Only parameterless constructors and initializers are supported in LINQ to Entities

Question

I have this error in this linq expression :

var naleznosci = (from nalTmp in db.Naleznosci
                              where nalTmp.idDziecko == idDziec
           


        

Answer 1

First I would avoid the solution with

from ....
select new Payments
{
  Imie = nalTmp.Dziecko.Imie,
  ....
}

This requires an empty constructor and ignores encapsulation so you are saying new Payments() is a valid payment without any data, but instead the object must have at least a value and probably other required fields depending on your domain.

It's better to have a constructor for required fields but only bring needed data:

from ....
select new
{
  Imie = nalTmp.Dziecko.Imie,
  Nazwisko = nalTmp.Dziecko.Nazwisko
  ....
}
.ToList() // Here comes transfer to LINQ to Collections.
.Select(nalImp => new Payments
 (
  nalTmp.Imie,//assume this is a required field
  ...........
  )
  {
     Nazwisko = nalTmp.Nazwisko //optional field
  })
.ToList();