Property for contacting fields in query LINQ to Entities

Question

I have in Database table Users:

pk firstName lastName
1  Mary      Snow
...

LINQ to Entities create class:

public partial class User
{
   public int pk { get; set; }
   public string firstName { get; set; }
   public string lastName { get; set; }
}

I tried to create new part of this class

public partial class User
{
   public string FullName 
   {
      get
      {
        return lastName + " " + firstName;
      }
   }
}

And after i tried to use it in IQueryable i get exception "The specified type member 'FullName' is not supported in LINQ to Entities". Can i create property or extension method for this?

I need it in many parts of my code. And it is not comfortable for me use in every query lastName + " " + firstName. I don't understand why i can use in IQueryable "where(x=> (x.lastName + " " + x.firstName) == "Mary Show")" but i can't write new property and use it as "where(x=> x.FullName == "Mary Show")".

It is example in really i have more modifications of fields.

upd: I use .NET Framework 4.5.2 and Entity Framework 6.

upd2: I use Database-First approach.

I tried it. I added using System.ComponentModel.DataAnnotations.Schema; And After it i add [NotMapped] attribute. It not helped, i get exception when use it. — Константин Золин, Mar 06 '20 at 03:18
No. Thank you for comment, I add information about it in question. — Константин Золин, Mar 06 '20 at 03:22
Do you mind elaborating a bit on how you are using the property. Note, I thought you are just reading in the entity. You cannot access properties like fullName in IQueryable — Heinrich, Mar 06 '20 at 03:24
If you are doing something nasty like searching on FullName you have to trick Entity Framework. ie. table.Where(x=>DbFunctions.Like(x.firstName+ " "+x.lastname,"bob"); — Heinrich, Mar 06 '20 at 03:31
Now I not use this property, I try to create it and improve my code. Now I use it in where cases, order cases and selects. I use ad (x.lastname + " " + x.firstName) == smth. Or i use orderby(x=> x.lastname + " " + x.firstName).Skip(5).Take(15).ToList() — Константин Золин, Mar 06 '20 at 03:31
orderby(x=> x.lastname + " " + x.firstName).Skip(5).Take(15).ToList() can change to orderby firstName and also last name. — Harris Yer, Mar 06 '20 at 03:45
I partially solved this problem using extensions as in this question: https://stackoverflow.com/questions/48192827/entity-framework-linq-use-expressions-in-select/49034913#49034913 It isn't property but it helps to use one logic for selecting. — Константин Золин, Oct 12 '21 at 03:15

score 0 · Answer 1 · answered Mar 06 '20 at 03:27

0

You can alternatively do this with Fluent API overriding OnModelCreating function in your DBContext class:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
   modelBuilder.Entity<User>().Ignore(t => t.FullName );
   base.OnModelCreating(modelBuilder);
}

answered Mar 06 '20 at 03:27

akurasu

13
4

Oh, sorry. I use Database-First approach, i forgot to write about it. – Константин Золин Mar 06 '20 at 04:55

Property for contacting fields in query LINQ to Entities

1 Answers1