorexpression<tentity>(sortpropertyname);         entities = (orderby == orderby.ascending) ? entities.orderby(keyselector) : entities.orderbydescending(keyselector);         return entities;     } 

aforementioned method in turn calls method createselectorexpression .

 private static expression<func<tentity, string>> createselectorexpression<tentity>(string propertyname)     {         try         {             var paramterexpression = expression.parameter(typeof(tentity));             return (expression<func<tentity, string>>)expression.lambda(expression.propertyorfield(paramterexpression, propertyname),                                                                     paramterexpression);         }         catch (exception ex)         {             string msg = ex.tostring();             return null;         }     } 

the above solution works fine when property of type string throw exception in case if property type numeric or date time. time being can see have hard-coded id property raise exception. here exception createselectorexpression throws when returning expression:

unable cast object of type 'system.linq.expressions.expression1[system.func2[myproject.business.domain.myclass,system.int32]]' type 'system.linq.expressions.expression1[system.func2[myproject.business.domain.myclass,system.string]]

can please me going on wrong in code or better soltion? please let me know if required more information me.

instead of building , expression scratch, can take expression on tentity key selector in place of sortpropertyname parameter :

private iqueryable<tentity> filterquery<tvalue>(expression<func<tentity, bool>> predicate, expression<func<tentity, tvalue>> sortexpression, orderby orderby = orderby.ascending)     {     iqueryable<tentity> entities = _dbentityset;              entities = (predicate != null) ? entities.where(predicate) : entities;     entities = (orderby == orderby.ascending) ? entities.orderby(sortexpression) : entities.orderbydescending(sortexpression);     return entities; } 

you can remove createselectorexpression function.

example of use :

filterquery<test>(p => p.id > 50, p => p.id, orderby.ascending) 

will filter result item having id greater 50 , sort them id property.