Cannot implicitly convert type System Linq IQueryable to System Collections Generic IList

Question

I have a method   public DzieckoAndOpiekunCollection GetChildAndOpiekunByFirstnameLastname string firstname  string lastname        DataTransfer ChargeInSchoolEntities db   new DataTransfer ChargeInSchoolEntities        DzieckoAndOpiekunCollection result   new DzieckoAndOpiekunCollection        if  firstname    null  amp  amp  lastname    null                IList lt DzieckoAndOpiekun gt  resultV   from p in db Dziecko                       where lastname    p Nazwisko                         select   new DzieckoAndOpiekun                       p Imie                       p Nazwisko                       p Opiekun Imie                       p Opiekun Nazwisko                              result AddRange resultV             return result      and error in selected place       Error 1   Cannot implicitly convert type  System Linq IQueryable lt WcfService1 DzieckoAndOpiekun gt   to  System Collections Generic IList lt WcfService1 DzieckoAndOpiekun gt    An explicit conversion exists  are you missing a cast     Any idea how solve my problem

User · Accepted Answer

To convert IQuerable or IEnumerable to a list  you can do one of the following   IQueryable lt object gt  q        List lt object gt  l   q ToList      or   IQueryable lt object gt  q        List lt object gt  l   new List lt object gt  q

User · Answer

You can use the  ToList   method to convert the IQueryable result returned to an IList  as shown below  after the linq query      public DzieckoAndOpiekunCollection GetChildAndOpiekunByFirstnameLastname string firstname  string lastname        DataTransfer ChargeInSchoolEntities db   new DataTransfer ChargeInSchoolEntities        DzieckoAndOpiekunCollection result   new DzieckoAndOpiekunCollection        if  firstname    null  amp  amp  lastname    null                IList lt DzieckoAndOpiekun gt  resultV   from p in db Dziecko                       where lastname    p Nazwisko                         select   new DzieckoAndOpiekun                       p Imie                       p Nazwisko                       p Opiekun Imie                       p Opiekun Nazwisko  ToList                               result AddRange resultV             return result

User · Answer

Try this --    new DzieckoAndOpiekun                           p Imie                           p Nazwisko                           p Opiekun Imie                           p Opiekun Nazwisko  ToList

User · Answer

I ve got solved my problem this way in EF on list of records from db  ListOfObjectToBeOrder OrderBy x   gt  x columnName  ToList

User · Answer

You can replace IList lt DzieckoAndOpiekun gt  resultV with var resultV

User · Answer

If using a where clause be sure to include  First   if you do not want a IQueryable object

User · Answer

SonarQube reported Return an empty collection instead of null  and I had a problem with the error with casting as in the title of this question  I was able to get rid of both only using return XYZ ToList   AsQueryable    in a method with IQueryable like so  public IQueryable lt SomeType gt  MethodName           IQueryable lt SomeType gt  XYZ          return XYZ ToList   AsQueryable       Hope so it helps for those in a similar scenario s

[c#] Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.IList'

Examples related to c#

Examples related to .net

Examples related to linq

Examples related to exception-handling

Examples related to linq-to-entities