Only parameterless constructors and initializers are supported in LINQ to Entities

user_259227 0
Viewed 109494

I have this error in this linq expression :

var naleznosci = (from nalTmp in db.Naleznosci
                              where nalTmp.idDziecko == idDziec
                              select new Payments
                              (
                                  nalTmp.Dziecko.Imie,
                                  nalTmp.Dziecko.Nazwisko,
                                  nalTmp.Miesiace.Nazwa,
                                  nalTmp.Kwota,
                                  nalTmp.RodzajeOplat.NazwaRodzajuOplaty,
                                  nalTmp.RodzajeOplat.TypyOplat.NazwaTypuOplaty,
                                  nalTmp.DataRozliczenia,
                                  nalTmp.TerminPlatnosci
                              )).ToList();

Any idea how solve this problem? I try with any combination of expression... :/

linq-to-entities c#
14 Answers

Just use ToList() before the Select statement.. something like that:

myDbSet.Where(x => something that minimizes the number of items).ToList().Select(...)

The actual DbSet is not out of the db yet. After calling ToList() you're playing with objects, and then you can use a non-default constructor in the query.

Not the most efficient way usage-time wise, but it's an option on small sets.

user_10637760

Although it is late to answer, it could still help someone in distress. Since LINQ to entities do not support the parameter-less object constructions. However, the projection methods for IEnumerable.

So prior to selection, just convert your IQueryable to IEnumerable by using this code:

var result = myContext.SomeModelClass.AsEnumerable().Select(m => m.ToString());

It will work fine. However, it will, of course, loose the benefits of native queries.

user_104634210 
IQueryable<SqlResult> naleznosci = (from nalTmp in db.Naleznosci
                              where nalTmp.idDziecko == idDziec
                              select new Payments
                              {
                                  Imie = nalTmp.Dziecko.Imie,
                                  Nazwisko = nalTmp.Dziecko.Nazwisko,
                                  Nazwa= nalTmp.Miesiace.Nazwa,
                                  Kwota = nalTmp.Kwota,
                                  NazwaRodzajuOplaty =                          nalTmp.RodzajeOplat.NazwaRodzajuOplaty,
                              NazwaTypuOplaty = nalTmp.RodzajeOplat.TypyOplat.NazwaTypuOplaty,
                              DataRozliczenia = nalTmp.DataRozliczenia,
                              TerminPlatnosci = nalTmp.TerminPlatnosci,
                          });
Repeater1.DataSource  = naleznosci.ToList(); 
Repeater1.DataBind();


public class SqlResult
{
        public string Imie { get; set; }
        public string Nazwisko { get; set; }
        ...
}
user_135511870
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